Hello I'm building a 440 with Kb Icon Pistons for a drag application. It's a got stock crank Scat rods and flat top Icons. I have .003 clear on mains .0025-.0028 clear on rod bear and .006-.0065 piston to wall clearance. My question is just turning the crank while assembling it I can hear the Pistons rock at bdc or tdc or both. It's very consistent. It is a sound I have heard before on other engines I have built. Mostly on longer storke small chevs with short compression heights and short skirts. I have always attributed the noise to the short skirts and loose piston to wall clear. But this engine seems louder. Wondering if the rather large compression height (by comparison) has something to do with noise? I did oil skirts and rings during assembly. Have any of you heard this before with these Pistons before during assembly?
Thanks

What it does cold, turning by hand means nothing. What matters is the clearance or lack of clearance when it's at operating temperature. Stock motors have audible piston slap at much smaller clearances, and most of them have offset pins that counteract slap.

So what does it mean? The cold piston is rocking in the bore.

R.

I too run the Icon pistons. At first start up and up to engine running temp. I have piston slap noise. Once running temp is reached, it is as quiet as a mouse. I don't think you have anything to worry about. Just my two cents.....

i running some icon 836's at .006". pretty noisey when cold.

Better to hear 'em than to smell 'em.