I've wondered about this for a LONG time...
I bought a new, with the largest dial and 270 degree sweep, I could find, compression gauge to do this experiment.
I won't bore you with the fact that some surgery had to be performed to get the starter to seat properly..! If you have a Stude to GM adapter...do this BEFORE you put the engine in the car..!
Anyway, I installed the adjustable cam drive into my almost stock shortblock, with the cam in the OEM location, about 4 degree retarded.
This afternoon I was finally able to check the cylinder pressure. Now we all know how "exact" compression gauges are...right..!?
For the test , no carburetor, no spark plugs, unbroken-in rings, gauge in cylinder #1, new fresh battery.
Each test done twice.
Stock cam location (4 degrees retarded) - 156 PSI
2 degrees advanced - 158+ PSI
4 degrees advanced - 158 PSI
2 degrees retarded - 156 PSI
Basically I figured this was pretty good, since I did some chamber work in the heads and gained some cc's / dropped the static compression ratio some. To help gain a little back, .030" was removed from the head deck. I also used a set of Total Seal rings, which I figured pumped things up a tad.
But as you can see, overall moving the stock 1960 Lark, 2 barrel cam shaft around...didn't do anything to the cylinder pressure.
So...just because...the cam is now is 2 degrees advanced from stock, the drive is all back together and ready for the water pump manifold to be put back in place.
Now on to the task of wiring the whole car.
Mike