# Open Column Twin



## cfellows

I thought I'd move this thread over here where probably ought to be.

Done with the major machining of the heads and have them bolted on to the cylinders now.

This is the view from the spark plug and intake manifold side:






Here you can see where the intake and exhaust valve guides will fit.  You can also see the 3, recessed socket head cap screws that hold each head on:





This view is taken from the push rode side and shows the exhaust ports:


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## wareagle

This one is looking great.  Keep the pictures coming!


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## deere_x475guy

Cfellows this sure is a nice looking engine.  Is this one you designed?  It looks like the crank was machined instead of built up.  Do you build most of your cranks this way?  Nice job and keep the pictures coming.


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## cfellows

deere_x475guy said:
			
		

> Cfellows this sure is a nice looking engine.  Is this one you designed?  It looks like the crank was machined instead of built up.  Do you build most of your cranks this way?  Nice job and keep the pictures coming.



My engine is based on a 6 cylinder model designed and built by Randall Cox.  He has displayed his engine at several of the most recent GEARS shows in Portland.  I saw it when I was there in  2006.  Plans for the 6 cylinder model are also featured in one of the first issues of Model Engine Builder, which the following picture is scanned from.  Everything on my engine is pretty close to Randall's design except I machined the crankshaft from solid and I reversed one of the heads to make the exhaust, intake, etc., symmetrical.  I made the Crank Throws 180 degrees apart so it will (hopefully) sound like an old, 2 cylinder John Deere.






Chuck


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## cfellows

Finished a few more pieces in the past couple of days.  

I decided to make the pistons out of cast iron.  Mostly because I had some the right size and didn't have any 1" aluminum.  Since I intend for it to be a slow runner, I thought the Cast Iron might be more in keeping with the older, slow running engines.

I have to say, I really don't like making Connecting Rods.  They are just so tedius!  And, I've yet to make one that I really thought turned out nice.  Guess it must be time to design a jig to simplify the who process.






Chuck


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## wareagle

Chuck, I for one think the rods look nice.  You did a great job one them.

The pistons came out very well, also.  When you get this engine compete, it will be one impressive model, no doubt about it.  Your getting closer!

Keep the pictures and updates coming!


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## cfellows

Here you can see I've started cutting the large timing gear.  This is a 24 pitch, 54 tooth.  I'm making the timing gears kind of big cause I like to be able to seem them when the engine is running!

Turns out I didn't have the right cutter for 27 teeth for the small timing gear, so I had to order it from MSC.  Darn those things are pricey!  I actually ordered 3 different sizes that I was missing, so now I have darn near a full set for 24 pitch gear cutters.  I'm still lacking the 55-134 cutter.  I expect that will be the next one I need!  I figure I better stock up on tooling before I retire and don't have any money.

This gear is being cut from another piece from the extra-parts bin.  You can probably tell from the photo that I had started to make a 6 spoked wheel sometime in my distant past and decided the spoke was too thin, based on the two holes drilled close together.  I'm probably going to make this gear six spoked as well, but the holes already drilled will be in the waste part cut out between the spokes.






Chuck


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## Bogstandard

Hi Chuck,
Looking good.
I know what you mean about gear cutters, I refurbished an old Myford ML2 a few years back and had to buy some cutters for making change wheels and a new bull gear. I nearly fell off my chair when I was pricing them up.
When I fully retool, hopefully fairly soon, I hope to go for gear hobs, I think they will work out much cheaper, one size does all. Definitely a thing I will have to look into.
I do like the way you have stripped the two cylinders off a six cylinder engine. Are you going to be making the cam out of the solid, or are you going to be building it up? If you get stuck, I have some fairly easy plans for a cam grinder. I have got all the bits to make one, but like most things like that, they are sitting under the bench waiting for the right project to come along where it will be needed, then maybe it will get built. 

John


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## cfellows

Here's the finished gear.  It always gets tense when you get close to the end.  It's easy for the mind to drift when you have such a repetitive task and near the end, you wonder if you miscounted or something.  It's always a relief when that last cut goes in and the teeth are all even!






Chuck


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## Bogstandard

Lovely bit of work.

John


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## cfellows

Bogstandard said:
			
		

> Lovely bit of work.
> 
> John



Thanks, John.  To your earlier question, I am going to build up the cam using the same method that Randall Cox use on his 6 cylinder design.  The intake and exhaust lobes for each cylinder is a one-piece affair with a hub in the middle for attaching to the shaft with a setscrew.  Here's a picture of his drawing:






By the way, what are you doing up this time of night (morning)  Isn't it like 3am over there?

