Quote:
Originally Posted by Elarson
Here's the pix of the piston that got killed by binding in the bore.
To make a nitro engine survive, the thing has to be super loose.
Piston-to-wall has to be pretty sloppy
Mains need .007+ clearance (when you can grab the crank nose with your hand and make it clunk up and down, you're about right)
Valve guides need to be loose so you don't hang a valve and grenade the whole engine
If the exhaust valve heads are distorted a bit and won't seal after a run, it's ok.....they'll straighten up the next time you pour the coals to it.
Eric
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That skirt damage was at .009"-.0095" piston to wall clearance. Problem went away almost entirely at .0115"-.012" The engine will tell you what it wants to be happy. Just have to look and listen to what it says.