# Vega V twin Aero engine



## creast (Apr 25, 2014)

After finally completing my Kerzel H&M engine I am now probably getting too ambitious and intend to build a Vega 9cc V Twin.
I have located the articles and at present translating them into SolidWorks to check and refine the build.
Has anyone here any experience of building this engine?


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## weez (Apr 25, 2014)

Do you have any pictures or video of your Kerzel?  I am currently building one.


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## creast (Apr 26, 2014)

weez said:


> Do you have any pictures or video of your Kerzel?  I am currently building one.



Hi Weez,
I will be posting them soon on the finished projects forum. I did post some GrabCad and a link to an earlier video which will be updated soon.
https://grabcad.com/library/hit-and-miss-engine-kerzel-design--1

Good luck with your build and if you need any help then drop me a line. I had a lot of problems over the build duration but have managed to sort them all.

Rich


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## BronxFigs (Apr 26, 2014)

Don't know too much about this V-twin.  Is it a sparker or, glow-plug engine?

Will you be posting details/drawings of your version of the head design, rockers, valves, cages, etc? 

Good luck with the build.


Frank


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## creast (Apr 26, 2014)

Hi Frank,
The original design is for glow plug and that makes it simpler all round. I always re-draw the plans in SolidWorks as it allows me to identify errors which there often are in plans. I will translate these into 2d drawings eventually and will probably do it metric as opposed to the original which is imperial (1986 plans)


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## BronxFigs (Apr 26, 2014)

creast:

Thanks for the quick answers.  Can't wait for the building of the engine to proceed, and, for the 2D drawings, whenever.

Have fun.


Frank


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## petertha (Apr 26, 2014)

creast said:


> I have located the articles and at present translating them into SolidWorks to check and refine the build.
> Has anyone here any experience of building this engine?



Nice! Look forward to your construction. A Vega build thread was posted on HMEM if that's helpful. Looks like last update was Mar-2013.
http://www.homemodelenginemachinist.com/f31/vega-9cc-v-twin-4131/


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## creast (Apr 27, 2014)

Hi Peter,
Thanks for the link.. very useful. I will have to see if the author is still here and can answer any queries I may have. Cheers!


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## creast (Jun 16, 2014)

Well, I have finally started the long haul of making the Vega V twin.
Most of the machining is done where I work and so is done piecemeal at either my lunch break or maybe an hour after worktime. Some machining is done at home on my Myford ML7 but I do prefer the rather worn out Colchester at work for its capacity to remove stock.
The crankcase is almost complete and just requires the holes for the cylinders to be bored out.
The crankshaft is about 90% there and is made from 17-4PH which is pretty strong  compared to the EN8 suggested.
Turning the crankpin wasn't as straightforward, since for the required offset, my 4 jaw chuck bore was too small to allow the shaft to be within the chuck.
The solution was to create a fixture from aluminium bar to hold the crankshaft and then swing that in the four jaw. The whole lathe was wobbling a bit with unbalance but it all went ok. The crank web now requires milling.
So far I spent approx 7 hours to create the two parts to this stage.


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## petertha (Jun 16, 2014)

Very nice machining progress Creast. Just curious, when you did your SW CAD conversion from original 2D paper plans, did the parts & dimensions & assembly come together nicely without errors? Did you make any significant changes along the way outside of metric-ation?

 What's your plan of attack on the piston rings in particular? Did they call for a gap + heat treat jig, or commercial RC-type ring, or..?


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## creast (Jun 17, 2014)

Hi peter,
No it hasn't come together nicely to be honest. There is a lot of information missing from the magazine articles and that becomes apparent when you try to draw it up in CAD. 
Of course there is always the dilemma of trying to round up figures in metric to make it look nicer but that isn't always possible.
also the original drawings are in awful fractions! LOL!
I am still adjusting things as I make it. The original used BA threads and I am trying to avoid that but can see the BA sizes sometimes look better.
Its probably best I make to my drawings and spot the errors in my drawings as I go along before I publish my version.
The rings are pretty normal CI jobs with a heat treat to set. This engine actually use two rings in one groove. No gaps are specified as far as I can see having read it a few times so will play it by ear so to speak.
I contacted a member here who was building one but never completed it so I wonder if it will ever run anyway??? Oh God! 

Regards
Rich







petertha said:


> Very nice machining progress Creast. Just curious, when you did your SW CAD conversion from original 2D paper plans, did the parts & dimensions & assembly come together nicely without errors? Did you make any significant changes along the way outside of metric-ation?
> 
> What's your plan of attack on the piston rings in particular? Did they call for a gap + heat treat jig, or commercial RC-type ring, or..?


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## petertha (Jun 17, 2014)

creast said:


> Hi peter, No it hasn't come together nicely to be honest. There is a lot of information missing from the magazine articles and that becomes apparent when you try to draw it up in CAD. Rich



 Thanks for your candor Rich. You will persevere and it will run! 

 Reason for my question was I think I had those same paper plans many moons ago (without the article, ugh!). I tried replicating the design into 2D cad. Well.. probably a combination of my newbyness, the drawings & dimensions, not visualizing 3D parts assembly properly... I shelved the project before even beginning. Probably why I have more plans & articles than metal shavings & engines... But One Day! ;D 
 Look forward to your progress. Your design iteration will be golden!


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## Niels Abildgaard (Jun 18, 2014)

Hello Rich

You could do something usefull for mankind if You stop trying to make it according to incomplete plans.
If You make it as two stroke with a central exhaust valve actuated by a cam on  crankshaft part number counts is  less
A british mr Wilksch tried to make something like that for small aircrafts and failed as far as I know,mostly due to fixation on making diesel and being three cylinder inline inverted.
A two cylinder two stroke inverted V2 petrol and turboed can do very well up to 300 horsepower were gasturbines take over anyway.


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## creast (Jun 18, 2014)

Thanks peter,
 I can relate to what you are saying and to be honest its much easier in 3D CAD than 2D as you literally build it like its real and can check all the movements and for parts interfering.
 I use SolidWorks in my profession as a design engineer but my machining skills are lacking, but getting a wee bit better as I go. Having got two Stirling engines and my hit and miss engine running I am fairly confident but I do know getting things to run can take a while,, ie weeks or months. LOL!


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## creast (Jun 18, 2014)

Hi Niels,
 Not really quite sure I understand what you are saying.
 Two stroke V twins have to have isolated crankcase partitions to work or a boosted crankcase pressure by some other means, just the same for radials.
 This is a four stroke albeit glow plug and that is what I chose to try. The plans may not be perfect but hey it gives me 90% and the rest will be sorted one way or another. 
 On the subject of inverted engines, I always found these more susceptible to hydraulic lock up if flooding occurs so I would rather go for vertical V.


