Thread: piston to cyl. clearance

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i got my pistons overr the weekend for the 5.7 im rebuilding. the block has been bored .030 over. i checked the piston to wall clearance and come up with .oo2 using a feeler gauge. but it seems pretty tight to me. what are most of you engine builders coming up with when you put one together.

Originally posted by 891500guy
i got my pistons overr the weekend for the 5.7 im rebuilding. the block has been bored .030 over. i checked the piston to wall clearance and come up with .oo2 using a feeler gauge. but it seems pretty tight to me. what are most of you engine builders coming up with when you put one together.

It's pretty tough to measure piston to wall clearance using a feeler gauge with the pistons in the bore. The proper way to measure it is with the piston out. The clearance is usually .001 for every 1" of cylinder bore, on a stock rebuild.

Originally posted by 891500guy
i got my pistons overr the weekend for the 5.7 im rebuilding. the block has been bored .030 over. i checked the piston to wall clearance and come up with .oo2 using a feeler gauge. but it seems pretty tight to me. what are most of you engine builders coming up with when you put one together.

Piston to wall clearance varies depending on what type of piston you’re using. The material, design and intended usage all figure in to what this dimension should be. Your best bet is to follow the manufacturer's recommendations for how you are going to use their product.

Or, you can experiment and start paying for your education.

Most the time the machinist wants the pistons when he bores the block,so's he can finish hone for the proper clearence...

Originally posted by pro60chevy
It's pretty tough to measure piston to wall clearance using a feeler gauge with the pistons in the bore. The proper way to measure it is with the piston out. The clearance is usually .001 for every 1" of cylinder bore, on a stock rebuild.

To clarify what Pro60 said, best way to measure is with micrometers. Measure the piston with an outside mike and the cylinder with an inside mike then subtract to find the difference and divide it by 2.

Pat