[siragan]

If you run your GT up at 4K+ rpms (like... really drive it, not just drag race like the rest of the rice world), would the most power come out of advanced or retarded ignition timing?

 

[Beaverboy]

You're almost always going to get more power out of advanced timing (until detonation tears your engine apart). Distributors have a method of advancement that keeps the ignition timing a little retarded at lower RPM (so that the spark comes on around TDC) and advances as the RPM increase (sparks well before TDC) so that the majority of the burn occurs during the meaty part of the downstroke.

If timing gets advanced too far the burn will occur before TDC and then the pistons begin to be pushed backwards.

I think the advancement technique used on your EGTs is vacuum. Some vehicles use a mechanical means of advance which is preferred in engines that rev quickly where a vacuum system is too slow to keep up.

 

[siragan]

I was unaware that the BP advanced the timing at higher rpms. I know that with old muscle cars, the distributors had a mechanical "swingarm" that worked on the "centrifugal" force. It was kinda neat actually.

I don't seem to see anything on the BP engine that would advance the timing though... anybody care to explain?