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## barnesrickw (Jun 18, 2014)

Two stroke V-twin seems to be a popular engine for people to want to try.  I'm guessing it's the love of V-twins and that two strokes seem simpler than four.  For me, the valve train on a four stroke is the intimidating part.  


Sent from my iPad using Model Engines


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## creast (Jun 19, 2014)

barnesrickw said:


> Two stroke V-twin seems to be a popular engine for people to want to try.  I'm guessing it's the love of V-twins and that two strokes seem simpler than four.  For me, the valve train on a four stroke is the intimidating part.
> 
> 
> Sent from my iPad using Model Engines



Yes, 2 strokes are easier but in a V twin? I have not found any plans that cover this in any real way.. maybe you can point me to one?
And yes.. I agree.. valve trains are very intimidating


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## johnny1320 (Jun 19, 2014)

V twin two strokes will only work if you can have separet crankcases for cylinder charging.


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## barnesrickw (Jun 19, 2014)

Somewhere on this forum there is a build of a v-twin two cycle that did run, although I'm not sure for very long.  I think the guy used two Cox .049 cylinders.  Convention says that separate crank cases or a blower are needed to charge the combustion chamber.  I have seen a two stroke v4 that appears to use very close timing on the transfer and exhaust ports.  http://www.aaenperformance.com/v4_racing_engine.asp But I have not seen plans for any such engine.  I think some enterprising home machinist who can cut cams should do so, and sell them.  Then we can just make four strokes.  


Sent from my iPad using Model Engines


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## creast (Jun 24, 2014)

Well, progress has been a bit slow due to work commitments and such. The timing case is coming on slowly but not without a couple of dilemmas.
Firstly I was a little over zealous with the feed on the bridgeport and the part was wrenched from the dividing head. Luckily no real damage was done.
Next was a broken drill in the mounts for the tappet guides so I drilled a further 2 holes each diagonally as only two are in fact used. As it happenes, the drill was push back out when milling the cavity for the cams/gears.


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## creast (Jul 3, 2014)

I have not had much time to progress far with this project but today I had a go at making the cams. In the original article the cams were pretty much hand filed and I really didn't fancy that. I pondered on making a cam grinder but then decided to go the eccentric turning route as per the  Edgar T Westbury method.
My turning fixture was hurriedly made but at least I knew the offset was ok despite hacksawing the clamp details!
This process is very slow, turn a bit and then rotate the cam 5 degrees or so each step. The cam blank pair is Loctited to a temporary shaft and will come off when I finally heat treat them.
All in all it took 1.1/2 hours to turn the two cam part.


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## creast (Jul 10, 2014)

Progress is slow.
I have finished both cams and heat treated them. After making a trial test piece for the gear meshing I machined the timing case centres accordingly but found the gears binding badly. Perhaps the cheap gear was a bad idea as they were obviously not running true. I re-bored and bushed them and even re-bushed the pinion shaft bore. Looking at the teeth under a x20 Lupe I could see the teeth were not that great.
However, I have left it running in my lathe and hopefully the tight spot will ease off otherwise its start again and I have little enough time or patience.. LOL!


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## Swifty (Jul 11, 2014)

Others have used a little lapping paste on the gears to run them in, reports are that it works well.

Paul.


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## creast (Jul 11, 2014)

Thanks Swifty. I will give it a go.


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## petertha (Jul 13, 2014)

creast said:


> .. Perhaps the cheap gear was a bad idea as they were obviously not running true. I re-bored and bushed them



May I ask what sort of commercial gears they were? Reason: I've seen some what I think are RC car type gears down in low tooth count (metric) sizes, but have no idea if they would be suitable or not.


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## creast (Jul 13, 2014)

The gears were purchased from Rapid Electronics, 
http://www.rapidonline.com/FFSearchResults.aspx?query=48dp gear&filterSearchScope=1
 and they are ModelCraft brand. They were the cheapest I could find that would suit at only a few £ each, others would have cost around £40 a set and I thought that a bit steep. I do not have the facilities to cut my own otherwise I probably would have a go. The teeth don't look that smooth under magnification but I think I should have held on the OD originally rather than the boss to bore them out. I did go back that route to correct them but there is still a slight tight spot.


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## SixSixSevenSeven (Jul 13, 2014)

On the subject of 2 strokes from the previous page. I've just been watching a video of a cutaway V-twin, [ame]https://www.youtube.com/watch?v=_-PxRpPgHAM[/ame]
With the 2 pistons sharing 1 crankpin they do move almost simultaneously, now I'm no expert but it does look like on a sub 90 degree V-twin like this at least you could probably use the crankcase to charge the cylinders as is. Of course on a 180/flat then it becomes impossible to use the crankcase and anywhere inbetween will probably just prove damn difficult. But on the arrangement I linked, my belief is that it would be possible.
Of course you do also get setups like the old detroit diesels, fuel/air mix never even touches the crankcase and is supercharged instead, intake port in the cylinder is still in the conventional 2 stroke location, exhaust port is poppet valved from overhead cams (and with 4 valves per cylinder on some models), full pressurised oil system and the full malarkey. Defeats the purpose of 2 strokes being more mechanically simple though.

The Aaen performance v4 may well be 2 2stroke v twins as I describe back to back (and is poppet valve exhaust with fuel injection too)



I'd take anything I say with a pinch of salt though when my workshop consists of a bed and my tool collection consists of a few screwdrivers. Hands on engine experience, does driving a car count? Probably not, don't really touch the engine except to check the oil level and bash the fuses back in after they get shaken loose (seriously, who at opel thought that sticking the fuse box above the front left wheel is a good idea? Hit a speed bump, there goes another fuse, never buying another vauxhall, too many problems).

I just love reading these projects and watching the engines come alive, slowly got a .txt full of notes coming together though for in a decade or so when I finally get around to having the tooling to try myself.
Excellent work, looking forward to seeing the result.


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## creast (Jul 13, 2014)

Hi Six, 
Hope you don't mind me shortening your nick 
Yes it does look feasible for that angle to work, its almost like its one big single really. Nice vid!
As for the Vauxhall, I have one, a Corsa, and its not the only make to put fuses in a stupid place either. Try some of the french varieties, they put them all over the place!
Thanks for the useful info!