Chuck


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## Bogstandard

Thanks for showing that Chuck, it does make life a lot easier when built like that.
Time now 4.45am, long story.
Nearly time to take hound out for a walk.

John


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## cfellows

Didn't get too much done this weekend. I finished up the pistons Friday night. Today, made the tapered, split bushings to hold the flywheels on and tapered the bore on the flywheels to match. First time I've ever used this mechanism to hold flywheels on. It's not as hard as it looks. The included angle is 8 degrees, as recommended by Roy Rice. I set the compound as close to 4 degrees as I could from the scale. The angle doesn't have to be precise, as long as you taper the bushing and the flywheel bore without changing the compound angle. You also have to be sure your cutting tool is dead nuts on center height for both the bushing and the flywheel tapers or they won't match.






Chuck


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## DICKEYBIRD

Hi Chuck,

Great work sir! I'm interested in the collet style mounting system you're using. That looks like a great way to reduce the runout I always seem to get with flywheels.

I'm familar with the collet/drive washer setup used on many model aircraft engines but with my newbieness, I can't quite grasp what's going on with the system you've used. Got any drawings?

Thanks!
Milton


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## cfellows

Here's a drawing of the tapered bushing assembly. The tapered bushing is turned to a sliding fit over the shaft, then split completely through on one side only. The bushing is inserted into the flywheel hub, then the assembly is slide onto the shaft, flange side out. Screws, inserted through the flange of the bushing are threaded into the hub of the flywhee. As the screws are tightened, the bushing is pulled into the flywheel hub, which is taper bored to match the bushing.  Further tightening of the screws causes the bushing to be squeezed onto the shaft providing a very secure connection.

With the 8 degree included angle, the just loosening the screws will not free the flywheel from the shaft. A screwdriver, chisel or other bladed instrument will have to be (lightly) driven between the flange and the flywheel to pry it loose. A steeper angle would be easier to free up, but also requires a larger diameter flywheel hub.


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## Bogstandard

I don't want to interfere with your explanation of the tapered flywheel setup, but normally what you would do is put two extra threaded holes in the tapered bushing flange. This would allow you to 'jack' the bits apart rather trying to pry them apart. This is standard practice on full sized tapered fittings.
This is a very good setup for flywheel mounting, I used it on almost all my ic. engines.

John


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## dparker

Chuck: When I was working with belt driven pumps we used split taper hubs on the sheaves, we had many bushings so that the sheaves would fit different size shafts. If you have room would it be possible to put a couple of "jack screw" holes to remove the bushings by pushing the bushing out if desired? This may save damage from the screwdriver or pry bar on the so very precious parts. Very interesting and nice looking project!
Don


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## cfellows

Don and John,

Thanks for the tip on the jack screws - very good idea! And I thought I knew it all... 

Chuck


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## DICKEYBIRD

(Bowing to the gurus, hat in hand) Thanks, it's perfectly clear now. I'll definitely be using that trick.


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## cfellows

I'm now starting to work on the cams. This will be a built up cam using a 1/4" steel rod for the main camshaft. Each cylinder will have an added piece which contains the intake and the exhaust lobes. 

The first picture shows the cam unit in my machinists vise. I've just used the blade of the square to mark the center of the middle lobe. This will be drilled and tapped for the set screw. The intake and exhaust lobes will be on either side of the center lobe. The diameter of the pieces is .625".

The second picture shows the vise sitting on my dedicated center drill drillpress. I thought the group might be interested in seeing it. I picked it up used on eBay several years ago, added a DC motor on top and a browning timing belt setup for the drive. When I first got it, it had some kind of funky drill chuck adapted to it. I managed to get it off and found a perfect jacobs taper underneath it all that perfectly fit my little Jacobs 0 - 5/16" chuck. I keep a center drill in it and pretty much use it for nothing else.


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## cfellows

More work done tonight. I finished machining the cams.  Probably not quite as good a job as a cam grinder would do, but not bad. 

