MTFCA Forum

I have had a 27 T for over 50 years. When we first got the car, I noticed that it would run noticeably smoother and have more power when switched over to mag. Over the years, everything on the car has been rebuilt-motor, trans, electrical system, etc. At some point it started running as well on battery as it does on mag. Is this normal for a car in "good tune". I have always assumed that the higher voltage produced by the mag was compensating for deficiencies in the electrical system, compression, etc. and that once those were brought up to par, the extra voltage would make no noticeable improvement. Is this correct? By the way, if it's make any difference, I am still running the original vaporizer.

It has been my experience that they run better on magneto. First thing to check is magneto output. If that is low, you need to repair the magneto. If output is OK, next thing is to check the coils. If the engine is running smoothly, I would think the timer is OK.

This is what happens to an engine which has been run for many miles. The thrust surface of the rear main bearing gets worn. This wear is usually in the direction which would move the flywheel to the rear which increases the gap between the magnets and the magneto coil ring. This will lower the output of the magneto and as it increases, you might even notice that the mag will not function at idle but will work at higher speeds.
Anyway, you can read other posts about magneto and how to check the output and how to charge in the car.
Norm

Hi, David. By chance have you switched to a 12 volt battery? I use a 12 volt in my 26 and can't tell any difference between battery or magneto. With a 6 volt most T Models will run better on magneto. Bob

Still 6 volt. Field coil was new a few years ago and rebuilt coils from Ron Patterson. Car seems to run as well on battery as it ever did on magneto. As I mentioned in my original post, performance was originally better on mag than battery. It used to feel like it was holding back on battery and would surge (a relative term with a T) ahead when switched to mag. No issues now with performance, just curious.

If there is sufficient timing advance, a decent timer, and coils properly set up (equal dwell time to fire works well) 6V operation is fine.
Two of the other T's that I drive, belonging to friends, are also 6V but have working magnetos. I set up their ignition systems also, but just out of habit forget to use the magneto. Again, they run fine and don't find them lacking in high speed performance.
An "ordinary" non-rebuilt ignition system with randmonly adjusted coils with original capacitors, lots of play in the timer linkage, and a questionable timer, well yes, that will need 12V or magneto to get tolerable performance. That's in km/h (72km/h = 45mph).