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## edholly (Jul 13, 2014)

I know this thread is about the build of a wonderful engine and maybe one shouldn't "but in" - but thought I'd add here that I have built two  ..  60 degree Vee twin 2 strokes and have proved that although it looks like it will work in theory as a big single, fact is that it does not. The lead cylinder gets the lion's share of the crankcase mixture leaving the following cylinder with almost nothing. If you want to follow the build of the last engine see ... http://www.homemodelenginemachinist.com/showthread.php?t=22760&page=6  ... Ed

Probably the most relevent sentence from around 3 months work ...

_As for the Vee Twin itself, in reflection a lot of fun work to get to  the point where I have to class the design as something that won't work  as a simple 2 stroke. I really enjoyed the exercise however and have a  couple of nice motors to look at and occasionally run, but the built in  inefficiencies mean that they struggle to be as powerful as the single  cylinder from which they are derived._


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## johnny1320 (Jul 13, 2014)

Harley is 45deg it might work. For best results you need separate crankcase, outboard motors use a ring on the crankshaft to seal the adjoining cylinders.


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## johnny1320 (Jul 13, 2014)

Edholly built a 60deg diesel two stroke on this forum, he found abandoned the design for a inline twin with better results.


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## creast (Jul 14, 2014)

edholly said:


> I know this thread is about the build of a wonderful engine and maybe one shouldn't "but in" - but thought I'd add here that I have built two .. 60 degree Vee twin 2 strokes and have proved that although it looks like it will work in theory as a big single, fact is that it does not.



Thanks for the 'real data' Ed,
 It did occur to me overnight that the only chance for the 45 degree to work as a 2 stroke is in fact when its working like a big single and as you point out it never really is as there is a phase difference. Anyway, you might as well just make a big single anyway. Thanks for confirming my suspicions and I will get back to making the valves for my 4-stroke 
 Rich


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## creast (Jul 18, 2014)

Today I started on the tappets.
The article called for M.S case hardened but I chose to use silver steel (drill rod) as its an easier process to harden/temper.
The drawing also suggested making one piece which is a bit tricky for my skills in trying to hold tolerance and finish over quite a long flimsy shank so I decided to fabricate.
The followers were made from 01 tool steel and subsequently hardened.
The shafts were ground stock 2.5mm rod and were turned on the ends to 2mm dia to provide location in the holes of the follower, just the tips were hardened to match.
Loctite 603 was used to secure the parts together and then the working face rubbed down on fine abrasive paper until the shaft ends blended into followers.


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## creast (Jul 18, 2014)

Finished tappets


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## creast (Aug 1, 2014)

Little progress to date since I have been away on vacation.
The tappet guides are now machined but I had to do a little bit of 'furtling' as we say here to get the tappets to clear the timing gears so they are now a bit thinner than planned.
The cams cannot be Loctited in position until I have sorted the pistons, cylinders and con rods etc but I have trial fitted the parts and all seems ok so far.


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## johnny1320 (Aug 1, 2014)

Very nice!


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## creast (Aug 5, 2014)

Today I started on the conrods. After milling the rectangular shape and reaming the little ends and for the big end bushes, I decided a fixture was really required for the profile milling.
Not having CNC, I decided to rough the part out in a nibbling fashion first.


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## creast (Aug 5, 2014)

Finally the roughed out ends were radiused by the somewhat 'iffy' method of rotating the part on the fixture by hand around the cutter. Care has to be taken here if you have not attempted this before since the cutter will snatch the part if it is in 'climb milling' direction. So do be careful!!
Final smoothing of the profile will be by hand. Next is to slit the bottoms for lubrication feed.


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## creast (Aug 22, 2014)

Not much progress of late as I have been working on my other project, a CNC router, and I am awaiting delivery of some case hardening compound. I decided to trial fit the parts so far and identified a few parts that need a little adjustment but nothing major.


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## johnny1320 (Aug 22, 2014)

I can't wait to hear it run.


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## creast (Aug 23, 2014)

johnny1320 said:


> I can't wait to hear it run.



Me too!!


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## creast (Sep 5, 2014)

Well, after managing to wreck one of the steel cylinders during my heat treating experiment to just case harden the bore only I decided to go a mre traditional route and re-make the pair from aluminium and propose to shrink the cast iron liner in place. Actually this means the cylinders will be 30% lighter so its no bad thing either.


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## creast (Sep 10, 2014)

Progress is slow but I now have the liners fitted and scalloped out to clear the crank. Unfortunately I overlooked the fact that the aluminium finned sleeve, being now thicker to accomodate the liner, prevents the nuts fitting to the studs. This means I will have machine reliefs at the four stud positions. Oh well!


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## creast (Sep 18, 2014)

After another short break away I have managed to get the pistons machined. The rings have also been turned and rubbed down flat at the expense of abrading away my finger tips! Next step is to split and heat treat them. In the meantime, I can now Loctite the cams in the correct position to the pistons at TDC etc.
The Brass spacer tube where the prop fits is just to allow me to turn the crank more easily and keeps the end float to a few thou.
As I only get fragments of work time on this project I think it may be Christmas by the time I get to finish it! So.. that's my deadline


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## creast (Oct 1, 2014)

The piston rings have now been gapped and heat treated ready for final fitting. I made a few spares just in case of breakages.
I had intended to make the valves two piece using silver steel ground stock and a stainless head but in the end decided to have a go at one piece in free machining stainless 303.
I was pleasantly surpised how well it went, taking cuts down to near size progressively from right to left in 6mm long sections. No centre was used and the final diameter carefully polished to size.
Work is now starting on the heads and so far I have machined the seat face details ready for the top side milling.


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## petertha (Oct 1, 2014)

Coming along very nice! Couple questions:

- the cylinder studs that are resident in your crankcase, are they basically socket set screws or chunks of fasteners/threaded rods? What thread size?

- when you drilled for them, are they right through into the internal chamber but stud elevation set & secured with locktite or similar? (reason I'm wondering is some plans I have that show as blind hole so figured maybe a concern with leakage or something if connected)

-on the head picture re the induction/exhaust port, what diameter is the port & what fastener size to be used on manifold flange 2 bolts? (I like this idea over threading for a big flange nut or similar, especially if its interrupted with fins).

 - looks like valve seat is integral with head itself vs insert seat/guides?


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## creast (Oct 2, 2014)

Hi Peter
The studs are M2.5 and proper studs i.e threaded then plain dia then threaded. Was tedious making them!So they bottom out on the plain diameter. I will use thread locking compound on then final assembly.
Not all are fitted as yet as they need some trimming. The holes go right through to the crankcase since being 4-stroke it doesn't really matter about air leaks (the case has a drain underneath anyway).
The exhaust/inlet ports are 5.5mm diameter close to the imperial size from the plans. I intend to studs here too but they are a bit twee at M2. If I did this engine again I would definitely change some of the features. I tried to avoid B.A threads but in some respects they work better.
The seat is indeed in the alloy head rather than a seperate seat or combined seat/guide. If I mess up maybe I will fit the latter.
Thanks for your interest.

