In Reply to: Re: Setting timing posted by K.LaRue-VA on October 21, 2018 at 12:34:13:
Just to be clear I do not disagree with your conclusion - just question the acuracy and reliability of the measurement procedure. The same goes for Dave Smith's modifications. It is hard to discriminate the small values neede to accurately gauge the result. What I do know is the Ford documentation is quite clear on this and can be found in a number of different publications:
The spark advance for the engine is also given numerous places as:
4° BTDC @ 400-500 RPM
This is 100% consistent - at 400 RPM the centrifugal mechanism in the 9N-12100 distributor advances the spark 4° from it's static (0 RPM) setting of 0°.
If the static setting is 4° AND the 400 RPM setting is also 4° then we have to assume the centrifugal advance mechanism in the 9N12100 distributor is inoperable between 0 and 400 RPM. Conceivable but given the documentation it seems more likely the manual is correct and the advance is linear throughout the RPM range.