# V8 nitro engine



## Parksy (Jan 9, 2016)

Gday all

First time poster and relatively new machinist(6 months maybe). I've made a couple of steam engines, first was a single cylinder double acting steam engine from plans, the second is a 4cyl double acting engine that I just made without plans, and works very well, in fact I can power it with lung power alone.

Anyway, I'm making my first IC engine and have decided with a v8 four stroke nitro engine. It's progressing well and my inspiration came from an engine made by DickinOhio. I found this a fantastic looking engine and wanted something similar.
I've just finished making piston rings and running them in on the lathe, and they sure add a lot of resistance to the engine. Is this the norm? Without the rings installed, the crank spun nice and freely, even with Pistons installed.

I'm starting to work on the heads and will be making bronze valve cages with stainless valves. What is the preferred material for the rocker arms?

Thanks all for viewing and I'm sure I'll have a lot more questions later on.

Cheers

Andy


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## Parksy (Jan 9, 2016)

Having issues uploading multiple images, only allowing one per post for some reason.


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## Parksy (Jan 9, 2016)




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## gus (Jan 9, 2016)

Hi Parksy,

Your build is fantastic.


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## Parksy (Jan 9, 2016)

Thank you Gus.

Here are some shots I took earlier in the build.

























The cylinder liners I made out of steel. I was concerned with corrosion so I've electrically plated them with nickel, which is surprisingly easy to do at home with very basic ingredients.
When breaking the rings in, I was concerned that the nickel would cause issues, but it didn't and compression is excellent. If I cover the valve ports with my fingers while it's turning on the lathe, the oil inside sprays out as a fine mist. (Or sucks my fingers in, depending on the stroke).

Cheers


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## Parksy (Jan 9, 2016)

Soon I intend the drill the intake and exhaust ports through the heads. I was just wondering what a suitable size hole I should make? Engine bore and stroke are 22mm.


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## petertha (Jan 9, 2016)

Parksy said:


> ..
> I've just finished making piston rings and running them in on the lathe, and they sure add a lot of resistance to the engine. Is this the norm? Without the rings installed, the crank spun nice and freely, even with Pistons installed....What is the preferred material for the rocker arms?Andy


 
Very impressive build Andy. There are way smarter guys than me on the forum to chime in, but here goes with my 2 cents:

- re the piston & rings: the ringed nitro 4-stroke engines I've seen generally have piston diameter about .002" smaller than bore. So no 'resistance' from the piston only standpoint.

- re rings, a whole subject with varied views. But many successful builds have followed the Trimble method for sizing. Once you know the bore, basically the remaining ring parameters drop out of some simple formulas: ring cross section dimensions & what distance they are spread to 'heat set' & final gap (assuming cast iron as he recommends). The radial I'm building is quite close to an RC OS-56-4S & I validated the commercial ring seems very close to the Trimble parameters. Then the piston groove to accommodate the ring with appropriate clearances results from that.

- re rockers, I think the norm is to harden at least the face area that contacts valve stems if that's the configuration. Personally I'm going to try O1 tool steel. I've read others use plain steel & case harden with those powder dip products.

I'd like to learn more about your liner plating methods & materials. If you saved any pics & notes that would be awesome. Is the plan to post lap the plated surface? What sort of thickness do you figure it added? 

I'm looking at your engine & wondering about cooling. What's the plan there?


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## Parksy (Jan 10, 2016)

Gday Petertha and thanks for the response. With regards to cooling, the plan is to build it first and get it running, then monitor each cylinder to see what the temp wants to do. if it wants to get hot then I'll mount the heatsinks onto the rotary table and use a slitting saw to cut some cooling fins.

The nickel plating was straight forwards. Vinegar, a dc power supply and some nickel. I found the nickel the hardest part to source but found some on eBay. Put a chunk of nickel on each end of the positive and negative leads and dip it into the vinegar with power applied. Takes a few hours, but the nickel slowly dissolves into the vinegar and it turns green creating nickel acetate. Remove the nickel from the negative terminal and put your work piece onto it (after its been cleaned, free from oils etc). I left the liners in the solution for about 15mins and this produced a fairly thick layer that did create issues with reinstalling into the engine, but this was overcome with a little extra effort. I didn't measure the size before and after but it did change the size slightly. The liners were honed before plating, and i ran the rings onto the plated surface. Seemed to have worked and the plating is very durable. Mind you this is a very vague description so if you want more details I'm happy to help where possible. But at the end of the day it worked a treat and gave the me the rust protection I wanted.


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## kadora (Jan 10, 2016)

Hi Parksy
I have cylinders inner dia 22mm on some of my engines and i drill
6 mm portholes.
I am surprised to read your remedy for nickel coating.
It seems to be very easy but could you tell me please ---
when i have nickel acetate solution done then work piece is 
connected to the same voltage as during making acetate solution?
How high is amperage?
Here in Europe nickel plating solution is terribly expensive and your process
would dramatically decrease coating price.
Thank you a lot
Kadora


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## Parksy (Jan 10, 2016)

Hi kadora 

From what I've read, the recommendation is to use a couple of D sized batteries (1.5v each). I tried this and didn't have much success. That or I just needed to wait longer. I tried a 12v battery charger and this worked a treat. According to the meter, it pulled close to 4 amps and the solution did get warm. This could have been too much, but I had success with it. 
With regards to making the nickel acetate, if the solution turns a nice transparent green(like green cordial) then you've got a pure nickel source. If it's cloudy or a different colour, it's mixed with other metals.

I hope this helps.


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## kadora (Jan 10, 2016)

I am going to try this process right now is Sunday rainy morning here
ideal time for experiments .
I will inform you about results.


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## Parksy (Jan 10, 2016)

Good luck kadora.

I've attached two photos of the same object, what I've done is very quickly machined the outside diameter to remove what ever scale/rust and what not, and have left the inside untouched. I didn't clean it either, was just a test piece. But I've nickel plated it, and because I didn't touch the inside diameter, it didn't receive any plating. Too dirty or something.
Anyway, I left it out in the rain to expose it to the elements and I'm happy with how it's performed. The outside shows no rust, and the inside, well as you can see has performed as well as it does.


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## kadora (Jan 10, 2016)

Nickel coating works . 
Coating is not shiny but it is much much better than painting by zinc spray or so and it is excellent rust protection.
This week i will coat my already machined parts for new V twin.
On picture is partly coated piece of brass .
Thank you Parksy for your help.
One more question.
Do you have some picture of crankshaft machining for your V8?
I would like to see your way of crankshaft machining process.
Thank you


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## Parksy (Jan 10, 2016)

Glad it worked kadora. I believe the nickel can be polished to produce a shine.

Here's some more pics of the crank shaft. What I've done is machined the discs separately and fixed them to some rod which I turned down on the lathe to try and produce a straight crank. I've also mounted ball bearings for the main bearings onto the rod, and used bronze bushes as the big and small end bearings. The discs are loctited using max strength retaining compound then drilled and pinned to the shaft. Then milled the required bits off the rod to give me the final product.


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## Cogsy (Jan 10, 2016)

Parksy said:


> I believe the nickel can be polished to produce a shine.


 
No plating really gives a natural shine unless the surface it is going on to is already shiny. If you polish the surface before you plate then you'll be able to get a nice chromed look on your parts (although nickel plating has a slightly different sheen to chrome).


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## kadora (Jan 11, 2016)

Thanks Parksy
I machine crankshafts in the same way.


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## Parksy (Jan 11, 2016)

Started some head work today, drilled the exhaust ports, tapped them and made some stainless tips that I've threaded and simply screw into the head. 
I'm looking forwards to making the valves and cages and rockers. Should really set the engine off, I hope.


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## Parksy (Jan 12, 2016)

Valve cage and valve. Cage is bronze and valve is 316 stainless. Not the nicest to machine but I've managed. Haven't had much luck sourcing 303 stainless here in oz. if anyone knows, I'm all ears!


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## mnay (Jan 12, 2016)

Beautiful work.  Keep us posted.


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## Parksy (Jan 13, 2016)

More valve cages. Just need to clean them up and mill a hole so they can work. 
Had issues with making valves today. The stainless just wanted to flex too much, even if I used a live center on the end. Was ending up with uneven thicknesses across the stem. What methods does everyone else use for making valves? And what materials? I was using 316 stainless.




With regards to valve seat angles, I set the compound slide on the lathe to 40 degrees and cut the valve seat. Would I be correct in simply setting it to 40 degrees to cut the opposite angle for the actual valve? Or will this angle be 50 degrees? I apologise for what may be a very straight forward question. Been a very hot day here in oz.