Rich


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## creast (Oct 9, 2014)

Well, I have now pretty much completed both heads and all they need is a bit of fettling to finish. Both have the guides fitted but I am now waiting for a reamer courtesy of Ebay to finish them.
Tonight I have wound the valve springs and have yet to dress the ends square.
I also have the boring task of making many studs to secure the cylinders and heads!


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## petertha (Oct 10, 2014)

Looking good.

 On the piston ring heat setting, did you follow Trimble type formulas for dimensions & gap size etc, or some other method?

 Are any modifications required to a conventional glow plug, or basically just screw it into head as shown?

 What was your valve spring recipe/winding procedure?


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## creast (Oct 10, 2014)

Hi Peter,
For the piston rings I turned them to match the bores and then snap cut with side edge cutters and dressed the break with wet n dry paper. 
I then spragged them open with a piece of scrap and clamped them flat betwen two large washers. The stack was then evenly heated with a blow torch to cherry red and allowed to cool naturally. This method seems to work but as yet I have not installed or run them. I still have to gap the rings to the cylinders.
The glow plug is a 4-stroke type and in fact I posted another query on HMEM to see if the recess was excessive despite being to drawing.
http://www.homemodelenginemachinist.com/showthread.php?t=23607

I used 24swg piano wire to make the springs. After trialling on various rods I settled for a 4mm rod which had a small hole drilled thro to anchor the wire for its first wrap. A tubular guider was placed in the toolpost of the lathe to direct the wire and the leadscrew was set for approx 2mm pitch. Turning the lathe by hand and maintaining tension, several close wound wraps were made before engaging the leadscrew. After sufficient turns, the leadscrew was disengaged and more close wraps added. The springs are then trimmed back to remove the excess coils and flat faced each end on a diamond disc. I did bake these at 130 deg C for an hour to stress relieve but I have since seen this should have been higher around 200 deg C.
They are not perfect but I think they will be fine.


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## creast (Oct 18, 2014)

The heads are now pretty much complete and another trial assembly to check the rockers and valves. The springs feel pretty firm, more than I expected but they are close to the plans dimensions. My guess is they are about 1 to 1.5 lbf compressed. Next is the push rods and then the tricky fabrication of an inlet manifold as I have chosen to try it out first on a single carburettor from an R/C supplier.


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## Syd (Oct 18, 2014)

Hi Creast. Looks to be a nice bit of machining, isn't it tiny! I'm intrigued by the overhung crank, how did you attach the camshaft? Looking forward to your next post.
Cheers, Syd.


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## GailInNM (Oct 18, 2014)

That is a great looking engine.  Very nicely executed.
Thm:Thm:
Gail in NM


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## creast (Oct 18, 2014)

Thanks for the kind comments Gail & Syd.
Syd, the cams are gear driven by a rotary arm which is driven by the crank pin. Some of my earlier posts show the timing case. I have attached section view from the plans which may explain better.


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## creast (Oct 23, 2014)

Tonight was spent lapping in the rings. I hadn't intended to but the plans say otherwise. Anyway the engine was feeling tight and although slightly less, still is.
The push rods are done and its getting close to try running. I am still struggling with the inlet manifold for the single carb which I feel is a quicker route to running but maybe I am wrong.
I just had to try the prop on to see how it looked and also make turning the engine over easier!


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## James6605 (Dec 28, 2014)

Beautiful work mate!! Can't wait for the video of the maiden run.


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## necchiom (Dec 28, 2014)

Awesome! With compliment. When the first run?


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## petertha (Dec 28, 2014)

creast said:


> Tonight was spent lapping in the rings. I hadn't intended to but the plans say otherwise.



Looking good! Care to elaborate on your liner & lapping procedure? (I'm info gathering on my cylinder trial/mockup).

 - did you use a lapping tool & compound to dimension & condition the liner ID's?
 - anything subsequent conditioning like those balled abrasive brush hones to give the criss-cross pattern?
 - by 'lapping in the rings', do you mean rotating engine under low external power or..?
 - I'm interested in the fit & machining of aluminum cylinder & sleeve. Is it a heat shrink fit, or sliding fit? Are the jugs just bored or also lapped?


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## creast (Dec 29, 2014)

Well it has been some time since I posted. I had hoped to have completed this project by Christmas but alas not so.
I have been struggling to get any life out of the beast and my first suspicion was the compression. I have resorted to just trying to get one cylinder to run first and this has lead to me making a new piston with a tighter fit and virtually no ring gap. I have also just gone for one ring rather than the two rings in a single groove.
The cold weather does not help and with a bit of pre-heating the cylinder with a blow torch she did try to run a few times and then compression was down again.
It appears the inlet valve is not seating properly and despite re-lapping the seat I am still stuck with a pretty ornament.
I decided to leave it a couple of weeks and regain my composure over the seasonal break 
My task now is to modify or make new the head to ensure seating is correct.
Peter,
The lapping was simply done with very fine metal polish with the rings on the piston and moved in and out the cylinder whilst rotating in the lathe. This was done until the ring showed uniform polishing around its periphery. Not sure this is the best way really, I am still learning myself. No other laps or hones were used.
The cylinder was bored approx 0.0015" undersize of the liner diameter and heated in an oven to 200 deg C before pressing the liner in which in fact pretty well fell in. My first try was to do it by hand but as soon as the liner touched the bore it chilled the cylinder enough to grab it so always use a press of some sort or be very sure and quick!
Not sure what you mean by 'jugs' ?


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## petertha (Dec 29, 2014)

Good detail thanks. I know what you mean about the steel liner > aluminum cylinder near instant heat loss. Funny, I've rebuilt my RC engines a million times & never paid much attention until just recently. The external liner finish is actually very smooth & same goes for ID of aluminum crankcase. Looks like lapping type finish, even on the aluminum ID. I think this combination likely assists easy liner insertion & removal because any machining roughness is only going to be more 'grabby' going in & out. I put my crankcase in a 400-450 degF toaster oven. The liner rarely has much resistance, this is more for the bearing removal. It would be kind of a shame to sacrifice the aluminum cylinder with a permanent liner, hence the question.

'jugs' = vernacular for 'cylinders'. Maybe its a N-Am thing. 
http://www.totalmotorcycle.com/dictionary/J.htm
There's another kind of jugs, but I wont go there!


