Measuring Piston to bore clearance.
02-23-2005, 11:25 AM
#1
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Measuring Piston to bore clearance. I want to determine my piston to bore clearance. I've measure the bore at several locations and am within published spec (about 3.898).
Where do you measure the piston? I seem to be way undersized at the top.
Is there a specific location on the piston that is speced by G.M. for measuring the piston diameter?
Sam.
Where do you measure the piston? I seem to be way undersized at the top.
Is there a specific location on the piston that is speced by G.M. for measuring the piston diameter?
Sam.
02-23-2005, 12:41 PM
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The piston isn't symetrical for the reason that the top of the piston runs much hotter than the bottom.
From what I've seen people check at multiple locations.
I've actually never had to worry about it.
Loose never bothered me.
From what I've seen people check at multiple locations.
I've actually never had to worry about it.
Loose never bothered me.
02-23-2005, 01:23 PM
#5
You have to measure the piston in the skirt area as the ring area is smaller. You need to go with recomendations of piston manufacturer. Forged pistons traditionally need more clearance because the forgings expand more than cast(ussusally stock) pistons.
This depends on the alloys mix though. I am installing mahle forged pistons with a low expansion alloy and they only need 3 to 4 thousand clearance which is great cause you have a quiet piston when cold and the strength of a forging. Loose engines may make a little bit more power but ring wear will be severe with frequent rebuilds.
This depends on the alloys mix though. I am installing mahle forged pistons with a low expansion alloy and they only need 3 to 4 thousand clearance which is great cause you have a quiet piston when cold and the strength of a forging. Loose engines may make a little bit more power but ring wear will be severe with frequent rebuilds.
