How can the compression be that good when the pistons are usually 0.080" in the bore and mopar cylinder heads have big chambers, like 65cc plus. I don't think that a 0.028" head gasket alone would do it.
The early LA 318 was built as a 9.2:1 engine.
It may or may not actually measure out to that.
I think they were 67-69.
Most "mid production" LA 318 engines were built to 8.8:1.
Again, they may or may not actually spec out to that.
Then, the mid 80's to early 90's LA "roller" engines were again built to 9.2:1.
We had a member a few years ago tear one down and measure. IIRC he got 9.18:1.
Close enough for me to be a believer that they got better with their math and tolerances on the roller LA engines.
Not sure why hardly anyone seems to know, care, or factor this.
Almost half a point of "free compression" has got to be a good thing.