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## creast (Jan 4, 2015)

As I mentioned previously, I am concentrating on getting at least one cylinder running and I have to thank messrs Britnell, Mayhugh and Rupnow for their previous threads elsewhere regarding valve seating which has given me more insight into getting these things running. My Vega is definitely suffering from seating problems. Compression is there and then it isn't. I have boosted the spring force by shimming the springs but it hasn't solved the problem. I am also getting blow back through the carb, sometimes badly.
I intend to move away from the seating in the alloy head and go for a bronze seat guide arrangement which means considerable re-work but I feel I have to get this better.
One encouraging thing is I do know it is capable of running as per the YouTube link, albeit several short runs of around a minute at best. 

[ame]https://www.youtube.com/watch?v=n1SHT9w39xc[/ame]


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## creast (Jan 27, 2015)

Well, I thought I was making progress but over the last week or so I have got very close to chucking the towel in. This engine is just is so fickle to get trying to run.
My original heads didn't seem to seal well on the valves and after making some tweaks I managed to wreck one of the heads so made two new ones which had lower volumes since I suspected compression was an issue.Valves seem to seat good in the aluminium.
Just working on one cylinder to run is a challenge and I wonder if I should have picked an easier project first. I have never made a glow engine before never mind a 4 stroke twin!
I have tried a commercial carb to rule out my own but in fact the Vega carb does just as good so that rules that out. I have tried various glow plugs and now on OSF type as they claim to be best for 4 stroke plug.
Fuel is 5%Nitro castor base.
The only way I can get life out of it for short runs of about 30 secs or so is by heating the cylinder with my micro blow torch to get the cylinders warm.
I have altered compression by using a gasket and that does not make any difference.. it will still run after heating on the lower compression.
I thought the cold weather may be the cause but |I remember as a teen running cox baby bees in winter? Today was 6deg C so not too cold.
Does anybody know what might be at fault?

Yours desperately,
Rich


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## canadianhorsepower (Jan 27, 2015)

Hi Rich
Here are my sugestion   :hDe:
#1 I would make a small hole anywere in the crankcase (that could be plug latter)
#2 I would build a small plug attachement to replace the glow but allows you to bring the pressure in the cylinder
 with both valve close to about 15 lbs to check for any leaks. (the hole in the crank case would indicate piston rings leaking.
#3 when all of the leaks are fixe I would do a  mecanical compression test. ( the chamber looks pretty big)
and it will determine your valve timing is good or not.

#4 send it to me Id love to have it as a trophy Rof}Rof}Rof}
good luck


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## petertha (Jan 27, 2015)

creast said:


> The only way I can get life out of it for short runs of about 30 secs or so is by heating the cylinder with my micro blow torch to get the cylinders warm. Rich


 
Rich can you elaborate. You mean if the engine is cold it wont start/run well at all period? But if pre-you warm the cylinder barrels you get a run but only 30 seconds, or it keeps running thereafter? Sounds like you are doing all the right things, so keep eliminating variables one by one.

Are you keeping power on the glowplug during running? What happens if you pull the power off?

The heat has me mystified depending on your answer. Maybe its affecting compression by the piston/liner fit? Remind me once again, what's the materials configuration? 

How about the rocker/valve gap? I've seen a tiny amount descrepancy cause havoc with I/E timing, especially if it floats or similarly effected by heat.


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## creast (Jan 28, 2015)

canadianhorsepower said:


> Hi Rich
> Here are my sugestion :hDe:
> #1 I would make a small hole anywere in the crankcase (that could be plug latter)
> #2 I would build a small plug attachement to replace the glow but allows you to bring the pressure in the cylinder
> ...


 
Luc,
Thanks for the input.
The crankcase has a drain hole already and one point is that the bottom end relies on blow by for lubrication (as per design plans) so the ring/rings must leak a bit anyway.
I confess to changing to a single ring but compression does seem fair, but its hard to tell what's right when you have never built one before.
The air test will be good to check the valves so I will make an adaptor.
Sorry but it will stay as an ornament here if it never runs  (cheeky Rof})


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## creast (Jan 28, 2015)

petertha said:


> Rich can you elaborate. You mean if the engine is cold it wont start/run well at all period? But if pre-you warm the cylinder barrels you get a run but only 30 seconds, or it keeps running thereafter? Sounds like you are doing all the right things, so keep eliminating variables one by one.
> 
> Are you keeping power on the glowplug during running? What happens if you pull the power off?
> 
> ...


 
Hi peter,
If the engine is cold then it will do the odd sputter but not enough to run proper. Warming seems to encourage it to fire and once running I try to tweak the mixture which it does respond to but often dies after say 30 seconds. It needs plenty of priming to run and this is often borderline of locking up so I have to be careful.
When running I have found putting the tank level higher than the carb helps but then is prone to flooding when it stops.
I can't help but think a fuel feed issue is part of it.
I need to work on the carb since the mixture screw is too loose and I have to hold it whilst running or it unscrews (not making life easy am I?)
Power is left on the plug and by the time I get to unclip it the engine has stopped anyway.
I think warming is probably helping the fuel to vapourise and making it easier to ignite, but thats just a hunch.
Valve clearances are around 0.002" and I have fiddled with these to see if it changes the character.
Thanks for your input
Rich


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## James6605 (Jan 28, 2015)

Rich 
Fantastic effort on the engine mate! Well done.

That problem you mention with the mixture screw unscrewing itself rings my alarm bells.
If the screw does not seal properly in the carb spraybar thread, you are losing the vacuum signal generated by the airflow that will draw your fuel into the airstream.
Try slipping a piece of rubber tubing over the needle and spraybar where they screw together to seal it.
This concern is confirmed by the fact that raising the tank helps.

All the best
James


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## petertha (Jan 28, 2015)

I experienced kind of the opposite issue where a (worn out) 4S starts up ok when cool, but fades away & dies after warming up or any kind of load. You then find yourself mixture control tail chasing because one setting cant satisfy transition between 2 very different running conditions.

So your pre-heat thing has me wondering... I've never done this on RC-4S & so not even sure what to expect. 
http://www.dynamiterc.com/Products/Default.aspx?ProdID=DYN2514
But do you think you could rig up something like this, apply it to your non-running cylinder, then switch cylinders, then with/without pre-heat. Its almost like the heat is affecting your overall compression, but I'm having difficulty visualizing how (typical ringed aluminum piston in steel liner in aluminum sleeve)? Usually a good running RC engine has a nice compression pop-over bounce over TDC, but that's a feel thing, not really a number. I'm not sure if this gauge preserves the net high pressure on the needle or if it would just bounce around & tell you nothing.

