sabastian458

iTrader: (5)

I'm wrapping up my 403 LS2 build and the last parties measuring piston/deck clearance for head gaskets. Using a 4.5 inch bridge with micrometer set to "0.000" off the deck, I found that my measurement has fluctuations. The top portion of the piston, where "quench" is at, the piston measures any where from .006-.007 above deck to as low as .015 below deck, when the piston is rocked in the bore.

I rotated the engine off TDC and measured the opposing bank and found the same situation. I know using forged Pistons required specific piston/bore clearance, in which I had the block bored/honed to (with torque plate) by my machine shop, but is this rock excessive? Or am I being paranoid over nothing and should use the above deck measurement for calculating proper "quench" for head gasket thickness?

jayyk31

iTrader: (2)

Mine was .006 out of the hole also. It also rocked a bunch but that is normal with 2618 forged pistons, which require more clearance in the bore. The stock hyper pistons shouldn't rock as much because they have really tight clearance in the bore.

That's how I measured for my headgasket. I found tdc, then rocked the piston back and forth, while taking my measurement on the edge of the piston, not the middle.

With .006 out I am using a .045 cometic MLS HG giving me around 39 squish.

KCS

iTrader: (20)

I've found that .020" Rock is pretty normal at TDC for the 2618 alloy forged pistons. It's largely influenced by the piston-wall clearance and the skirt design, but it should be fine.

sabastian458

iTrader: (5)

Thank y'all!

heykw

KCS

iTrader: (20)