Engine Timing Gear Cover Recognition

[Bob Bidonde]

Relative to the location of the ignition timing pin hole, there are different front engine covers for the Model "A" & various "B" engines. These covers are similar castings except for the location of the ignition timing pin hole. When you have an unknown cover in hand, the question arises, "Is it a for a Model 'A' or one of the various Model 'B's'"?

The photo contains the timing pin hole location for a Model "A" cover. The pin hole is 1.38" center-to-center from the bolt hole that is situated just to the side & below it.
I do not have a Model "B" cover handy to measure its pin hole location. However, if someone will post the corresponding dimension for the Model "B", I will amend the photo to show it.
In the photo with the 4 covers, note the difference in timing pin hole locations between the Model "A" & Model "B" covers. The pin hole location in the Model "B" covers is 9.5 Camshaft Degrees above the location of the Model "A's" timing pin location. Why is there a difference? Because unlike the Model "A", the Model "B" distributor has an automatic spark advance system.