A long duration cam tends to actually bleed off cylinder pressure.
I have read that a rough guideline for the pump gas limits are 200-230 psi cranking pressure.
When I built the 440/493, I advanced the '509 cam by 4 degrees. It had cranking numbers in the 230 range. Later when I returned the cam to a straight up position, it was down in the 190s. The advanced position closed the valves earlier in the cycle, so MORE pressure was evident.

Last edited by Frankenduster; 03/09/11 04:04 AM.