Geoff---If your '74 head has NEVER been skimmed, it should measure 3.580
thick, and its compression at 7.5:1. To get the compression up to 9.5:1
it's necessary to mill quite a bit more from the head than the amount
the shop seems willing to take off. I believe you could safely take off
a total of closer to .150 to put you near the compression ratio you say
you want. Don't go below 3.400, given the low octane now available at
our pumps, unless other modifications to the engine are carried out. The
formula for "Milling the Head" can be found in the next 6PACK
NEWSLETTER. ; - )
Dick T.
'73
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