67 Cuda: disappointing dyno numbers, need some advice!

Brandt Fonda said
it is a 74 block but it was built around '95ish, talked to him again today he says pistons are TRW 9.5:1, forged and crank is forged. also heads are closed chamber? Not sure if 308's were closed chamber? He drove the engine in a Demon till wrecked, then he put it in Cuda. The Cuda sat after he put the motor in it for about 15 years why it looks rough in those pics. Before I got it back running I sprayed seafoam in each spark plug hole till full. Let sit for a couple days then turned engine over by hand. It turned very smoothly for several rotations changed the oil and fired it up. Since then I have changed the oil 2 more times in less than 1.5k miles. Maybe corrosion throughout the engine could be a problem?View attachment 1715358816

308’s are open chamber heads. 302’s were closed chamber, but they have the smaller 1.78/1.50 valves and the smaller 318 sized ports.

Only way to get 308’s to be closed chamber is to mill the living crap out of them.

Brandt Fonda said
Ill try to have the compression numbers on Friday

maybe one of you guys could get a close guess of compression ratio with 360la block bored .30 stock stroke, 308 heads with I think 73cc ?

I did a compression ratio chart online and got 10.33:1
values I used:
bore size: 4.07 stroke: 3.58 Gasket bore diameter: 4.18
compressed gasket thickness: .039 combustion chamber: 73cc
0 for piston dome and piston deck height.

There’s no point in messing around with compression calculators with what you’ve got. You’d be guessing on almost everything. Could easily be anywhere from 8:1 to 10:1 based on the info you have. You don’t know how far down in the cylinders the pistons are. You don’t know how big the valve reliefs are, which changes the volume. You don’t know how big the head chambers are.

And on that note, 308’s can be anywhere from 65cc’s to 72.