Cheers


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## petertha (Jan 13, 2016)

Parksy said:


> Had issues with making valves today. The stainless just wanted to flex too much, even if I used a live center on the end. Was ending up with uneven thicknesses across the stem.
> 
> I set the compound slide on the lathe to 40 degrees and cut the valve seat. Would I be correct in simply setting it to 40 degrees to cut the opposite angle for the actual valve? Or will this angle be 50 degrees? I


 
re valve alloy, I ended up trying 416 based on machinability charts like this. I needed to buy material anyway so figured try & stack the deck in my favor. I also tried (I think) 303, didn't seem radically different at least for this part & my tooling/technique. Shades of crappy  I learned you cant creep up on it to skiff off the last thou because it can work harden (might be part of your issue in disguise?). Really sharp tools performed best.
https://www.google.ca/search?q=machinability+comparison+stainless&biw=1642&bih=999&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiA9vzxvqfKAhVMxGMKHQDZCb8QsAQIOQ#imgrc=SgqDPfJRlrWs0M%3A

Re finishing, I worked my ~ 0.004" roughish turned finish down with hard backed emory paper sticks & miked along the stem until it was in the sizing range for homebrew lap post #9. My tool worked quite well but of course the tailstock support chunk must be removed to slide the lap on.
http://www.homemodelenginemachinist.com/showthread.php?t=24516

I like the looks of this self made mini clamp hone. Its on my list of tools to make & try. My thought is make it say 50-75% the valve stem length so I can traverse & correct any diameter changes? http://philsradial.blogspot.ca/2012/02/valves.html

ps- I'm a rookie, just stumbling behind what I respectfully steal l from others. Check out Terry's radial build posts in particular. There are other good ones too, just that comes to mind immediately on valve stuff.

re seat angle, I think the common mode is to strive for cage/valve face equal angles but a proper & very thin contact line for seal. How this is achieved is documented in other builds,or others can chime in. FWIW I measured a commercial RC 4S engine at 0.015-0.020" chamfer on the valve cup as I recall.


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## Swifty (Jan 13, 2016)

When I have made valves, I machine the stem in steps of about 10mm length at a time. This helps prevent the stem from pushing away as you machine it, when final length has been reached the use of some fine emery backed up by a file evens out any blips.

Paul.


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## stevehuckss396 (Jan 13, 2016)

I make valves using O1 drill rod (silver steel). I also get taper in the stem but only 1 or 2 thousands. I then work them with sand paper until they are straight. I doesn't take but 5 minutes to straighten them out. Patience and frequent measuring and a little practice and you can get them within just a 1 or 2 tenths.


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## Johno1958 (Jan 13, 2016)

I think you can get 303 stainless from Bohler Uddeholm in Melbourne.
Cheers
John


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## Parksy (Jan 13, 2016)

Thank you all! This helps me a lot! Has anyone used a steady rest for these kinds of things? Do they only get used on the final pass? I don't properly know how to use them, because if the surface is uneven, then it will force the material into the cutting tip unevenly. And do they need adjusting after every pass?
Anyway, more progress today. Milled a hole into each cage, then pressed them into the heads. I made a couple of valves, both with different seat angles and they both seal fine?? The valves are rubbish because I'm not happy with the stems, but I'll employ some of the methods mentioned here. 
Cheers all


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## Parksy (Jan 14, 2016)

Attempted another valve and it turned out OK. But I threaded the end and I'm not sure if I like it or not. How do the E-clips hold up in this application?
I tested the valve by blowing as hard as I could into the port and all is good at the moment. Is this acceptable for an engine to run? I haven't lapped it and I'm sure there's probably more acceptable methods of testing it.


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## petertha (Jan 14, 2016)

stevehuckss396 said:


> I make valves using O1 drill rod (silver steel).


 
Now that's good info to know Steve. I've often wondered what the rationale behind stainless was to begin with. Have you tried both & concluded O1 was better for any particular reason? Or you just tried it, worked well & called it good? While we're at it, what is your valve cage/seat material of choice in conjunction with O1?


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## Swifty (Jan 14, 2016)

Parksy said:


> Attempted another valve and it turned out OK. But I threaded the end and I'm not sure if I like it or not. How do the E-clips hold up in this application?



E clips on valve stems are fine, the ones that I have made have used a washer with a shallow recess to contain the E clip to stop it slipping off.

Paul.


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## Parksy (Jan 15, 2016)

Cheers Paul! That is good to know.

I made a couple of valves today and they turned out great! I used a steady rest and was able to machine the valves along the entire length without supporting the end. Worked well. I think when using the steady rest, it requires a lot of practice. But I think I'm getting better. I might mod mine and incorporate ball bearings. At least this will give me an indication on whether it's doing its job or not.

Cheers


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## Parksy (Jan 15, 2016)

Finished the flywheel today, well mostly. It started as flat aluminium bar that I turned down on the lathe. Cheaper than buying large diameter rod. I intend to fill the inside edge with lead to give it more weight. I still need to do this, but now I can at least spin the engine by hand. Am I strange for blocking the ports and spinning the engine to make popping sounds? Can't wait to hear this thing roar into life(hopefully).


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## Parksy (Jan 16, 2016)

Had a go at making cams. Never done anything like this before but the process was very straight forward and I remember seeing it done on the mill with a rotary table. Worked well. Made out of tool steel. Nothing radical with regards to timing. I milled the exhaust lobe first, then 90 degrees later, milled the intake. Sound about right?


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## Parksy (Jan 22, 2016)

Mounted the Dremel onto the tool post holder and used this to grind the taper out of the valves and I'm totally impressed. It worked very well and it's easy to get accurate.



Made 2 in a row successfully. On a roll!


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## Parksy (Jan 26, 2016)

First 8 valves completed and installed. Decided to just use a nyloc nut as the fastening device. No fear of these coming off. I've loosely installed some glow plugs to see what kind of compression it's producing and despite the air hissing out of the glow plug holes, it's bouncy. When it comes to the compression side of things, I didn't give much thought about it except to leave little to no clearance from the piston to the head and utilise a gasket to achieve what ever required height and compression. 



http://youtu.be/RH8PjumJBBA


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## petertha (Jan 26, 2016)

Parksy said:


> I didn't give much thought about it except to leave little to no clearance from the piston to the head and utilise a gasket to achieve what ever required height and compression.


 
I don't think the piston 'closeness' is a huge issue itself, but the compression ratio is for typical methanol/glow. What do you figure your CR (max) is now without gasket shims?


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## Parksy (Jan 26, 2016)

Without the shims, according to the maths, it's about 9.62:1. With a 0.5mm shim, this takes it down to 8.2:1.


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## Parksy (Jan 28, 2016)

Was wondering what everyone does for carburation for these types of engines? Do you make your own carbies? I haven't done much research on vapour carburettors, but the concept is simple and would be simple to make. Do these have rapid throttle response compared to a conventional carburettor?


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## Parksy (Jan 31, 2016)

All valves done, and lapped into their respective positions.


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## petertha (Jan 31, 2016)

Very clean. Its coming along nice. I don't know what to suggest about carb(s) on that configuration. I'm miles behind you.
Heres some reference models
http://www.cad-jung-shop.de/epages/...729/Categories/Baupläne/Bauplane_Modellmotore


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## Parksy (Feb 1, 2016)

Thank you Petertha.

I don't suppose I could get this thread moved to a more appropriate section of the forum(ie build thread)?

Cheers


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## Parksy (Feb 2, 2016)

Gday all

I'm getting my head around cam timings by looking at drawings and I think it makes sense to me. I found a drawing by George D.Britnell which shows intake total open of 220 degrees, exhaust total open of 230 degrees (crank degrees btw) and valve lobe separation of 97.5 degrees. This I understand and should be able to construct, I am just curious if this would suit a nitro v8 engine. I'm not after a revving monster, more a slow runner.
How does the lobe separation and valve open periods effect the engine performance?
Thank you all. My engine knowledge is growing vastly thanks to this page and its members.

Andy


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## stevehuckss396 (Feb 3, 2016)

The effect on cam lobe seperation

widening lobe separation will do the following

Raise Torque to Higher RPM
Reduces Maximum Torque
Broadens Power Band
Reduce Maximum Cylinder Pressure
Decrease Chance of Engine Knock
Decrease Cranking Compression
Decrease Effective Compression
Idle Vacuum is Increased
Idle Quality Improves
Open Valve-Overlap Decreases
Closed Valve-Overlap Decreases
Natural EGR Effect is Reduced
Increases Piston-to-Valve Clearance




If you want a good running V8 I would suggest about 280 degrees open
with 110 degrees lobe separation. Give you a nice warm sounding engine
with a good idle under 1000 RPM. Sound about like this.

