Bill A

Motor rebuild supplier said this grind requires 36 degrees of initial ignition timing. Add 12d of vac and 8d more in mechical equal 50+ of total timing. I'm not buying it. Ignition timing should be a function of crankshaft angle. This motor will not run with any less timing. I had to re-stab the distributor to accomadate this. The rotor is not even close to pointing at #1. Truck was on the road for about a month in this configuation. A hole in the oil pan (wrong pan) has it parked in the driveway. I've pulled the timing cover to review the chain alignment. Crank spocket was no mark but with cyl #1 at DTC the cam spocket mark is straight up. So.. can the cam grind be right? Is the distributor wrong? Any idea why this motor is different than other chevy sb? Thanks.

71Nova

With the vac advance plugged off your total timing @3000 or above will be 36 degrees total timing.This is what you will set with motor above 3000 rpm and then your initial timing will be whatever your dist. goes back to. Unless you know how to adjust total amount of mech. advance with diff bushings just leave this alone. Once that is done and you hook the vac. advance back up it will do its thing at idle and part throttle and is possible to get 50+ total timing but at wide open throtle with no vac. you will be back to 36 degrees.