I used the method prescribed by Randall Cox. The cam blanks are mounted on a 1/4" stub arbor which is affixed to the rotary table. The arbor is centered under the mill spindle. A boring head is mounted in the milling spindle with the boring bare turned inward toward the blank. The radius formed by the arc of the cutting tools is about 5/8" in. The boring bar tip is brought up to the edge of the cam blank. The repeated downward cuts are made with the mill/drill handle, advancing the x-axis into the boring bar cutter .010" each time. When one side of the cam blank is milled down to the primary radius of the cam, the x-axis is locked, then repeated downward cuts are made again, only this them, the rotary table is turned 2-3 degrees between cuts. This is continued on around until the the proper cam lobe is formed. After finishing one lobe, the cam blank is turned over on the arbor and the process is repeated on the second lobe. You have to do some kind of tricky calculations to figure out the starting and end positions on the rotary table to get the two lobes at the right angular separation, in this case 110 degrees. And, since the intake / exhaust valve configurations between the two heads are opposite, the two cam one cam segment wants the 110 degrees separation and the other wants a -110 degrees separation. Took me two days to figure out all the starting and end points! Chuck


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## wareagle

Chuck, the cam looks great! It looks like a tedious task to machine it that way, but it works! I have never thought of cutting cam lobes in that fashion. I'll have to try it sometime!


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## cfellows

wareagle  said:
			
		

> Chuck, the cam looks great! It looks like a tedious task to machine it that way, but it works! I have never thought of cutting cam lobes in that fashion. I'll have to try it sometime!



Thanks! It's a little tedious, but not as bad as it looks. Took me a little over an hour to make all 4 cam lobes.

Chuck


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## Canyonman

Neat method for the cam.

_* Did you make that drill? * _  It's Great! I Love It!!!! 

But then again I most always like the Odd stuffus!!!!! :

If it ever comes up for sale, EMail Me!!!!!!!! ;D

Take Care,   Ken


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## Bogstandard

Lovely bit of work there Chuck.
I have never seen that method before, but as they say, there is always more than one way to skin a cat.
For a composite cam I always went with the method described by E.T. Westbury and made a jig and timing disc for making them in the lathe, now that is tedious. But I think your method is very similar, but using the RT instead of the timing disc, and might be a better way to go if ever I get back into ic engines.
I can't wait to see this one running, a real achievement.
BTW have you seen my latest post on the poppet valve engine, I have managed to get it running on three different cycles by making three different pin cams.

John


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## cfellows

Well, after a sabbatical of a couple of weeks, I'm back into engine building mode. I finished up the 4 valve guides tonight. Not much of a leap, but tomorrow is my last day of work for two weeks and the "General" is going to Austin to visit the kids for a week, soooo... lots of uninterrupted, quality shop time ;D. I hope to get a lot done by the time 2008 rolls around!  Chuck


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## Bogstandard

Lovely work again Chuck, brass or bronze?
This is turning into a really informative project. It is nice to see how an engine gradually comes together, especially from a modified planset.


John


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## cfellows

Thanks, John. A little more progress today. I finished the valve lifters and the valve Lifter Guides as you can see in the photo. I've got to get started on the distributer soon. I can't do much else with the Camshaft until I figure out the distributer design and placement... Chuck


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## cfellows

I got the valves pretty much finished today. I just need to cut them down to the proper length. They were cut from 3/8" hot rolled steel and the stems are 5/32" in diameter. The brass pieces in the picture are the valve guides.






Chuck


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## Powder keg

I really like how this engine is turning out:O) Keep up the good work.


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## cfellows

A few more pictures for your viewing pleasure. I spent two days making the rocker arms, rocker arm posts, and valve spring retainers. These are all niggling little bits that require a lot of time and patience. I'm about finished with all the mechanical parts except for a few retaining rings, setscrews, etc. Next are the fuel and ignition parts... Chuck


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## wareagle

Chuck, your engine is looking great! Just seeing the pictures of it coming together is getting me excited. You should have a very nice model before long. Again, thanks for sharing your build with us! It certainly is an inspiration.


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## Brass_Machine

Wow. That is awesome!


Eric


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## deere_x475guy

Chuck it's looking awesome! Did you use cap screws and let the pushrods center in the allen hole? Also have you thought about using an electronic ignition system? I know there are several guys out there making the electronic ignition for IC engines. Great work keep the pics coming.))


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## cfellows

Thanks, Bob. Yes, the adjustment screws on the rocker arms are just 4-40 socket head cap screws. However, I am going to drill them out with with a ball shaped endmill. Have to buy one first...

I bought the electronic ignition module (TIM6) and exciter ignition coil from Jerry Howell. The exciter coil has two high tension leads, so I don't need a distributer. I still have to figure out where to mount the hall effect transistor. Don't know whether to mount it in the middle of the cam shaft or on the outboard end. And, I have to solder the TIM6 together. Shouldn't be too difficult... I've soldered a lot of circuits together over the years.