[ame]https://www.youtube.com/watch?v=FnbwsLysqGk[/ame]


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## Parksy (Feb 3, 2016)

That is just an amazing looking and sounding engine! Thank you for your help and figures. With those figures, are the exhaust and intake lobes the same(280 degrees open)?
Are the valves opening at any specific point?

Thank you again Steve.


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## stevehuckss396 (Feb 3, 2016)

Cam timing in the V8


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## Parksy (Feb 3, 2016)

Brilliant. Thank you Steve.


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## canadianhorsepower (Feb 4, 2016)

stevehuckss396 said:


> Cam timing in the V8


Hi Steve 
where does the program came from ?? 
looks pretty good

cheers


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## hussien95 (Feb 4, 2016)

stevehuckss396 said:


> Cam timing in the V8



What is the name of this program please&#1567;


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## stevehuckss396 (Feb 4, 2016)

I wrote the code many years ago.

Sorry I cant post the program. Got this error.

EngineCalc.zip:
Your file of 3.90 MB bytes exceeds the forum's limit of 3.81 MB for this filetype.


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## canadianhorsepower (Feb 5, 2016)

stevehuckss396 said:


> I wrote the code many years ago.
> 
> Sorry I cant post the program. Got this error.
> 
> ...



Can you PM it
it looks good


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## stevehuckss396 (Feb 5, 2016)

canadianhorsepower said:


> Can you PM it
> it looks good




I don't think I can. Anybody who wants a copy Email me at [email protected] with the subject engine calculator and I'll send it to you. Double click the setup.exe file and it will install.


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## Parksy (Feb 6, 2016)

More progress. Will hopefully start on some rocker arms tomorrow.


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## Parksy (Feb 7, 2016)

Made the rocker arms today. Started with some steel bar, cut them, machined to shape, filed the contact tip by hand then case hardened it. I will nickel plate them when I get a chance. Happy with my progress.


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## michael-au (Feb 7, 2016)

Good work on this engine, looking forward to seeing it run

Michael


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## Parksy (Feb 8, 2016)

Thank you Michael.

Nickel plated the rockers today.


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## petertha (Feb 8, 2016)

Prior posts on timing with some methanol examples. But I think you have some better qualified input already. Another thing I've noticed that sometimes gets glossed over in cam discussions is the Rocker ratio + Pushrod & Lifter geometry possibly acting at 3D angles + any clearance gaps between lifters etc.... can all affect end result timing in terms of valve physically opening & closing. I'm not sure by how much or if it makes a hill of beans difference, but just mentioning FWIW.
http://www.homemodelenginemachinist.com/showthread.php?t=21808
http://www.homemodelenginemachinist.com/showthread.php?t=17093


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## Parksy (Feb 9, 2016)

Thanks Petertha. I have thought all about those things you've listed and it does worry me if I don't do thinks correctly. But I have tried to keep things as simple as possible. The rocker ratio, which I'll be honest, I don't understand, but assume it is in reference to where the pivot point is in the middle of the rocker? I've kept this in the centre so I'm assuming this gives me a 1:1 ratio.


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## petertha (Feb 9, 2016)

I think I jumbled too many things in one sentence. The rocker ratio I think is just a teeter-totter. If the valve side length = pushrod side length then resultant valve lift = pushrod displacement. If the rocker axle is not centered, for example pushrod side is 0.8" and valve side is 0.7", then the valve lift will be reduced 0.7/0.8 (87.5%) of pushrod displacement. So this  doesn't affect intake/exhaust timing, just lift.

But where this gets funky is how the cam throw acts through the pushrod/tappet assembly onto the rocker because typically these components don't line up all neat & perpendicular and sliding faces & sockets etc. There could well be some 3d geometry acting through the assembly as a whole. So just designing a cam profile to yield open/close duration (in isolation of the other components) may not yield exactly the same open/close timing at the valve itself. Again, whether this is small or large or worth fretting about is another subject. Hope that clarifies what I was trying to say.


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## Parksy (Feb 10, 2016)

That makes sense Petertha.

Thanks for the clarification.


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## Parksy (Feb 12, 2016)

More progress. Machined the cams out tool steel. Went with the 280 degree intake and exhaust duration with 110 degrees lobe separation. Will heat treat them when I've finished cleaning them up. What is the preferred liquid to use for quenching this type of steel? I believe it's oil hardened silver steel.


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## 10K Pete (Feb 12, 2016)

If it's O1 steel then..... oil!!!  1575*F, quench in room temp oil, temper to suit.

Pete


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## Parksy (Feb 12, 2016)

Cheers Pete

Quenched them with oil and they are super hard. Can't file them any more.


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## 10K Pete (Feb 12, 2016)

Now put them in the oven at 600*F (most will go that high) for about an hour.

Pete


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## Parksy (Feb 15, 2016)

Cheers Pete!

Testing the cams. No piston contact! Was my biggest fear, but all is good and compression is excellent.


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## Parksy (Feb 15, 2016)

Probably another obvious question, but I've made this engine with a cross plane crank and each journal is 90 degrees apart. The cams I've made will have flats machined onto a shaft and held in place with a set screw. Are these flats machined at 45 degrees apart or 90?


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## Parksy (Feb 19, 2016)

90 degrees. Got it.

Anyway, more progress. Clevis links, pushrods and tappets are all made and installed.


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## stevehuckss396 (Feb 19, 2016)

Parksy said:


> Probably another obvious question, but I've made this engine with a cross plane crank and each journal is 90 degrees apart. The cams I've made will have flats machined onto a shaft and held in place with a set screw. Are these flats machined at 45 degrees apart or 90?




Are your cylinder banks 90 degrees apart? If so I can give you the cam angles. Have you decided on a firing order?


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## Parksy (Feb 19, 2016)

With regards to cylinder banks, are you referring to the V angle? If so I can't remember specifically what it is as I had to work it out with what materials I had on hand. Does this angle play a part in timing?
The crank throws are 90 degrees apart.
Timing I haven't worked out yet.


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## stevehuckss396 (Feb 19, 2016)

Parksy said:


> With regards to cylinder banks, are you referring to the V angle? If so I can't remember specifically what it is as I had to work it out with what materials I had on hand. Does this angle play a part in timing?
> The crank throws are 90 degrees apart.
> Timing I haven't worked out yet.




Yes the V angle will change things. If the V is not 90 degrees it can change cam timing and also ignition timing as far as when a cylinder needs to fire. You may need to make a custom distributor cap where the studs are not 90 or make a funny shaped copper strip on your rotor. Or will this be fired on glow plug?


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## Parksy (Feb 19, 2016)

Will be a glow engine for starters. When I've got my head around the ignition side of things I'll convert it.


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## stevehuckss396 (Feb 19, 2016)

Parksy said:


> Will be a glow engine for starters. When I've got my head around the ignition side of things I'll convert it.



You will still need to measure the "V" angle so the cam lobes can be set correctly.


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## Parksy (Feb 19, 2016)

I understand how the v makes a difference now that I think about it. 

My initial plan with timing was this... Because it has two cam shafts, one for each bank, I was going to set the cam lobes at 90 degrees on the cam shaft, then time both sides accordingly. So really it's like two 4cylinder engines mounted together and the v angle isn't a factor to consider. 

I hope this makes sense. Does this sound feasible?


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## stevehuckss396 (Feb 19, 2016)

It sounds like it would. Might have a real unique sound when running. Have you decided on a firing order.


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## Parksy (Feb 19, 2016)

That I haven't worked out yet.


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## pickleford75 (Feb 19, 2016)

With a flat plane crank... depending on how you number your cylinders..... there really only 4 pontential fireing orders..... already been down this road.... assuming that your crank is made in the traditional manner


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## Parksy (Feb 19, 2016)

Iv made this crank as a cross plane crank.


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## pickleford75 (Feb 19, 2016)

after going back an rereading i see that it is made in with 4 90 deg throws.... that still isnt too bad.... been down that road.... brings it up to only 16 poss combos


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## pickleford75 (Feb 19, 2016)

one of my v8s has a flat plane and the other is a cross plane... had to sit down with a notebook and a protractor:wall:


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## Parksy (Feb 20, 2016)

pickleford75 said:


> after going back an rereading i see that it is made in with 4 90 deg throws.... that still isnt too bad.... been down that road.... brings it up to only 16 poss combos



Hahaha oh great. Well that's good to know. I think.


