I just got these two coils on e-bay both spark good after cleaning points. but I see one has 4 screws on top other 6 our 16 has 3 coils with 6 screws. Anybody know what the 4 screw fits? Is it after market? I don't see any markings on any of the coils except the wood top is stamped ford
The four screw type is just a later version of the brass top coil used until they discontinued the brass top and went to just wood.
If you go to the encyclopedia on the home page and look at Coil Evolution all will be explained.
Hope that this helps. Bill
thanks Bill that is a very good info. I think I got it now. what I meant to say in first post our car has 3 coils with 4 screws and one wood top so I got the 4th 4 screw now it does start on it but it sparks on points bad so it needs condenser I guess. the 6 screw works good
There was a fantastic article in the Vintage Ford a few years back, and your subject is discussed in that article. All I can tell you at this point is the 6 screw is earlier, but I'm not aware of when they went to 4 screws. Maybe '16?
The four screw tops are 1916 - 1917.
Per the Model T Encyclopedia under Coil Evolution:
Removed two center holes for the vibrator base (the brass top) screws., changing the number required from six to four."