I started taking my 396 apart today and found quite a bit of cylinder wall wear and I was quite surprised with the amount of clearance between the piston and the wall. I took some pictures of the tear down. This engine has less than 500 miles on it and is supposed to be able to handle high amounts of Nitrous. The pistons appear to be 20 thousandths smaller than the cylinder walls. I need your opinions on whether or not this is what you would want in your motor. I don't know alot, but I don't think I want that much clearance in there. Am I wrong?

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Chris
93 Indy Pace Car
Just like 99% of you, it ain't stock!
396ci and a TH400 by A.R.E.
If you're interested in doing business with Agostino Racing, contact me first. I'd be more than happy to share my experience.
cmcmillen@carolina.rr.com

 

The head of the piston is smaller than the shirt. This is to allow the top of the piston to expand as the top runs alot hotter than the shirt. you may only have .001 clearance on the shirt but it will look like .020 to .030 looking at the top of piston on a assembled short block.
NORMAL!!!!!

 

Why are you tearing into a 396 engine with 500 miles on it? Just curious. Also, there are very specific ways to measure a piston, and be aware that pistons are an eccentric shape on the skirt, and like the other guy said, smaller up top. The bores, however must be perfectly round on a new engine. They will get egg shaped over time from the thrust.