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## Parksy (Feb 21, 2016)

Well the firing order side of things has turned out to be a lot more complicated than I first thought. And at this stage I really have no idea. I was wrong about machining the flats at 90 degrees on the cam shaft to mount the cams. They should (I think) be set at 45 degree intervals. But again, this will change the firing order depending on how I put the flats onto the shaft. If I do it this way, it will simply fire in order eg 1 2 3 4 5 6 7 8.




If anyone can provide assistance on this, I'd really appreciate it. I'm pulling my hair out with this one.
I hope my problem actually makes sense to start with...


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## gbritnell (Feb 21, 2016)

The best thing to do in regard to this timing issue is to make a drawing. Start with whichever cylinder you're going to call #1, front left or front right. Now the crank will be rotated 90 degrees clockwise while looking from the front of the engine. (with a 90 degree bank angle) Now find whichever throw is at TDC. This would be your firing order #2. You should pick a cylinder order that kind of moves around the block. By that I mean not just 1,2,3,4 etc. Continue doing this until you make 2 complete revolutions which will bring you back to your starting point. Remember the cams are only turning at half speed to the crank so their rotation is 45 degrees to the crank's 90 degrees. 
gbritnell


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## canadianhorsepower (Feb 21, 2016)

George 
mention everything there is to mention regarding
the Crankshaft firing order.

The fact that you seam confuse a bit I would remove the head
and forget about the cam timing.

Then when you have your firing order all set you can make 
new cams accordingly. It might be a set back but with all the nice work
you did so far I think it would worth it. 

good luck


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## pickleford75 (Feb 21, 2016)

Parksy said:


> Well the firing order side of things has turned out to be a lot more complicated than I first thought. And at this stage I really have no idea. I was wrong about machining the flats at 90 degrees on the cam shaft to mount the cams. They should (I think) be set at 45 degree intervals. But again, this will change the firing order depending on how I put the flats onto the shaft. If I do it this way, it will simply fire in order eg 1 2 3 4 5 6 7 8.
> 
> 
> 
> ...



Id be happy to offer any assistance I can


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## Parksy (Feb 21, 2016)

Thank you all for your input. I appreciate it. At this stage the camshafts aren't fixed to the shaft, so I'm able to modify them in any which way to manipulate the firing order.

I had a search through my rough sketches that I did and found that the v bank is 112.9 degrees. I really should have made it 90 to make things a lot simpler, but this factor mearly skipped my mind.

Pickleford, if there's anything you could add that would help, I'd appreciate it.

Cheers again all

Andy


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## gbritnell (Feb 21, 2016)

I went back through all the posts and in post #14 there is a picture of the crankshaft. I know that pictures can sometimes be deceiving but the cranks throws don't look to be at 90 or 180 to each other. If I'm wrong I stand corrected but the angle of the throw in second cavity looks a little bit different than the last cavity. I also did a layout with a 112.90 cylinder centerline spacing and it looks really flat. Your pictures don't seem to show that wide of a separation angle. I'm only bringing these points up so that I can help you solve your cam timing issues. I'm not doing it to question what you have done. Let's say your crank is in fact a 90 degree crank and your cylinder spacing is 112.90 degrees. It won't be a problem to time the cams for each cylinder but it's sure going to have and odd firing order. 
Let's make the first cylinder on the right bank looking from the top as #1 and the other 3 cylinders on that bank as 2, 3, and 4. Now that makes the first cylinder on the left bank as #5 and the rest on that bank as 6, 7, and 8. 
Cylinder #1 fires. Now the crank turns 112.90 degrees and #5 fires, but being as the crank has 90 throws one of the other cylinders is going to fire when the crank has only turned 90 degrees so you will have that 90 firing space then a 22.90 degree firing space. 
The engine will still run but it will have an odd staccato with the cylinder bank angle versus the crank angle. 
gbritnell


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## Parksy (Feb 21, 2016)

Thanks Gbritnell. I have to apologise about the angle I quoted, I misread my drawings. It should be 67.1 degrees. Which still gives an odd firing pattern.
The crank throws are at 90 degrees.
So if looking at the engine from the front, the front cylinders crank throw is at the top, 3 and 4 are to the right, 5 and 6 are at the bottom and 7 and 8 are to the left. Ive planned the engine to rotate counter clockwise when viewing from the front.
I believe the firing order will be 1-4-3-6-5-8-7-2. (I think)
Now I just need to work out where to machine the flats on the shaft to mount the cams...


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## stevehuckss396 (Feb 21, 2016)

OK here's what I came up with.

With the current crankshaft configuration and a CCW rotation I came up with 8 possible firing orders.

Looking at the front of the block the right hand bank being 1-3-5-7 and the left bank being 2-4-6-8 front to back. (im a chevy guy)

1-2-5-7-8-3-4-6
1-2-4-7-8-3-5-6
1-2-5-6-8-3-4-7   These 3 are not too bad

1-2-4-6-8-3-5-7
1-3-5-7-8-2-4-6

1-3-4-7-8-2-5-6  not too bad

1-3-5-6-8-2-4-7
1-3-4-6-8-2-5-7

No matter which one you choose there will be an uneven firing of the cylinders. Your idea will work fine if you treat both banks as separate 4 cylinder engines.
Cant wait to hear it running. Should have a real unique sound to it.


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## Parksy (Feb 21, 2016)

Thank you Steve, this helps me out greatly. I have chosen your first firing order that you have given me and tested it by using a tool down the glow plug hole and feeling for top dead centre on each piston and it works out. Will be an odd firing pattern but now I know how it works.

Now for working out cam flats to set the cams onto with a set screw. What I have worked out is cylinder 1 (using steve's cylinder numbering) will be at 0 degrees, cylinder 3 is at 135 degrees, 5 at 45 degree and at 90 degrees. Hopefully this will set the cams up where they need to be. But I'll need to triple check this.
I must admit I didn't think about the timing side of things and it's a lot more complicated than I first anticipated.


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## stevehuckss396 (Feb 21, 2016)

if 1 is zero then 5 is 90, 7 is 135 and 3 is 225 degrees from one.
if 2 is zero then 8 is 135, 4 is 225, and 6 is 270 degrees from two

Dont cut flats until you verify.


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## Parksy (Feb 21, 2016)

Thanks Steve. I appreciate this a lot! I need a degree wheel I think. Getting myself way too confused.


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## Parksy (Feb 21, 2016)

stevehuckss396 said:


> if 1 is zero then 5 is 90, 7 is 135 and 3 is 225 degrees from one.
> if 2 is zero then 8 is 135, 4 is 225, and 6 is 270 degrees from two
> 
> Dont cut flats until you verify.



Ok, I Have worked out how you got these numbers. And it's quite simple. Feeling simple at the moment. :wall: 
But at least now I know.

How did you work out the different firing orders? I only ask because this knowledge will assist me later on with different engines and future projects.


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## stevehuckss396 (Feb 22, 2016)

Parksy said:


> O
> How did you work out the different firing orders?



You have to work out when the cylinders are at top dead center. If 2 cylinders are top center at the same time they can be swapped. In your case 1 & 8, 2 & 3, 4 & 5, and 6 & 7 are at TDC at the same time. With 1 being your anchor or Zero degrees, turn the crank 90 and 2 & 3 are up so your FO can be 1 - 2 or 1 -  3. Next 90 degree turn of the crank brings up 4 & 5 So...

1 - 2 - 4
1 - 2 - 5
1 - 3 - 4
1 - 3 - 5

and so on and so on


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## Parksy (Feb 22, 2016)

Thanks Steve. Now I understand, and again so simple. That or you are good at explaining things.

Anyway, I've machined the flats for the cams and timed the engine. All is well at this stage!

Thanks again.


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## driller1432 (Feb 23, 2016)

Parksy
Nice engine I have been following your build beautiful work. I thought I would throw in my 2 cents worth on firing order. From looking at crank picture it looks like front and rear throws are on same index and middle 2 throws on same index with 180 degrees apart from end throws to middle throws hence a 4 cylinder crank. So I agree with Steve to look at it as 2 four cylinder engines each bank a separate engine then you could use 1-2-5-6-3-8-7-4 as firing order then both cams would be the same lobe configuration. 
Stephen


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## Parksy (Feb 23, 2016)

Thanks Stephen. I didn't even think about that, cheers for the heads up. I won't be able to use that firing order though because I've already machined the flats on the rod and at this stage I'm getting impatient and just want a running engine.

