And - Check out Vince Falter's page on Distributor Advance.
The Model A has more capability for advance than is actually necessary for optimal operation.
Mostly Model B discussion but check out
http://www.fordgarage.com/pages/bdistributoradvance.htm
Quote:
|
The Model A ignition uses a zero crankshaft degree (TDC) initial timing point so that the engine can be easily started by hand crank, however it should never be run under load in this "retarded" position. The advance lever should always be advanced 1/3 to 1/2 travel (13 to 20 crankshaft degrees BTDC) on the steering column quadrant after starting the engine, and should generally not be run more than 3/4 advanced on the column under any normal circumstances. (Bolding mine)
|
That said with high compression heads much in demand one might not want to stretch the upper limit per the same article and with valid reason.
Quote:
|
The Model B is a higher compression (cylinder pressure) engine which uses more initial spark advance, and lower maximum advance compared to a Model A. This is consistent with the operation of the B engine and the need to protect it from the effects of running too far retarded or over-advanced.
|
More discussion of Model A versus Model B timing below including reference to a video.
http://www.fordgarage.com/pages/timingiseverything.htm
Vince is among the most cogent of sources.
Joe K