Piston to Bore clearance???
Piston to Bore clearance??? I'm about to change heads on my car. Ever since I've had the stroker, I've always had major piston slap at start up. Now, it goes away after about 5 minutes or until it gets warm. I removed my old heads and I go to clean up the inside of the bores and there is little play when moving the piston around the bore. This is in all the bores. According to the build sheet, the pistons are 4.005 with a .0045 piston to bore clearance. Is this what's causing my piston slap and is it OK?????????
Yes, the stock stroke ls1s are known for piston slap, and when we add a longer stroke we make it worse. So your good, that is what it suppose to be doing.
Those didn't really have piston slap issues, and with a properly built bottom end with good clearances there's no reason for it to have these issues. An engine is not "supposed" to rock the pistons against the liners...that's an issue (albeit a small and almost insignificant issue as most engines are ok with piston slap).
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Joined: Jun 2011
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From: Katy, TX
Stock stroke LS1s don't have 4.000 bore which I can only assume that's what the OP started with. Thus this is not an LS1 but most likely an LS2 or an iron LQ9/4.
Those didn't really have piston slap issues, and with a properly built bottom end with good clearances there's no reason for it to have these issues. An engine is not "supposed" to rock the pistons against the liners...that's an issue (albeit a small and almost insignificant issue as most engines are ok with piston slap).
Those didn't really have piston slap issues, and with a properly built bottom end with good clearances there's no reason for it to have these issues. An engine is not "supposed" to rock the pistons against the liners...that's an issue (albeit a small and almost insignificant issue as most engines are ok with piston slap).
what clearances are you referring to?
I've never heard an ls1 yet that didn't have the cold piston slap. If it quiets down when warmed up I wouldn't worry about it. .0045" is going to definitely cause cold piston slap. You obviously are running forged if it quiets down after it warms up.
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The pistons have a barrel shape to them from top to bottom. From the top, the pistons seem to move around a lot, but the minimum clearance of .0045" is a little more than the thickness of a sheet of paper. As everything heats up, as noted, parts expand and the clearances tighten up.