I'm a little disappointed in myself in that I didn't research enough and use a proper v8 crank configuration and v angle. But anyway, I'll just have to make another engine then I suppose.


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## Parksy (Feb 23, 2016)

Ran the valve train in for five minutes using a Dremel. I posted this in the "valve seal" thread but In case anyone has missed it here's a quick video
http://youtu.be/lT4v_F-eoXg


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## Parksy (Feb 24, 2016)

Needed a method to start the engine. I was kidding myself when I thought I could rotate the flywheel by hand. Electric drill will be my starting method.


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## Parksy (Feb 26, 2016)

The chain needed a method of tensioning, so i made an adjustable bracket that had a PTFE wear surface for the chain. I made the bracket so i could add a spur gear to it at a later point. Engine is timed and tested it with an electric drill. All is good at the moment. Some of the glow plugs are leaking slightly, but i'm too worried to tighten the plugs that little extra in fear of stripping the threads.















https://youtu.be/V1Ip0PmOdVQ


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## canadianhorsepower (Feb 26, 2016)

Parksy said:


> > The chain needed a method of tensioning, so i made an adjustable bracket that had a PTFE wear surface for the chain. I made the bracket so i could add a spur gear to it at a later point. Engine is timed and tested it with an electric drill. All is good at the moment. Some of the glow plugs are leaking slightly, but i'm too worried to tighten the plugs that little extra in fear of stripping the threads.
> 
> 
> 
> ...


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## Parksy (Feb 26, 2016)

It's going to be a single carb setup. I will use stainless steel tube for the eight cylinders and bend them accordingly to meet in the middle to meet at a common manifold where the carb will be mounted. This is the plan anyway. Could change.


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## canadianhorsepower (Feb 26, 2016)

Parksy said:


> It's going to be a single carb setup. I will use stainless steel tube for the eight cylinders and bend them accordingly to meet in the middle to meet at a common manifold where the carb will be mounted. This is the plan anyway. Could change.




why stainless steel ??

home made carb or purchase one ??

what did you end out with firing order??


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## Parksy (Feb 26, 2016)

Chosen stainless because I want to stay with the silver coloured theme. If it proves to just be a pain when bending then I may change my mind. But so far I haven't had any dramas with it. 

I've cheated with the carby and have purchased one. This will make things a lot easier especially considering that I haven't built an IC engine before. Im assuming there will be a lot of troubleshooting when it comes to starting.

I went with steves first firing order that he listed. Not for any particular reason, it was just the first in his list.
1-2-5-7-8-3-4-6


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## Parksy (Feb 26, 2016)

I am curious, is stainless a frowned upon material to use? Seen a lot of comments from people not exactly praising the use of stainless steel and am curious if there was any merit to this?


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## petertha (Feb 26, 2016)

I'm watching closely & collecting tube bending ideas as we speak. The SS issues seem to be work hardening leading to kinks & cracks. But everyone's radius / tubing od / wall thickness / alloy / geometry & methodology is a bit different, so hard to compare apples & apples amongst the projects.
http://homepage2.nifty.com/modelicengine/k070402.htm

If you've done this already, would love to see your setup. Personally I've decided to ease into it with brake line tubing on my radial. The induction manifold has some funky curves. The exhaust stacks are just little curved stubs & could probably be SS. But aside from discoloration the brake tube should take the temp ok.


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## Brian Rupnow (Feb 28, 2016)

Parksy--I have been following your build for some time now, and I must say, your engine looks really good. You have certainly taken on an ambitious project, and I wish you success with it.----Brian in Canada


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## Parksy (Feb 29, 2016)

Thank you Brian. I appreciate your kind words. It's getting close to finishing and I'm getting nervous about whether it will run or not.


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## Parksy (Mar 6, 2016)

Spent the last few times in the shed tying up loose ends. I pulled the engine apart to sort out a couple of leaking valves. The majority were good, but one was particularly bad. My findings is fine lapping compound, followed by a thorough clean, then some metal polish then another thorough clean works fairly well. A simple clean seems to help a lot with valve seal.
I chucked the heatsinks onto the rotary table and cut some fins using a slitting saw. I probably should have gone deeper and used a thicker blade, but we shall see. I must commend those who can achieve perfectly spaced and sized fins. Despite turning the controls with as much accuracy as possible, I still had a few unevenly spaced fins. But never mind, I like the look. Maybe I need to practice some more to improve accuracy.
I've started on the intake. At the moment it consists of two plates clamped together, which I've hollowed out and made an adapter to fit a carburettor that I purchased from a hobby shop. The plan is to use stainless tube to attach it all together. I found some stainless tube from an eBay seller in Hong Kong that bends very well simply with a bender, and if I try hard enough, by hand. I'm just waiting for more to arrive.
Anyway here's some pics. Getting close.


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## Parksy (Mar 6, 2016)




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## stevehuckss396 (Mar 6, 2016)

Cant wait to hear it pop. Keep us posted.


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## petertha (Mar 6, 2016)

You've sure done some nice work there Parksy. Best of luck on the home stretch. And the finning looks good from over here!

The only thing I can pass on from my own RC nitro engine experience is the cylinders are actually relatively cool. They primarily see conductive heat from the heads. Finning is nice & certainly can only help. But the heads are where temperature is maximum. The cylinder barrels see this heat conductively. The heads see it almost directly being adjacent to combustion. In aircraft engines, head fins are still necessary to increase ambient surface area even though they receive perpetual cooling blast from propeller. In the stationary engines, with the absence of this airflow or liquid cooling, the fins become ginormous in order to dissipate this heat. I think this was discussed before but just saying keep an eye on it. Bad things happen when the heads cook.

_I found some stainless tube from an eBay seller in Hong Kong that bends very well simply with a bender, and if I try hard enough, by hand_

I'd love to hear what specific tubing you got, shapes you managed to bend, tooling pics etc.


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## Parksy (Mar 6, 2016)

Thanks Petertha. The temp side of things will get monitored religiously when (if) it starts. I've noticed that four stroke nitro engines aren't as radically finned as the two stroke versions, but if need be, I'll mill some fins into the heads to sort that out. 
I'll post some updates on the stainless, but I'm still waiting for it to arrive. I have some 6mm tubing and it is just wonderful to bend using just a cheap eBay pipe bender. I've got some 8mm tube (1mm wall) on the way and I'm hoping it bends just as well.

Cheers


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## petertha (Mar 6, 2016)

Sounds good. Re tubing, 'stainless' & 'easy' (bending) never seem to occur in the same sentence. Now I'm super curious what you got there. Keep us posted.


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## Cogsy (Mar 6, 2016)

I don't know how well they bend yet, but I bought some of these LINK to use for exhaust pipes. Nice and cheap and 6mm dia. I've cut and silver soldered them and they work well. Being they've been bent already I'm hoping they'll bend nicely but I'm yet to build a bender.


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## Parksy (Mar 12, 2016)

Thanks cogsy, I've also purchased some to experiment with.

It turns out I didn't purchase enough tube to practice with and I was worried that I would run out. I was able to bend it with the eBay pipe bender, but the radius was too large for what I wanted. 
I found the intake setup to be quite a headache and head scratcher. Didn't make it easy for myself when I drilled the ports on the heads at such an awkward angle. Lesson learnt for next time.
Anyway, lots of measuring and drilling at very strange angles and I was able to come up with a setup that should hopefully work. The two halves are clamped together over the intake tubes which I plan to rtv silicon the halves together to seal it.
I'm not sure if I like the look at the moment, will have to see when it's completed.


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## Parksy (Mar 12, 2016)

Cleaned up the intake, milled some passages internally and installed the carby mount. I was wondering if anyone has any experience with this type of carburettor? It's off a four stroke OS nitro engine and was wondering if I need to mount a fuel tank up higher or at the same level (or lower)?


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## petertha (Mar 13, 2016)

The rule of thumb (4S or 2S glow) is that center of the tank should be about the center of carb fuel inlet spray bar that resides inside the venturi. But this has a lot of other (aircraft related) assumptions baked in that may or may not apply to your setup. But probably a good starting point in any event. This pic might serve as a good reference.

Mid tanking is basically trying to be a good 'average' position for a tank run. Its another way of saying averaging hydrostatic head, which is the vertical column of fuel in terms of equivalent pressure on the fuel stream = the  distance between fuel level (top) and carb inlet (bottom). A full tank will have a slight positive head or higher fuel pressure & the engine may run slightly rich. A near empty tank can have low or no head & run leaner. Its not practical to be adjusting the needle as fuel level varies (and you generally cant in-flight), so a mid position is trying to average these end conditions so to speak. 