One of those el-cheapo temp gauges might help quantify heat. ie what is pre-heat vs running heat vs (maybe friction induced heat)?
http://www.amazon.com/dp/B00144E8A4/?tag=skimlinks_replacement-20

The elevated fuel tank is essentially making it richer fuel/air ratio all things being equal. But richer on these fiddly things can also have other tangent offshoots with pre-mix oil glow fuel like head temp & to lesser degree compression. But yes, you need the carb needle valve / mixture nailed down first, otherwise everything is out of whack.


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## petertha (Jan 28, 2015)

Another thought (because the Vega carb & induction pipe is a bit different than typical RC) - do you have good seal between carb body & manifold stack interface & stack / cylinder port? Typically a combination of soft durometer o-ring & gasket paper is employed. This can be another temperature induced variable with differential expansion. I've seen cases where the smallest micro-gaps cause grief. You can jerry-rig test with some gasket silicone spooged around the joint as long as the metal is cleaned with brake fluid.


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## creast (Jan 28, 2015)

James6605 said:


> Rich
> Fantastic effort on the engine mate! Well done.
> 
> That problem you mention with the mixture screw unscrewing itself rings my alarm bells.
> ...



Thanks James, that's a very useful tip. In fact I had seen similar on a second hand engine I bought and thought it just to stop unscrewing but your comment on air leaks makes sense.
Cheers
Rich


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## creast (Jan 28, 2015)

petertha said:


> Another thought (because the Vega carb & induction pipe is a bit different than typical RC) - do you have good seal between carb body & manifold stack interface & stack / cylinder port? Typically a combination of soft durometer o-ring & gasket paper is employed. This can be another temperature induced variable with differential expansion. I've seen cases where the smallest micro-gaps cause grief. You can jerry-rig test with some gasket silicone spooged around the joint as long as the metal is cleaned with brake fluid.



Thanks for all your comments Peter.
I am sceptical about the pressure gauge only in how much volume is in the gauge itself could influence the compression reading. A very small strain gauge transducer would ensure minimal extra volume but a lot more complexity.
I take note of your comments and as agreed, the carb needs sorting first. I will also double check the valve timing but I don't really think this the issue. 
Yes, the carb track is long and tortuous and I did ponder on trying a carb directly onto the head to see if that works better.
So many things to check! I have stripped this thing down so many times I must confess to losing enthusiasm but when it fires up I get back up. But for how long  LOL.
Cheers
Rich


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## creast (Jan 28, 2015)

petertha said:


> I experienced kind of the opposite issue where a (worn out) 4S starts up ok when cool, but fades away & dies after warming up or any kind of load. You then find yourself mixture control tail chasing because one setting cant satisfy transition between 2 very different running conditions.
> 
> So your pre-heat thing has me wondering... I've never done this on RC-4S & so not even sure what to expect.
> http://www.dynamiterc.com/Products/Default.aspx?ProdID=DYN2514
> ...



Peter,
I just found this simple but possible tester by Jan Ridders.
http://modelengineeringwebsite.com/Compression_tester.html
At least it doesn't introduce much additional volume.
Rich


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## Syd (Jan 29, 2015)

Hi Rich. I hesitate to offer advice on small engines when I've never built one in my life, whilst turning skills are such that I live for the day when I'll successfully part off a workpiece without snapping the tool! A Mill? dream on!
However, as part of a misspent youth, I devoted much time and effort on single cylinder motorcycle engines, both for a one kick start and then getting away quicker than the other chaps on the start line.
When you're staring at an uncooperative lump of machinery that won't do what Herr Otto says it should, it's worth going right back to basics:
You absolutely must have a flammable mixture of fuel & air. 
Air is sucked into a cylinder by way of a valve, opened to create a partial vacuum created by a downward moving piston. This valve closes around bdc. and the vapour is compressed by the now rising piston and at tdc, a spark ignites the fuel vapour, expansion of which causes the piston to travel down again.
Around bdc a further valve opens and the gas is forced out of the cylinder by the rising piston.
It is very, very easy not to have both valves firmly seated and sealed throughout the compression stroke (and most of expansion stroke of course. Guessing that there will little, if any, valve overlap.)
Air leaks, must be eliminated, the only air entering the inlet manifold, must come from the carburettor inlet. (your loose screw?)
Fuel must be drawn from the jet into the carb. by air passing over it, not by spilling over, otherwise it will not atomise sufficiently. (fuel level at the jet should be same as in the tank, unless the carb. has a float chamber.)
The smaller the engine, the more important good compression, so very small piston and ring clearances.
A reasonable compression ratio (perhaps of around 7-10 ?)
A good spark at the right time. (On my engines it could be anything from 3 to 9mm. before idc, but this was with an 88 - 90mm stroke.)
Hope something here might prove useful, but I thoroughly enjoy all the threads and fascinated by the quality of workmanship. 
Cheers, Syd.


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## canadianhorsepower (Feb 9, 2015)

any good news on your vega
 cheers


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## creast (Feb 10, 2015)

canadianhorsepower said:


> any good news on your vega
> cheers



Hi Luc,
I only just managed to get some time on the engine this week.
I made the Ridder compression tester to compare to other engines I have and the R H cylinder was higher than a rather worn Enya 19 which runs so I thought maybe my compression was too high?
After checking against another engine which gave equally good compression I ruled that theory out and simply tried to run her again. Guess what? She ran for minutes at a time. The only thing different was the ambient temperature, its a good 5 degrees warmer than previously.
I tried the other cylinder tonight and that ran without warming but died after a few minutes and compression was gone. I removed the head and fitted a blank one which is showing its rings/piston.. probably worn out whilst testing the other one! :wall:
So, tomorrow is 'make a new piston/ring combo time' to match the other one which is still feeling good.
Am keeping my runs running rich for now to ease it in.
Cheers,
Rich

http://youtu.be/Xzf2S02-kfk


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## canadianhorsepower (Feb 10, 2015)

well thats good news Thm:Thm:
thanks for posting


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## creast (Feb 10, 2015)

I could do with someone else making one to put me right 
All the others that have built this beast either never completed it or do not respond to my pleas for guidance, pioneering stuff eh?


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## canadianhorsepower (Feb 10, 2015)

creast said:


> I could do with someone else making one to put me right
> All the others that have built this beast either never completed it or do not respond to my pleas for guidance, pioneering stuff eh?


 

well well well Thats all I needed:fan:
I'm still waiting on some material to build Brian's engine:wall:
I'll give that one a shot. I have all the material here

so Its a go:hDe:


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## petertha (Feb 10, 2015)

creast said:


> ..simply tried to run her again. Guess what? She ran for minutes at a time. The only thing different was the ambient temperature..