My real dilemna at the moment is deciding which carburetor to build. I have plans for Jerry Howell's carburetor as well as the plans in Randall Cox's Open Column 6. I have a few other designs to pick from as well. None of them are exactly what I'm looking for and I don't know enough about Carburetor design to come up with my own.

Chuck


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## gilessim

That engine is looking fantastic!, how did you cut that profile on the bottom of the rocker arms?....Giles


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## cfellows

gilessim  said:
			
		

> That engine is looking fantastic!, how did you cut that profile on the bottom of the rocker arms?....Giles



I milled the bottom profiles using a 1/4" carbide end mill in my mill/drill. I have a small, secondary vise I built which I hold in the jaws of the big vise. The small vise holds the work so I can mill the edges of small pieces. I originally built it to make connecting rods, but I found that it get's used for a lot of other things. Here's some pictures:











For reference, the end mill shown is a 5/8"





Chuck


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## cfellows

Finally made some more progress on my Open Column twin. After being stalled for far too long, I've come up with a design for the intake manifold and the carb. I decided on a functional design similar to that used on the Upshur T-Head marine engine. I still have to make the innards for the carb, but that should be pretty straight forward. I also have to solder the manifold together after I get the manifold holes and matching holes in the heads drilled and tapped. And, I have to close up the drilled holes in the ends of the manifold where the carb attaches.

You can also see the aluminum disk on the end of the camshaft that will hold the magnets for the hall effect ignition pick up.

Chuck


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## deere_x475guy

Chuck things are coming along nicely it would appear. I always look forward to seeing your progress on this engine, keep up the good work.


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## tel

That's a seriously nice engine. After 30 years of building steam engines, I'm still not quite sure that my skills are up to taking on something like that


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## cfellows

tel  said:
			
		

> That's a seriously nice engine. After 30 years of building steam engines, I'm still not quite sure that my skills are up to taking on something like that



Thanks! From a machining standpoint, there's not much difference between gas engines and steam engines. Gas engines are just more complex, since they have the additional worry of fuel and ignition systems.

Chuck


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## cfellows

After a sebatical of a couple of months I got some more done on my open column twin. Actually, I was having a problem getting the valves to seal and I've been pouting about it for two months! 

I finally solved the problem tonight. I dressed the back of a small, dremel mounted grinding wheel to 45 degrees to match the valve seats. I then made brass bushing that fit inside the valve guide and provided the right inside diameter for the shank on the dremel grinding wheel. 

I pushed the brass bushing into the valve seat from the bottom side, then pushed the shank of the grinding wheel up through the bushing so the dressed back of the stone rested in the valve seat. Using a variable speed electric drill I spun the stone until the seats were nice and shiny all the way around.

I put the engine all back together and I now have good compression on both cylinders! Maybe I can get this thing finished up and running.


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## Florian

Hi cfellows

I know that for grinding in the valves of engines, they use grinding compound. You can also use some toothpaste (the one with abrasive particles). Then you put some paste on the valve seat and grind the valve in during some minutes (depends on how good it was prepared before, on what materials were used for the valve and its seat and on what you are using for grinding compound)

Florian


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## cfellows

Florian  said:
			
		

> I know that for grinding in the valves of engines, they use grinding compound. You can also use some toothpaste (the one with abrasive particles). Then you put some paste on the valve seat and grind the valve in during some minutes (depends on how good it was prepared before, on what materials were used for the valve and its seat and on what you are using for grinding compound)



Yeah, I tried that initially, but the valve seats were too far off to lap. I needed the grinder to get the seats trued up more. I should probably go back now and lap the valves in.

Chuck


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## Bogstandard

Hi Chuck,

That engine is coming on real well.

A real crappy pic here, but if you can just see, I embedded the transistor into a groove machined into an ali block using epoxy, to protect it. The ali bock was then fitted to an arm that could pivot around the disc with the magnet in it. This gives the advance/retard for when the engine warms up.

Jerry Howell is a great chap to deal with, I had trouble working out the size of disc required and how many magnets, but he soon put me on the right road by explaining it all, and the tim system works great. Fires up every time.

John


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## raym 11

Hi Chuck;

Nice engine! 
I don't have the _know how _ to design my own.

A while back we discussed the carburetor on my Upshure Twin. I have since built the Ridders foam carb and it runs the engine mucho better. I am just finishing a scaled up foam carb with a rectangular section verses the cylindrical version. I an hoping it will take less adjustment when the fuel level changes as the liquid /vapor interface area will remain constant.

Will be interested to know how your engine runs with the carburetor shown.
What is the block with the horizontal hole located on the manifold between the air/fuel mix block and the heads?

