Piston to Head Spec? Options

[Jetsetsurfshop]

I'm in the process of ordering some custom pistons and my Dad and I were thinking there must be a preferred distance from piston to head for the best combustion. Any thoughts?
(Its a 4, not a 6)
Thanks
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[stugray]

If they shaved the heads down to get the comb chambers to 49 ccs, they may have shaved them too far.

I tried to do the very same thing, but the Porsche mechanic/machinst advised against it.
He said that machining the heads that far will make the metal too thin where the exhaust studs thread in risking blowing them out.

So he shaved them down for me but only to the point where I had 54 ccs comb chamber volume.

The deck height requirement of > ~0.028 (call it .030 for some margin) is to keep the piston tops from hitting the flat portion of the head when the pistons reach max temp.

I have .035 and ~.5 valve lift (webcam 86b) and have plenty of clearance from the valves hitting the piston (stock valves).

Once you get everything dialed in, do the clay method of checking valve clearance.
Put a lump of clay on the piston , reassemble, and crank once around.
Then disassemble and measure the indentations in the clay.

http://www.914world.com/bbs2/index.php?showtopic=200247