 
That's great news! The other thing I forgot to mention in my 99 ways to cuss at RC engines is old, skunky fuel. Methanol attracts moisture which can be an issue in humid, cool climate even over a single winter storage & maybe further hampered by lights ends vaporizing off. Particularly if the lid is not air tight or a half filled container. Sounds like you are on the right track now, but that's another trick to try. I would also give it a tank test of higher nitro content just to see. Maybe you can find a small qty at hobby shop. If it starts & idles better as is often the case, its a simple fix & cant really hurt anything unless you go to too high for plug/CR(like +30%).


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## creast (Feb 11, 2015)

Thanks Peter,
I have pondered that but I have been working on the 'if the other engines run on it then it should be fine' basis, however the other engines are 2-strokes so probably sustain running easier.
I have also been playing around with various glow plugs but settled on an OS F type for now.
Cheers
Rich


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## creast (Mar 29, 2015)

Its been a while since my last post and I have to admit to being very close to chucking in the towel, I abandoned the project for a month as I was close to throwing it in the bin.
However, the rest did me good and I have learnt a few things about engine construction over the last few weeks.
I had always suspected the compression wasn't good enough and after chatting to a colleague who races two stroke motorcycles I decided to follow his advice and remake the pistons and rings. I went a stage further and made the pistons with two separate ring grooves as opposed to the plans two rings in one groove.
This meant making the pistons 1 mm longer to accommodate the second groove and hence a spacer was required to prevent the piston hitting the head.
The piston was made a closer fit, half thou under the bore diameter. The rings were made size to the bore and lapped in an identical bore to the cylinder.
I had discovered that as perfect as the ring may be, when spragged to give the gap it does not form a true circular contact when fitted. I think this was the crucial thing affecting compression and was born out by the results of the new method as I now had decent compression and a good bounce on the propeller.
Individually both cylinders now run fine on their own and starting is much much easier. However, put together I cannot get any life out of it and suspect I am not going to be able to hand flick start this beast. There may also be insufficient inertia in the prop so I will try a larger item.
Interestingly, the engine is very sensitive to the glow plug type. OSF 4 stroke plugs are a bit borderline and the engine really starts well on an Idle bar plug 'Taylor Made' brand so I will probably stick with those.
Hopefully I will get this twin running soon!!


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## petertha (Mar 31, 2015)

I admire your tenacity & trust it will ultimately pay off. I'm making my 'prototype' cylinder tower now. The plan is to chicken out & use a commercial ring to confine potential problems to the other 101 things that will likely go sideways. 

One thing I wanted to ask. In Terry's 18C radial build, he shows his flashlight method, shining up through the bottom of the sleeve. The idea is any eccentric gap between ring & bore allows light to peek through. I bought a new OS-56 piston/liner/ring combo to reference/replicate the dimensions on my build & just about to perform this test to see what a new 'factory' engine looks like. Hopefully I can take a pic & post. Did you ever try this trick during your ring iterations?

Also, maybe you mentioned already, what were your target dimensions:
- piston groove width (ex 0.001" wider than axial ring thickness)
- piston groove depth (ex 0.005" deeper than compressed ring ID)
- piston OD reduction relative to bore


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## creast (Mar 31, 2015)

Hi Peter,

No I didn't try the torch trick but I did hold it up to a light but couldn't see any gaps. The main indicator was the uneven polishing of the ring when it was dismantled after hours of flicking which lead me to believe something better had to be done.
Careful lapping in an identical bore did the trick.
I have tried several different ways to make the rings including temperature contolled kiln with fixtures and simple blowtorch method.
To be honest, my successful rings have simply been spragged onto a 2.5mm thick bar and just a quick heat to dull red with a blow torch. No clamping has been used and the four rings came out great. The kiln ones @ 10 minutes actually came out more brittle.
The main problem with spragging for heat treat is that the highest stress is opposite the gap and this inevitably means its here the greatest stress relieving occurs so curvature changes more at this point than the sections near the gap so there is no way you will get uniform pressure when its compressed in the bore.
For the record, my piston is 0.0006" under bore size (0.0003" radial).I know that sounds really tight but 50cc racing two strokes run close as this and so far it hasn't seized. If it does I will post on here 
Ring thickness is around 0.002" under groove width and the groove depth is 0.003" more than the ring radial thickness.
The piston was made size to bore and did need a little dressing of the break ends with wet and dry abrasive to get it to enter the bore before final lapping/polishing.
I can also recommend the Nemmett method of breaking the ring by pushing it down carefully on a morse taper until it cracks at the weakest point.
I have also learned my lesson and now fit and remove the rings using shim stock strips, its more reliable than not doing so.


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## petertha (Mar 31, 2015)

creast said:


> For the record, my piston is 0.0006" under bore size (0.0003" radial).I know that sounds really tight but 50cc racing two strokes run close as this and so far it hasn't seized.


 
Thanks for all the parameters. Sheesh, everything looks to the book. Now I'm really worried when I have to cross that bridge.

Re the piston, this topic came up in another post. I can't recall your bore size, but can you check my sample math. One would thing getting pretty tight, but maybe some parameters are off?

1.23 E-5 in/in/deg F= thermal coeff aluminum
0.5" = piston dia
 250 deg F = running temp (assumes nil liner expansion)
= 0.0015" = thermal expansion
0.0006" = clearance at ambient
=<0.0009"> = interference!


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## creast (Mar 31, 2015)

Yes I was worried too... LOL
Fact is, I have just ran the tighter of the two cylinders at 6000 rpm for 10 minutes continuous and no problems. I will check the figures and for the cylinder liner too. I have to admit I did worry about the expansion but thought hey.. what the heck... if it runs I am happy even if short lived.. but that's not what has happened so far!



petertha said:


> Thanks for all the parameters. Sheesh, everything looks to the book. Now I'm really worried when I have to cross that bridge.
> 
> Re the piston, this topic came up in another post. I can't recall your bore size, but can you check my sample math. One would thing getting pretty tight, but maybe some parameters are off?
> 
> ...


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## creast (Apr 1, 2015)

Peter,
I am pretty much in agreement with the figures you posted even though you didn't state the value of coefficient of expansion used. I got around 0.001" for 120 deg C differential (250F).
My bore is actually 19mm and calculating for 100 deg C differential and including liner expansion I would get 0.0003" interference.
Now there are two things that could explain why the piston isn't seizing.
Firstly, perhaps the piston has worn slightly? I can check this when I disassemble the engine agin.
Secondly, I have no clue what the actual temperature is. The propeller is certainly force cooling the engine.
I could put a thermocouple somewhere but that won't tell me what the piston is seeing. Maybe I could borrow a thermal imaging camera from work to give a better picture of whats happening.
Or maybe bond a thermal indicator strip inside the piston?


