OP I feel your pain, I have been where you are at, my first 396 I had, had 7.7 to 1 compression with a 272 crane cam which believe is something like 216 @ .050" with .515 lift, now at the time I did not know what my compression was, but with that set up I had 150 psi cranking compression and the engine ran best with 44 degrees total timing and ran 14.40 at 99 mph with a stock th350 tranny and 2.56 single spinner in a 3800lbs camaro.
later on I changed came to like a 284 crane cam which I think was 228 @ .050" and that dropped my cranking compression to 135 psi the engine/car slowed down, I was like in the 15's and struggled for a few race season to get my car back to 14's trying 4.56 gear posi , new tranny, 2500 stall, 750 carb eddy intake, no matter what I did my car was no faster then my first time ever to the track with many serveral thousands dollars spent.
the one thing that never changed was the compression everything else was bigger and better.
Never the less, I finally took the advise of my mentor and took the heads off, I found out my pistons was something like .055 down the hole, my head gasket was the .040" thick and my heads was the large open chamber, and the pistons was the cheap rebuilder kind with the "diamond" shape dome which isn't worth much in compression.
So after all the figuring and measuring the compression came to 7.7 to 1, no wonder my car never responded to nothing.
So for 200 bucks I bought some 96 cc very used up closed chambered heads and thin
steel shim gasket and got my compression to 8.8 to 1 with those cc heads.
that one point of compression (1.1 ) drop my e.t. from high 14's to 13.90's and gave me like 8 more mph thru the traps, a week or so later I pulled the same heads off being so happy I finally hit the 13's for the first time ever and did a home port job on them and went back to the track and ran 13.6 at over 104 mph another 5 mph gain, a new recorded for me and it just snow balled from there. in just a matter of a couple of weeks my car went from high 14's /low 15's to mid 13's over 13 mph faster all because of some 200 dollar heads that bumped my compression up one point and me doing a little porting.
I rebuilt the same engine a few months after my new found power and threw out those cheap azz pistons and put in some 11 to 1 dome pistons and ran the same closed chambered heads having 11.8 to 1 compression and ran a huge 262/273 @ .050" cam and ran mid 12's at 110 mph.
Compression was everything, and when I changed the heads for the first time you could hear the engine thump harder, the idle and throttle response was crisper and just gave the engine a new sound.
I resisted for years, wanting to take the heads off, I tried everything else, it didn't work, I should have listened and did the heads first time around like my mentor told me, he was right all along , my compression was just to low. the cheapest thing I did 200 dollar used heads gave me the biggest performance gain then all the thousand of dollars combined.
Tried dry and wet test, same results. Car runs like a turd
