Cylinder diameter VS. piston diameter - Page 3 - Hot Rod Forum : Hotrodders Bulletin Board -- Hot Rod Forum

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  #31 (permalink)  
Old 09-05-2010, 04:59 PM
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Originally Posted by Custom10
OK so the coating must be 0.005 or so all the way round and it does actually squish down under some pressure, perfect fit, hmm LS1 magic,

So the middle is big and each end top/bottom is smaller?
Coating is thinner than that, but yes. you are correct.

Just some #'s for example off the top of my head, not in particular to the LS question, just general info:

Very bottom of skirt might only be .0005" smaller than the bore, but the top of the piston might be .010"-.015" smaller(some forgings are .035" smaller at the top) than the bore. A lot more thermal expansion at the top, this is why they are barrel shaped. Fattest part of the barrel shape is usually only about 1/2-1" above the bottom of the skirt.

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Old 09-05-2010, 05:18 PM
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OK well good info, and really somehow these tight/interference fit motors work so thanks

Now with respect the OP

So my question is this: I know that a stock 350 has a bore of 4 inches right? So why am I measuring 4.020 - 4.030? Is this engine bored over? Or is the piston what's supposed to be 4 inches? If I were to replace the pistons, what "bore" would I purchase, and would that "bore" be referring to; the actual piston diameter, or the actual cylinder diameter?
Id say he could go with a 30 over slug and hone to fit? or should he get 40 over and really ruff it up?
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  #33 (permalink)  
Old 09-05-2010, 09:31 PM
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Just so you guys know, the Op asked the question in regards to his bore vs. piston size on 1-28-10. I would think he had it figured out by now....maybe not.
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