THANKS for referencing / sharing this article, Joey. Interesting! Appreciate the info.








NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Fairly interesting article here:

http://www.fordmuscle.com/archives/2000/03/timing/

Yes, it is a 1957 or later distributor. Your answers make sense, I'll re check it with the vacuum advance plugged at the carb. Might need to road test it after with someone else in the car, with better hearing. Thanks

Paul

Maximum timing recommendations hinge around what happens with full load and wide open throttle - so that is the method of set-up. This distributor is the later version with both centrifugal and vacuum advance I'll assume for now?

The plan is to set up the intial advance - plus the centrifugal advance - to total something like 36°-38° when the rev's are high enough to give you the full amount. No vacuum line connected during this test - plug the line to the carb and leave the port to the vacuum pot open. Mine is set at 10° initial and 26° centrifugal to total 36°. The engine speed at which full advance occurs can be lowered by using successively lighter springs in the mechanical advance mechanism - so long as you don't induce the "spark knock" you are writing about.

In low load - no load conditions spark advance can go quite high without inducing spark knock - and the increase tends to make the engine lean out and use less fuel. That is the whole intent of the vacuum advance system - economy when full load is not required.  

 
 Steve Metzger       Tucson, Arizona

Further to earlier questions about Dwell variations. With intial timing set at 8* & with vacuum connected, my timing light appears to indicate that at around 2200-2500 there is about 38-39 degrees total advance. ( I had to put additional estimated marks on the damper with soapstone, for past 30 degrees) Is this likely too much total with "C" heads on a 312 auto, using 87 octane fuel? Unfortunately, I'm somewhat hard of hearing, so if it's pinging, I'm not hearing it? Thanks.

Paul