Download the comp prep manual from the datsun.org site's literature page.
The manual says a stock chamber is 45.7cc's. Compressed head gasket is .055
or 9.2cc's (mine measured .050 and 7.8cc's). Keep in mind that valve seat
depth affects chamber volume. That had me scratching my head for a full 2
days. My number 4 intake valve was seating .050 deeper than any of the
others. Do the math and that adds up to 2cc's of additional volume in that
chamber - I thought I'd cut too much out of the chamber but couldn't see how
I'd removed an extra 2cc's. Turns out that by eye I had them all with in
0.2cc's. It's a good idea to cc them all before you do any modification so
that you know where your baseline is. Don't just rely on what the manual
says a stock (new) chamber will hold.
FWIW the manual also says that each .005 cut from the head will reduce
unswept volume by .81cc's
Brian '69 2000
http://web.tampabay.rr.com/oilleak/
-----Original Message-----
I am bumping compression on the ol' U20 and need the
following info if anyone has it, or can get it: Compressed head gasket
thickness (I threw mine away), and stock combustion chamber volume.
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