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Scratch Built Radials

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Mad MAC

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I am sure there was a thread about building radials with motorcycle cylinders (can't find it) but it was a bit short on actual working examples.

Here's two by a kiwi Russell Sutton (possibly slightly mad he spent 25 years in WA).
the 9 cylinder

the 14 cylinder (not finished yet)
 

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Grumpy Cynic
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I've often wondered how many radials have been build using overhead cams. Have there ever been any production versions?

It does open up some options. Should be easy enough to convert a lot of OHC chain/belt systems to shaft and gear.
 

Riggerrob

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Back during the 1920s (?) a handful of radials were built with over-head cams. They had a series of complex cam-shafts running around the cylinder heads ... in a circle.
 

poormansairforce

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I am sure there was a thread about building radials with motorcycle cylinders (can't find it) but it was a bit short on actual working examples.

Here's two by a kiwi Russell Sutton (possibly slightly mad he spent 25 years in WA).
the 9 cylinder

the 14 cylinder (not finished yet)
That's something that I've been looking at in using some thumper cylinders to build a radial but I was trying to retain the chain drive overhead cam.
 

pfarber

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Looks cool, but not flyable. Airboat motor? Sure. But in the front of an AC? That gear system looks heavy and those jugs don't seem to have the same cooling area as a Lyco-saur.
 

pictsidhe

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125cc-Cg-Motorcycle-Engine.jpg

Honda CG engine. I think clones go up to 250cc now. The cam followers have a pivot in the bottom of the bottom of the cylinder. Looks ripe for a cam ring conversion to me...
 

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Grumpy Cynic
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I'm thinking that a bevel gear drive OHC might use more OTS parts. One gear on the crank drives all of the cams without any intermediary parts. The drive shafts can be any length needed. Just replace the stock cam belt/chain gear with a bevel/hypoid.


I'd not seen the Honda system before. Gives me an idea.........A dangerous distraction for me.
 

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pictsidhe

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The CG crank gear is press fit with 22mm ID. Could be used along with a chain drive?. If you could make a cam ring and new followers, the CG barrels would just drop on, possibly with a single cam. I'd probably look at CG100/125 heads on 250 barrels to bring peak torque down to radial revs.
 

Niels

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Aug 15, 2019
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No way! Sidevalve heads are a thermal efficiency disaster due to really poor surface/volume ratio and low knock resistance.
A small two stroke piston stroking longer/faster with a single exhaust sidevalve will not be much more detonating prone than Lycosaurs
 
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