"I sure was not clear in my notes above, maybe this will help.
3 issues with "piston clearance"
(I hope the experts will forgive/correct my explanation)
1) piston to bore clearance: .0020-.0030".
I like tight, but be careful and warm it up before stressing it
Millennium will plate the cylinder bores, then hone them down to a size which gives the correct Piston-to-cylinder clearance.
When you buy a kit (block+pistons) that clearance has already been accomplished but always good to check.
2) piston to head clearance as it goes thru TDC = quench/squish height
a safe quench = .040",
lotsa folks go tighter, but gotta be careful.
Quench is impacted by cy block height, rod length, base spacer, base gasket, head gasket, piston design.
3) Piston To Valve clearance: as the exh valve closes and intake opens during overlap and piston goes thru TDC, piston gets closest to valves.
axial: Exh PTV =.080", int PTV = .060" is safe;
lotsa folks go tighter, but be careful
PTV is impacted by piston valve pocket depth, quench, how much the head is skimmed, how deep the valve seats are sunk, how "big" yr cams are, what CL's you have the cams set at, even lash setting.
I hope this doesn't muddy things..."
What's that smell? Now I feel something sliding down the back of my throat. Oh, that's just my brain melting and oozing out of my skull. Just kidding - that all sounds very technical but what I will probably do is have my tuner send the pistons with the head and explain to Millennium what I'm trying to achieve. I'm pretty sure Millennium will know what to do and I have a lot of confidence in the tuner I'm using for this project. For anyone in Chicago his name is Bill Pehanich (Billy P.) and he runs BPR) Racing in Crestwood, IL. I used Elton Fish of EFR Racing for my turbo (another great, great tuner) but the drive out to his place from mine was a bit much.
What is quench/squish? Thanks.
Fast