Variation on a Howell V-Twin

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nx06563

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Thought some of you might want to see my latest project. It is a OHC version of Jerry Howell's V-Twin. I have built his engine and it was a great design but it taxed my abilites to the limit even though the one I built runs great. I thought I would try to create a design without the complicated cam gear system so I built a test "mule" of a single cylinder version with an OHC. It runs great but like a single cylinder it vibrates so bad it is hard to keep on the bench. I have another thread that shows the single.
I will not have time to get the twin running before I leave for Arizona for the winter but I will work on the drawings this winter. I did all the design work for the new parts on Fusion 360 which was a learning experience in itself. I will clean up the drawings of all the parts that I have modified and make them available when I am done. Jerrys design is copyrighted so any part that I did not modify (pistons, rods, valve cages, etc) you will have to get by ordering Jerry's original design. Please support the web site and order the the prints
Thanks for looking!

P1090450.JPG

P1090452.JPG

V-Twin.jpg
 

Rudy

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Very inspiring project! No wonder the cam driven valve train is so popular in modern engines. Very simple and clever design.
Is it set screws on the cam lobes I see on your picture? Is this considered to be a permanent way of making a cam? Would say it´s easier making a cam this way and I like the idea of being able to experiment with the timing.
I´m considering a V-twin for my next project. Howel´s or the Hoglet.

Rudy
 

nx06563

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Yes, the cams are held in place by dog point set screws. I am hoping it is a permanent method. I read an article I found online by Graham Meek about making radial flank cams. He used pins to hold the cams in place. After a little study I figured I could use 6-32 dog point set screws which have a .086 dia dog point rather than pins which would be quite difficult to remove once in place. The set screws seat into a 3/32 keyway cut directly under the highest point on the cam. lThere is an access hole on the base circle of the cam direcly opposite the keyway. This way the cams are removeable if necessary. I do this for a hobby so my engines dont run for hours on end so I never heat treat cams though I suppose you could.
The cam flanks are cut on the lathe using a tool to hold them and then the base circle is cut on the mill with a rotary table. much easier for me than nibbling the cams out on a lathe. I have built tools for 1/4 ID cams and 5/16 ID cams. I used the 1/4 ID cams on the single cylinder version that I built. Pretty easy to vary cam timing changing the setscrew holes in the camshaft.

cam turn tool20181022.jpg


cam tool20181022.jpg
 

nx06563

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This is how far I have gotten. I leave for Arizona for the winter next week so there is too much to do to get it running this year but I will dress the prints up and make them available for anyone who wants them. I am assuming it will run since I have compression and air is coming out the exhaust and in the intake when I spin it.
I have to finish the ignition which is easy since I am using RCExel airplane ignitions, make some throttle linkage, make exhaust manifolds, make a strarter hub, and mount it to the box.

Will finish in the spring.

20181026_193805.jpg
 

nx06563

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I have been back from Arizona about a month and have finished the work on the OHC V-Twin. I only have to check it over to make sure the bottom plate is sealed put oil in it and give it a try.
I am currently an expectant new father waiting to give birtth to my first kidney stone. It hurts to stand for long so I will give an update to the starting process when I have it running. I know my skills so this may take some time.
Once it is running I will start the process of cleaning up the prints so I can make them available if anyone is interested.
 

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nx06563

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Well, I finally have it running. I am finding that its hard to get things done in the shop in the summer. Too many other projects in the yard and I have fishing and golf to get done too.

I had a "little" problem while I was getting it running. I had made a two piece Crankshaft since at the time I didn't have quite enough steel to turn both sides from one piece. I used a piece of 1/2" drill rod that had been threaded for a nut to hold the flywheel and a keyway for the flywheel. I pressed this piece into the crank disk.
When I was trying to start the engine it kicked back and spun the flywheel shaft in the crank disk, which in turn threw things off so the rod caught the corner to the recess on the crank disk. Long story short I had to make a new crankshaft and a new rod.
It now starts and runs quite nicely. I will video it and post the video as soon as I can get my wife to run the camera.

Next project will be to clean up the drawing and post them.

Thanks for looking.
 

nx06563

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It finally runs. As you will notice I was too lazy to build Jerry's carbs so I used model airplane carbs to make it easier to debug it for start up.


I havent put a video on for years so I hope this works.
 

ShopShoe

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That's nice. It sounds nice and steady and I like the way it reacts to throttle control. Don't feel bad about the model airplane carbs.

Do you have another project in the works?

--ShopShoe
 
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