If you elevate the exact same tank for example, you increase the head, which increases the fuel delivery pressure. We are talking low pressures psi-wise but actually quite significant in terms of needle valve setting & air/fuel ratio.

But typical RC flight vehicles deviate from stationary bench engines. As the model maneuvers the head can change quite dramatically. Just imagine this same picture rotating to different orientations as in climb or dive & now where is the fuel top & bottom. So its also common to put a pressure tap on the exhaust manifold & pipe this to the tank which gives a bit more positive pressure boost which is additive to fuel hydrostatic pressure. 

Your stationary engine wont have these complicating 'flight' issues, so it really boils down to finding a reasonable tank position & needle valve setting combination that gives a good run & then basically just monitoring fuel level & actual running. The carb of course is seeing slight vacuum pressure from venturi throat airflow & manifold pressure so it can draw fuel at a slightly lower level (within reason). Similarly the tank can be elevated slightly so long as the needle valve can be screwed in & still meter properly. But this also has practical limits. If the tank is too high, fuel can also free flow into the carb / manifold / cylinders especially if engine doesn't start right away. This risks hydraulic locking & bad things can happen with an electric starter. So good to have a shut-off valve or simple line pinch between tank & carb in any event.


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## petertha (Mar 13, 2016)

Ohrdorf V12


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## Parksy (Mar 13, 2016)

Wonderful Petertha. This helps a lot!! I will apply this rule of thumb and go from there. Cheers!!


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## Parksy (Mar 13, 2016)

need to wire up the glow plugs. I have four glow plug drivers and I did try firing with just four. Got a few pops and hot cylinders, but no running. Am I kidding myself trying to run it on four cylinders?


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## Cogsy (Mar 14, 2016)

Well....I once accidentally fired up the 351 Cleveland V8 in my car with 4 leads off and it was difficult to start and seemed like it was running out of fuel - then I remember the 4 plug leads. I'm not saying yours wouldn't run, but it'll be much easier to start on all 8.


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## 10K Pete (Mar 14, 2016)

Parksy said:


> need to wire up the glow plugs. I have four glow plug drivers and I did try firing with just four. Got a few pops and hot cylinders, but no running. Am I kidding myself trying to run it on four cylinders?



A lot of friction to fight but I don't think it would hurt anything to try.:hDe:

Pete


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## Parksy (Mar 14, 2016)

Just need to be patient and do things properly I think. Also need to work out how to tune the carby. Not sure which are the low speed/high speed needles on this carby.


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## petertha (Mar 14, 2016)

Google your model number carb & should get some hits. The fundamentals should be available on-line through OS parts schematic breakdowns (in terms of identifying which screw does what).

There are general procedures along these lines
http://www.osengines.com/faq/product-faq.html#q16

You will probably find both good info & maybe what I'd loosely call mis-information where people are having issues or solving problems that are aircraft orientated & maybe not quite applicable to your specific application. 

I think a new/unknown engine with its own teething pains is an additional consideration to the carb itself, even assuming its set up 100% correct. But I'd say try & get a mid-range rpm running to begin with, then worry about idling & top end as a secondary goal. Generally if the AF mix is out of whack in the mid/high range, it only makes solving low/idle running even more challenging. Double check for air leaks like on the carb throat o-ring/gasket & fuel line leaks like on inlet nipple. 

I also have a feeling 'starting' is a ritual itself with these glow/methanol jobbies. I've ran so many RC engines that were set up perfect. But that was with the classic electric starter. Now if I decided to hand flip the exact same beast, it seems to require more effort & tries to get it going. Then its so tempting to diddling needle valve & adjusting things trying to find a sweet spot. I'm not saying go to starter right away but keep in mind if required. Even something moderate like a low rpm cordless drill will help, especially if its being difficult. Just beware any hint of hydro-locking when using starter. Remove plugs, drain every bit of methanol, resume operations.

Sorry, cant speak to your 4-plug (reduced cylinder) trial with any experience. You're miles ahead of me!


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## Parksy (Mar 15, 2016)

Thank you again Petertha. I do value your input (and others) very much so.

I had another play around with the engine today and found the intake wasn't sealed properly and leaked. I don't know why, but I was pleased that I found this. I'm still having issues with leaking glow plugs also, and I'm too worried to torque them down too far in fear of stripping the thread. Does anyone have any torque figures or rules with torquing glow plugs into aluminium?

I haven't found any plugs or leads that will plug into glow plugs so I'm going to try and make my own out of brass. My main concern is how to retain it onto the plug itself. If anyone has any pointers on this, I'm all ears.

Cheers


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## 10K Pete (Mar 15, 2016)

I know it's a bit late but would Heli-Coils or similar inserts work in the glow
plug threads to help with the torque issue? I mean, would they fit? They would
allow about double the torque.

Pete


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## wirralcnc (Mar 15, 2016)

Are you using annealed copper washers under each glow plug. Shouldn't have to over tighten to get them to seal. As for glow plug leads try just engines.

http://www.justengines.co.uk/acatalog/Just_Engines_Online_Starting_Gear_115.html


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## petertha (Mar 15, 2016)

The plug clips I've used are really pretty simple. I prefer the flat meal ones that have a slit so they kind of pinch the plug terminal. probably what you are envisioning with brass. Copper might be a better choice resistance wise. You just want good contact & vibration proof. The heat shrink or some sort of shroud protects from oil adversely affecting electrical conductivity.

https://www.google.ca/search?q=onboard+glow&biw=1680&bih=999&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiDpPfNp8PLAhUO12MKHf9dBwwQ_AUIBigB#tbm=isch&q=onboard+glow+clip&imgrc=12QTyNjZJe44mM%3A

https://www.google.ca/search?q=onbo...sch&q=onboard+glow+clip&imgrc=CXZNLff4nKQuBM:

For sure you need to use the copper squish washer with plugs. Avoid plugs directly threaded in head threads, they wont seal proper. Torque is gentle hand tighten like with a socket nut driver. Avoid doing this when engine is hot because it can equate to over tightening & thread damage. I don't know an exact in-oz torque but most guys even in HP applications don't bother with those click-off torque handles & just do it by hand & feel.

Also check your grounding & wiring: a new (non oily) plug should light nice & red & stay that way. if its dull or glows sporadically, it could be your electrical wiring, drive battery etc.


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## petertha (Mar 15, 2016)

wirralcnc said:


> As for glow plug leads try just engines.
> 
> http://www.justengines.co.uk/acatalog/Just_Engines_Online_Starting_Gear_115.html


 
Sorry, missed your link. Half way down the web page - that's a nice looking connector, either to buy or replicate.


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## 10K Pete (Mar 15, 2016)

petertha said:


> Sorry, missed your link. Half way down the web page - that's a nice looking connector, either to buy or replicate.



I remember those!! Used that type of clip 55 years ago on my control line planes. Really good. But maybe not for permanent installation.

Pete


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## t.l.a.r. eng (Mar 18, 2016)

Quite by accident I found using some small stiff spring stock will connect to the glow plugs quite nicely.
I was trying to run my Kinner for the first time and was rummaging for a quick dirty way to make it work.  By clipping short lengths of spring and soldering it to the glow wire, it fits the glow plug nicely and won't vibrate off.

When the plugs were first hooked to my homemade glow driver the springs smoked a little bit but still lit up the glow plugs quite nicely. The engine has many runs on it using these springs as clips.


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## Parksy (Mar 20, 2016)

Thanks all for your suggestions. I've taken it all onboard and will work something out. At the moment I'm using a temporary method with alligator clips. Trying to start the engine is a frustrating process especially when using batteries that don't last long. I get a few minutes of glow time then need to recharge. 
Anyway, I tried rotating the engine by hand and I can feel it fire and want to kick the crank in the opposite direction. I'm in the process of experimenting with cam timing and will wire the glow plugs up to a car battery so I can have more time to experiment. Just waiting for some Buck converters to arrive in the post.
I think I'm getting there.


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## Brian Rupnow (Mar 20, 2016)

I'm curious. What is a "Buck converter"?--Brian


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## canadianhorsepower (Mar 20, 2016)

Brian Rupnow said:


> I'm curious. What is a "Buck converter"?--Brian





The buck converter is a very simple type of DC-DC converter that produces an output voltage that is less than its input. The buck converter is so named because the inductor always bucks or acts against the input voltage.


