Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Cylinder diameter VS. piston diameter
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Old 01-28-2010, 05:04 PM
Intense RT Intense RT is offline
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Originally Posted by XeroVolume
So just to clarify, the ACTUAL stock cylinder of a 350 will measure 4.000 inches and therefore a piston that says it's bore is 4.000 will actually measure slightly smaller in order to fit inside the cylinder?

If I were to purchase new pistons for example from, and the piston specs say the bore is 4.000, will they fit inside a cylinder that is EXACTLY 4.000? They would have to be slightly smaller right? Sorry I'm just a little confused.

If I have my engine bored to .060 over, will I buy pistons that say .060 over or will they need to be smaller?
To your first paragraph, yes. Second, yes also.

BTW, engines nowadays have come a long way. New LS engines actually have roughly a couple tenths interference fit when new and have skirt coatings. Hyper pistons expand much less and when at operating temp the cyl walls expand more than the piston. Tighter fit, less blowby, less emissions.
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