The point plates are different and also the amount of advance that is built into them. You can physically fit a model J point plate into a Speedster timer but even tho it will provide spark, it won’t be at the right time, especially if you make the mistake of putting the J flywheel onto the Speedster crank. The motor may start but never runs smooth enough to rev up. The handle section of the timers are different, the model J timer has a shorter stubbier paddle section with a noticeable hump in it, where the Speedster timer handle is more of a flat blade and sticks out a bit further from the timer body.
Hope this helps.
Best
PM T2
He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...
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