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## Brian Rupnow (Mar 20, 2016)

Thank you Luc.  My first wife was a buck converter. She could convert a buck to 35 cents faster than a speeding bullet.----


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## petertha (Mar 20, 2016)

Parksy, there are more than a few HMEM posts on this subject and similarly related to multi-cylinder glow engines. The topic comes up quite often. You might have to do some keyword query searching but would be worth digesting IMO. 

The solutions vary from ganged single cell batteries to jerry-rigged step down voltages using larger capacity batteries to dedicated circuit boards that do some solid state switching in order to use smaller or more common batteries.

The bottom line is: each plug requires nominal 1.5 volts & current draw between 3-5 amps depending on a bunch of parameters, but probably a minimal guideline for starting mode. So 8 cylinders all lit could draw 24-40 amps. There aren't too many 1.5 volt / 40 amp capable batteries lying around, hence the varied solutions making use of what you have or want to buy. Also, you cant exceed the 1.5v by much or the element will burn out. And you cant be under the 1.5v by much or it wont glow properly.

An important parameter related to cells (of any chemistry or shape form type) is its C rating. This relates its ability to deliver current as a function of its capacity. So for example a single cell NiMH 1.5v battery of 2000maH capacity and C=5  means it deliver 1.5 volts at 10 amps discharge (5C * 2A) for 1 hour. So it could power 2 plugs at 5A simultaneously for one hour before dying/requiring recharging. Or light 1 plug for 2 hours. C is dictated mostly by cell chemistry, internal resistance...another topic. But just be aware of 'max amps' spec & you get the same answer.

C-rating also relates real world voltage decay. For example a AA penlight battery may well deliver its 1.5volts at 20 mA load to light an LED. But push 4-5A though it & the voltage will decay so maybe 0.7 volts. Which is hard on the battery & wont properly light the glow plug element.  

These days you can buy high-C, high-capacity, lithium polymer packs dirt cheap. This one will deliver 200amps! (40C * 5A). But... lithium comes in 3.7-4.0 nominal voltages, not 1.2-1.5 volts like NiCD NiMH. So Lithium cells have the power no problem, but voltage exceeds glow plug 1.5v requirement, so we are back to some sort of step-down requirement.
http://www.hobbyking.com/hobbyking/store/__18562__Turnigy_5000mAh_1S_40C_Lipoly_Single_Cell_.html

The big car battery solution works no different. It has a huge capacity so the 40A current load just tickles it. However its 12-14v nominal, so you need something in the circuit to step down to 1.5v. Hope this helps!


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## t.l.a.r. eng (Mar 21, 2016)

petertha said:


> The solutions vary from ganged single cell batteries to jerry-rigged step down voltages using larger capacity batteries to dedicated circuit boards that do some solid state switching in order to use smaller or more common batteries.
> 
> The bottom line is: each plug requires nominal 1.5 volts & current draw between 3-5 amps depending on a bunch of parameters, but probably a minimal guideline for starting mode. So 8 cylinders all lit could draw 24-40 amps.



I used two chips as a basis for my Kinner glow driver from http://www.jamesengine.com/index.htm 
Using 12 volts and pulsing the on time at the plug to get the 1-1/2 volts.

 The amperage stays around 4 amps for a 5 cylinder, so a v-8 may only need 6 amps or so to operate.


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## petertha (Mar 21, 2016)

TLAR - thanks for link reminder. That's the one I was looking into for my 5-cyl when I get that far. I was trying to say for basic batteries, the current draw per plug is more than people typically expect & the 1.5v is a rather narrow voltage window. The pulse timed / circuit board solutions are the way to go IMO. 

Question for you - that circuit design that presumes input 12v source, how much leeway can the voltage be? For example my gel cell utility battery is probably closer to 13-14v resting. Do you just mean 12v 'nominal' like how we loosely describe car auto batteries, or it has to be quite close to 12v like of a DC power supply? Another reason I ask is a 3S lipo pack at 3.7-4.0v / cell is real close to that (11.4-12.3v) & would be a perfect & inexpensive matchup.


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## t.l.a.r. eng (Mar 21, 2016)

I realized you were talking straight dc voltage, but wanted to share what the pulsed amperage would be. 

At the time I built my circuit Jerry was offering just the chips and i built my circuit around two of them from him. I don't know if he offers parts only or if completed circuits only now? He has an e-mail on his site.

The 5 cylinder driver I built used two chips and used non adj resisters to come up with the output. The circuit works well except for the heat given off the output transistors will cause the voltage to run away if not cooled and heat sinked properly. So heat sinks on the outputs and a computor cooling fan to blow across them works great. The glow driver is on anytime the engine is running to prevent any cylinders from droping out.

The driver I made will run [that I know] on 10 volts to 16 volts with no effect on the glow plugs. I suspect the 5 volt voltage regulator to operate the chips would be the reason for that, and the wide range of the output transistors.

I have noticed that the new drivers listed on his websites are a redesigned version using mosfets eliminating the need for heatsinks.


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## Parksy (Mar 24, 2016)

I have been able to drive all eight glow plugs using a couple of Buck converters and a car battery. Unfortunately I haven't had much luck starting the engine. While turning it over with the drill, all eight cylinders get nice and hot, unfortunately no firing under its own steam. 
Might have to give it a break for a little while before I get too frustrated with it.


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## dsage (Mar 24, 2016)

What rpm are you turning it over at?
Faster might be better until it break in a bit.
Might be just a change to a different drill required (if that's what your using)

Sage


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## Parksy (Mar 24, 2016)

Cheers sage.

I've tried it with a couple of different drills for this reason thinking that I wasn't spinning it fast enough. Even at 3000 rpm. Still no luck unfortunately.


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## canadianhorsepower (Mar 24, 2016)

Parksy said:


> Cheers sage.
> 
> I've tried it with a couple of different drills for this reason thinking that I wasn't spinning it fast enough. Even at 3000 rpm. Still no luck unfortunately.



What fuel are you using
It should puff and huff a little


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## Parksy (Mar 24, 2016)

Using pre mixed nitro fuel. It does huff and puff and get hot. I'm wondering if regular spark ignition will solve my problems.


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## canadianhorsepower (Mar 25, 2016)

Parksy said:


> Using pre mixed nitro fuel. It does huff and puff and get hot. I'm wondering if regular spark ignition will solve my problems.



and your final CP /r is


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## Parksy (Mar 25, 2016)

I believe it's about 8:1, but this is according to the maths. Real life figures could vary. I should test with a gauge. What sort of PSI should I achieve?


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## dsage (Mar 25, 2016)

I guess with glow plugs you have no control of timing. Does it "fight back" when it fires or does it just go through the motions and get hot. I guess if it's not fighting back but it is getting hot then it is burning fuel and it seems reasonable it would fire at maximum compression. So my assumption is it is not producing enough power to overcome it's own friction. It might need more fuel to increase the power or a higher nitro mix.
 Try a spray of starting fluid. It should at least react differently on that. If it attempts to run then it might just be a carb adjustment.
 I'm not sure what compression you SHOULD have but if you think it is 8:1  then it should be somewhere around 8 x 15 psi = 120 psi. But that's going to be highly theoretical as well. Cam timing / rings / cranking speed etc. etc. are going to drastically affect that. Are you sure your cam timing is proper? I would expect for that engine you'd want the intake valve closed very near (if not before) bottom dead center to get maximum compression.
 I've never built a nitro engine. Are they supposed to run like a diesel or model airplane engine? With no control of timing (or compression) how do you control when it fires?

Sage


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## petertha (Mar 25, 2016)

dsage said:


> I guess with glow plugs you have no control of timing... Are they supposed to run like a diesel or model airplane engine? With no control of timing (or compression) how do you control when it fires?
> Sage


 
There is no compression 'control' in a glow engine. (Or maybe you are referring to what are loosely labelled diesels with the tommy bar?)
Aside form these, regular glow engines are the same as any spark conventional gasoline engine in this regard. Once the parts are machined & assembled, the resultant physical geometry dictates CR. You can tweak it up/down with head shims or skimming surfaces no different than most engines, but by & large the (mathematical) compression is set once assembled. One small exception, glow plugs come in long & short & mid range lengths & copper washers. So if this incremental volume (which occurs in the threaded section) is a large percentage of head volume, it can affect CR. But a displacement of this size I wouldn't think is hugely significant presuming the true CR is in the ballpark.

