piston size question

Does anyone have an actual piston diameter measurement for a new, standard 225 piston? I'm rebuilding a 225 and I have the Cyl bore measurements and the old piston measurements. I want to see how much clearance I would have with new pistons without actually ordering them. I'm getting measurements like 3.7475 on an old piston which means a clearance of .0025 when the manual says the service limit is .0015. Does.001-.0015 seem too tight? Also I can't seem to find the correct place to measure the piston, I think I got it right but not sure.

Josh

 

IIRC the standard bore is 3.75. Hope this helps
Steve

 

No, not the bore the actual new piston size. Is it 3.749, or 3.7495 or 3.7489 or 3.7497 etc?


Josh

 

The largest diameter is the right place to measure, most pistons are actually stepped down in size at least in 2 different locations and can be more. As far as the piston fit you're suppose to take the piston to the guy thats boring and honing the block. .0015 is a decent fit for a standard piston.

 

Thanks,
Josh

 

The standard on rebuilds is to rebore. This eliminates taper and out of roundness. This also allows the machinist to rebore to the piston diameter.