Great writeup on Dynamic Compression
Seems so fundamental. Install cam, check cylinder pressure.
Does not seem to be standard protocol. Am I missing something?
One issue is the procedure used for checking the cranking pressure. Some guys do it cold, some hot (should be as hot as you can get it) some guys leave the plugs in, some take them all out, some guys open the throttle wide open, some guys don't.
Then you have other issues. Like battery voltage. Condition of the starter. How good are the battery cables? Some starters spin faster than others.
I was having some issues at one time and the question came up about cranking pressure. At that time, I was starting the engine on 24 volts. With the plugs in it sounded like it didn't have plugs in it.
So I had to make it spin on 12 volts to give him an accurate number...something that would make sense.
Had I sent him numbers from cranking at 24 volts, he might have lost his mind.
That was back in the late 1980's and it was a Crower cam. IIRC I had 235 pounds of cranking pressure at 12 volts. At 24 volts it was 260ish IIRC.
The guy at Crower wanted me to put the cam in straight up, but I was already close on P/V on the exhaust side. Rolling it back 4 degrees would have put me danger close on P/V. One mishap and I'd have been smacking the exhaust valves off the piston.
That's some of the reasons why guys don't always check cranking pressure.