The glow plug element type + fuel composition + compression + I/E factors collectively affect ignition timing. Once you get the magic recipe, it just works, 2S or 4S. If any of the above is too far out of range, it frustratingly wont work. The trick is to isolate the culprit(s). If you can at least try & mimic the methanol glow engines in existence on this basis (fuel, timing, CR, plugs, carburation) that's probably the diagnostic route. Because there are millions of them out there. Well.. not that many multi-cylinders, but I'm just talking about trying to make a cylinder fire here.

One thing that I cant explain out of inexperience, but can at least point out. The running methanol/glow Vee's I see predominantly seem to have multiple carbs. Yet the same displacement radial glow engines can get away with one carb in the rear, but the same length or longer induction headers going both uphill & downhill without any artificial boost & same I/E timing. There must be a reason for this. I don't think the designers would bother ganging multiple carbs just for the cool factor & even more tuning equalization challenges. Yet OTOH there are examples of model gasoline/spark Vee's with one carb & intake manifolds that are scale reductions of their FS counterparts. ????

http://www.cad-jung-shop.de/epages/62479729.sf/de_DE/?ObjectPath=/Shops/62479729/Categories/Baupl%C3%A4ne/Bauplane_Modellmotore

http://www.engineman.de/


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## petertha (Mar 25, 2016)

Parksy said:


> I believe it's about 8:1, but this is according to the maths. Real life figures could vary. I should test with a gauge. What sort of PSI should I achieve?


 
Might be worth validating this with a syringe of methanol if you haven't already? Its amazing how small variations can affect CR at this scale. 

Fill cylinder volume on top of piston at TDC. Then fill head volume with your existing glow plug assembly in place. Then compare to BDC volume for actual CR. If the physical numbers agree with 8:1 then that's one diagnostic check off your list. But if it turns out to be 6:1 for whatever reason, this will make starting & sustained running much more challenging.

Trying to get gage pressure can be done with the right do-dads & would be good to know, but its a little more involved,


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## Parksy (Mar 25, 2016)

Thank you guys, I appreciate your effort. I will make a compression gauge out of an old glow plug some how and see what I get.

Sage, something you mentioned intrigued me right at the start of your post. When rotating the engine by hand, i can feel the cylinders firing but far too early. So it's pushing the piston back down before its reached TDC. Could this be a factor? It's not far off TDC. I suppose this is where I need to start playing with head shims to set the timing correctly.


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## petertha (Mar 25, 2016)

Were you able to validate valve intake open/close positions relative to TDC like using a protractor wheel? All it would take is a smidge of cam lobe misalignment or tappet gap or pushrods coming off at an angle or rocker ratio... resulting in something different in real life vs. on paper.

Head shims will affect compression but not really advance ignition point a lot on glow. If you are 8:1 now & de-shimmed to 10:1, you'd still be the range of many ordinary RC glow that run at that CR. Increasing nitro % will give you some more pop, but save that for later. If its not sustained running my gut feel is it something more fundamental.

Also, what do the plugs look like when they come out? Light tan? Totally clean & fuel soaked? Dark brown & sooty? Silver grey & distorted wire? These are all signals indicating different issues.


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## Parksy (Mar 26, 2016)

The plugs look brownish on inspection. I didn't use a protractor wheel, instead I looked underneath at the crank to check for tdc for cylinder number one and went from there. A protractor wheel may be a better option I think.


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## Parksy (Mar 27, 2016)

Ok, had another play and one thing that is evident is that I need to work on the cam timing. I played with just one bank, ran with the drill, then connect the battery to drive the glow plugs and it sounded like an engine.
But the problem is that I'm guessing here. Loosen the cam sprocket set screw, rotate a couple of degrees and re tighten. How does one use a degree wheel? 
I initially timed the engine by setting number 1 piston to TDC, then set the intake cam to start open. Then rotate the engine so number 2 was at TDC, and again, intake to just start open. But this setup doesn't work and the engine doesn't run. 
For fun I set the exhaust valves to open on compression stroke. Makes for a very loud engine when rotating with the drill. This sound I was able to replicate when I altered the timing and connected the glow plug drivers. With glow plug drivers connected, the exhaust Sound changed dramatically indicating that I'm actually getting firing, where as before I wasn't(despite thinking I was). But the issue with this is I have no idea where my timing is. This doesn't help my cause at all, so if anyone can point me in the right direction, I'd be very happy.


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## Parksy (Mar 27, 2016)

My firing order is 1-2-5-7-8-3-4-6. Bank angle is 67.1 degrees. So because I'm running two cams, and 2 fires directly after 1, I need to set number 2 cam 33.55 degrees from number 1 cam?


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## grapegro (Mar 27, 2016)

Hello Parksy, A method I used ver many years is to get piston at top dead centre with the two valves rocking, exhaust nearly closed and inlet starting to open. You can check each cylinder in this manner and save a lot of anguish.
Norm


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## Parksy (Mar 27, 2016)

Cheers grapegro. I have set timing to what I think is correct, removed all glow plugs and checked valve openings against piston position. All good in this regard. 

Got close to starting tonight. Played with carb adjustments and got all cylinders firing and hot(very hot). Just didn't want to continue running. Cylinders continued firing even when I disconnected the glow drivers, so long as I continued cranking the engine.
Just need to keep tweaking. 

Cheers


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## Brian Rupnow (Mar 27, 2016)

Try setting it up with your exhaust valve just beginning to open at about 25 degrees before bottom dead center, and the intake valve beginning to open at about 20 degrees before top dead center. The amount of time that the valves actually stay open is dictated by the profile of the cam itself. There is an entire world of science around cams and cam timing, but the numbers I have given you are in the ballpark.---Good Luck.---Brian


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## stevehuckss396 (Mar 27, 2016)

Parksy said:


> My firing order is 1-2-5-7-8-3-4-6. Bank angle is 67.1 degrees. So because I'm running two cams, and 2 fires directly after 1, I need to set number 2 cam 33.55 degrees from number 1 cam?




The best way is to find top dead center of each cylinder and make sure that the exhaust valve is fully open 110 crankshaft degrees before TDC and the intake should be fully open 110 crank degrees after TDC. This TDC is the end of the exhaust stroke and the beginning of the intake stroke. Use a degree wheel. This is not the time for the eyeball method.

Because of the oddball cylinder bank angle I would just check all cylinders individually just to be sure. Shouldnt take long after the heads are off.

This assumes your cam is 110 degrees lobe angle.


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## petertha (Mar 27, 2016)

You're miles ahead of me parksy, but I'm collecting links for when my special hair pulling day inevitably comes. 

Here is a setup pictorial that maybe you can re-jig for your own purposes.
http://philsradial.blogspot.ca/2013/02/valve-timing.html

From other setup pics I think the procedures are similar, but obviously vary by the engine configuration & accessibility. To my eye, for any given cylinder, looks like:

- with an indicator against a reference piston top, measure highest position in bore

- 'mark' that position as TDC. Some use a protractor degree wheel mounted on CS against a fixed pointer reference, some make up their own wheels from cardstock because they have pre-figured out valve I/O clock positions relative to their engine. I think this fellow has a block attached to CS end & then measures rotation with a mag digital level device.

- assemble head & cam/valve assembly

- ?somehow? put indicator on intake or exhaust valve rocker or tappet or some part of the valve train to reliably indicate when valve begins to lift & has closed as the CS is rotated through TDC-BDC motion. Now you have independently validated I/O timing for that cylinder as a function of CS rotation degrees & can compare to original design or whatever.

- now whether that's the end of it for remaining cylinders because the camshaft (or cam ring) and crank throws are fixed as a function of how they were machined & assembled, or how that relates to firing order I/E on other cylinders I cant say. But one should be able to repeat this procedure for remaining cylinders & relate it to the #1 cylinder TDC reference if that original position can be preserved. 

Hope I've got this right, otherwise maybe the experienced guys will correct me.


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## Parksy (Mar 28, 2016)

Thank you guys. Almost had it started today. It ran for a couple of revolutions. Had condensation form on the intake it got so cold. Unfortunately the loctite holding the crank together hasn't held up and the flywheel now wobbles. This I will need to address before I go any further. I will correct it, but at this stage I'm giving this project a break.

Thank you all for your help. I will have it running eventually.

Andy


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## t.l.a.r. eng (Mar 28, 2016)

You may have posted a clue.  If it is trying to run, open the throttle all the way and use a heavy rich mixture when trying the first start.

If white smoke is coming out the exhaust it is still a little lean. New engines tend to have raw liquid exit the exhaust when running on glow fuel until things settle in. Another clue is when you said it will try to keep on firing without the glow driver.

Open the throttle wide, richen the mixture, and leave the glow driver on and it should run if the cam timing is correct.


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