David Vizard, Uncle Tony's garage, Unity motorsport. Mission impossible Dodge 302 Head porting

George Jets said

OK
The head gaskets are the .028 ths Mr. Gaskets.

And the Factory 9.2:1 valve relief flat top pistons (std.) sit .040 down in the hole.

I know cause I measured them. The 1969 318 block was not decked, untouched .

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With everything figured in on that '69 318 build, we figured came out to 9.5:1, Pistons, 302 closed chamber heads, and the thin head gaskets.

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That was also figuring a little deduction for the valve reliefs in the pistons too.

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OK, Brian just now got back to me with his cr calculations.

59cc 302 chambers

View attachment 1716035125

Brian's Quote:

"I have numbers he will need to be accurate. My calculation is 9.6:1."

Click to expand...

You cant take an accurate measurement like that. You need a plate or the water you're using will buldge and read HIGHER than is actual. That could be 2cc or so off. The heads are born as 64cc and have been about the only 318 head to be spot on with printed specs.
As they are in the pic.. they probably flow like coffee straws...and you'll merely feel off idle umph that will instantly plain and fall off with rpm after 3k from the higher compression gained with 7 cc less than stock... funny thing is it will pull a nice amount of oil past the old used rings and when you pull them for a swap to another 45 yr old short block , they will be oily and crusted...and will need a tear down, tank and seat touch before going back together..if not hard seats too.
Something to remember about those thin castings is that they were warping a lot if they didn't crack so you will find a lot of remand 302 and 714 heads that have had a ton milled off of them to make them flat...or to get surface cracking out. A dead giveaway is the point between the valves on the closed side will be wider and wider the more milling.