Ray


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## cfellows

ElGringo  said:
			
		

> Hi Chuck;
> 
> Nice engine!
> I don't have the _know how _ to design my own.
> 
> What is the block with the horizontal hole located on the manifold between the air/fuel mix block and the heads?



Thanks for the compliment. The block you mention is just part of the intake manifold.

Chuck


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## cfellows

I started this engine back in the fall of 2007 and finally got it running. The past couple of days, I installed some points, a condenser and a dual wire coil I got from Jerry Howell. Hooked it up to a vapor carb and finally got it started. Clearly got lots of tuning to do to get it to run the way I want, but it's a start!

[ame=http://www.youtube.com/watch?v=jZTSmiSO-oE]http://www.youtube.com/watch?v=jZTSmiSO-oE[/ame]

Chuck


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## chucketn

I know nothing about IC engines, but, why the different diameters on the left flywheel?

Chuck in E. TN


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## cfellows

chucketn  said:
			
		

> I know nothing about IC engines, but, why the different diameters on the left flywheel?
> 
> Chuck in E. TN



It's all the same diameter. It has a V-groove in it so I could run it with an electric motor and a tiny v-belt to break it in before I tried to start it. Also works to hook up an electric starter if it's hard to start.

Chuck


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## Brian Rupnow

Very nice, Chuck. I'm glad you found a way to get the valves to seat.---Brian


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## steamer

Great looking engine Chuck! I really liked the twins.  with the cranks at 180, what's the sound like?

Sorry no speakers.......

Dave


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## cfellows

Brian Rupnow  said:
			
		

> Very nice, Chuck. I'm glad you found a way to get the valves to seat.---Brian



Thanks, Brian. I just hooked an electric motor up to it and run it for about half an hour with no fuel or spark. That seemed to bed everything in.




			
				steamer  said:
			
		

> Great looking engine Chuck! I really liked the twins. with the cranks at 180, what's the sound like?
> 
> Sorry no speakers.......
> 
> Dave



Thanks, Dave. The sound isn't where I want it yet. It's running too fast, it's only firing most of the time on one cylinder, and the one cylinder is missing a lot. I want it to eventually have the syncopated sound of an old John Deere or a two cylinder Lister. But I have to get it hitting on both cylinders and running a lot slower. I probably will have to change over to a carb rather than the vapor carb. I'll be trying a few things, including adding an outer ring to the flywheels to make them heavier. Stand by...

Chuck


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## b.lindsey

Chuck, that is one beautiful engine !! As has already been said...awesome!!

Bill


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## GailInNM

First pops are wonderful. Congratulations. Thm: Thm:
Gail in NM


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## Maryak

GailInNM  said:
			
		

> First pops are wonderful. Congratulations. Thm: Thm:
> Gail in NM



Me too. :bow:

Best Regards
Bob


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## gbritnell

Hi Chuck,
Nice job on the twin. Are you going to stay with the vapor fuel setup?
George


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## cfellows

gbritnell  said:
			
		

> Hi Chuck,
> Nice job on the twin. Are you going to stay with the vapor fuel setup?
> George



Thanks, George. I'm having a problem with the vapor carb splashing fuel up into the intake tube and flooding the engine. If I do stay with the vapor carb, I'll have to make a taller one so the liquid fuel is well below the fuel line to the engine. I also have several model airplane carbs that I could try to adapt, although I think they are all too large. The venturi on the smallest is .25" or more. Another option would be to duplicate the carburetor designed by Randall Cox for his Open Column Six engine featured in Model Engine Builder since my Open Column Twin is based on Randall's design.

Chuck


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## cfellows

I added a half inch thick steel ring to each of the flywheels today. I figure I probably more than doubled the weight. They are now 6" diameter. Turned the rings to an interference fit then heated them as hot as I could get them with my mapp gas torch. I left a small shoulder in the bottom of each ring as a stop for the flywheel to rest on. The first one went real nice and dropped right in with only a little nudging to get it straight. Unfortunately the second went in about half way and stuck. Luckily I was able to use my 20 ton press to coax it into place. I had to work my way around the rim a little at a time and it took me a full 15 minutes to drive it home. But it is now in and straight. This picture was taken before I started cleaning them up. I'm doing some tapering and rounding to make it look like one integrated piece.






Chuck


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## starnovice

Chuck,
Did you ever get this project finished?  Glad to hear you made it to the GEARS show I'm sorry I never got to meet you there.

Pat Wicker


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