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## petertha (Apr 1, 2015)

creast said:


> even though you didn't state the value of coefficient of expansion used.


Its this ---> 1.23 E-5 in/in/deg F= thermal coeff aluminum



creast said:


> Secondly, I have no clue what the actual temperature is. The propeller is certainly force cooling the engine...


 
That's the part I'm not sure of either. I've seen reference in the 200F range, but not sure where that came from. The piston crown is right adjacent to combustion front which is very much hotter. But that's only brief time duration, then extended cycles of exhaust & intake, so what's the average? I've always wanted to try & mark the inside of piston ceiling with some sort of temp crayon, but not sure if that would work.


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## digiex-chris (Apr 1, 2015)

hmm. I'm tempted to put a thermocouple port into my engine's head to measure combustion chamber temp directly. Wouldn't be able to measure piston temp though.

200F is a common RC two stroke methanol fueled engine head temp, measured externally to the engine, often with an IR thermometer off of the fins.


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## creast (Apr 1, 2015)

Since this is a four stroke engine I guess it also has more time to dissipate the heat.
I am a bit reluctant to mess with my heads after making them twice 

Back on the piston clearance theme, my friends Yamaha 50cc racer 2 stroke has a 40mm piston and clearance is only 0.0015" total. I know commercial pistons are high silicon and the expansion is approx 18% lower than the alloy I am using (6082) but in proportion that's really a close fit.
And its air cooled too.. no propeller cooling here! 

Maybe I should just accept it works and stop worrying about the expansion?
That's what my mate suggested.. otherwise it could become an obsession.




digiex-chris said:


> hmm. I'm tempted to put a thermocouple port into my engine's head to measure combustion chamber temp directly. Wouldn't be able to measure piston temp though.
> 
> 200F is a common RC two stroke methanol fueled engine head temp, measured externally to the engine, often with an IR thermometer off of the fins.


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## xpylonracer (Apr 1, 2015)

You may find HE15 better for your piston material, available from CES in UK.
Emgee


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## petertha (Apr 1, 2015)

creast said:


> Maybe I should just accept it works and stop worrying about the expansion?


 
Works for me! 
BTW, I measured the OS-56 piston/liner FWIW. 
0.9451" = liner bore dia (4mm nominal)
0.9389" = piston crown dia (reduced to ease ring installation)
0.9421" = piston dia immediately under ring
0.9423" = piston dia at skirt base

So notwithstanding the crown reduction, the main piston blank is 0.003" smaller than bore, or 99.68% of bore, or 0.0015" annular gap. What aluminum alloy piston is made of I can't say. The liner is chromed & slightly hatched, typical RC stuff I suspect.


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## digiex-chris (Apr 1, 2015)

I think the crown reduction might be primarily to allow gasses behind the ring a little easier to push the ring out against the cylinder wall. I've heard that theory in a few model engine design discussions and it certainly happens on some full scale engines that have multiple rings, and therefore no advantage on ring installation.

Here I go on off topic theorizing again. Sorry.


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## creast (Apr 2, 2015)

Thanks Guys,
This is all useful stuff Thm:


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## petertha (Apr 2, 2015)

digiex-chris said:


> I think the crown reduction might be primarily to allow gasses behind the ring a little easier to push the ring out against the cylinder wall..


 
I've heard that too, but I don't quite get it. In order for combustion gas pressure to act on the ring radially outward, seems to me it has 3 distinct connected paths or chamber components:
a- down (gap between piston OD wall & liner ID)
b- over (gap between top of ring & top of piston ring groove)
c- down (gap between ring ID & depth of piston groove)

I would have thought a couple of thou open aperture in these connected pathways to a low viscosity fluid (expansion gas) is equivalent to the patio door wide open. ie. it would see this pressure response right away, so 'opening it up' wouldn't do a lot of good especially over such short distances. OTOH, its probably more complicated than that. Maybe they are liquid (lub oil) filled & that changes the gas only assumption.

I do know playing around with that Trimble calculation that it doesn't take much over-expanding of the ring beyond the (heat set) pin diameter before yield is reached & permanent deformation or fracture. That's what made me think maybe its just a safer way of keeping rings intact if the crown reduction doesn't adversely affect performance.

Good discussion!


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## digiex-chris (Apr 2, 2015)

petertha said:


> I've heard that too, but I don't quite get it. In order for combustion gas pressure to act on the ring radially outward, seems to me it has 3 distinct connected paths or chamber components:
> a- down (gap between piston OD wall & liner ID)
> b- over (gap between top of ring & top of piston ring groove)
> c- down (gap between ring ID & depth of piston groove)
> ...



Given that these model engines are often worked on by people with less interest in model engineering than model engineers, I'm betting it's a little of both.

I'm thinking that spring tension helps bias the relatively equal gas pressure such that it'll tend to close the gap with the cylinder wall and open the gap with the groove minor diameter. Plus the down force closes the gap between the bottom of the ring and the bottom of the groove. I think o-rings tend to seal the same way, being shoved into the crack by pressure. I'll have to look that up again at a later time, I can't remember where I found that.

Tough to test effectiveness at the scale we're using, and so it probably doesn't matter at all.


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## creast (Apr 16, 2015)

After all this time I am now happy to say the Vega runs on both cylinders. There is still more to do to finish this beast but I am relieved the gal runs.
Crucial thing is it does need an electric starter, I had hoped to flick start but there is no way as a twin you would stand a chance. As individual cylinders no problem.
I was also fooled by my power supply not delivering enough current for two glow plugs so that did not help. Can you believe I have got through 1/2 gal of fuel over the last 3 months of trying to get it to run?
Anyway, I am glad I didn't quit even though I was close to many a time.
Its been a good learning curve.
If anyone decides to build this engine I am happy to help with advice despite the lack of support I had from all the other Vega builders I contacted.
I am off on vacation now but hope to post a video completion soon.


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## petertha (Apr 16, 2015)

Awesome to hear & look forward to the vid! When you get settled back in, I'd like to learn more details of your PS current levels; what you were drawing when it wasn't firing so good vs. 'the fix'.


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## creast (May 26, 2015)

Finally!!! I have now finished the Vega and consigned it to the finished projects section of this site. There are some parts which I should have paid more attention to but hey I am not exhibiting this project at a model exhibition and and it was something I wanted to do and yes it almost beat me. 
Overall, I am quite pleased. I have learned a lot from this torment. :wall:


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## digiex-chris (May 26, 2015)

Very nice!


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