[Fot] electric tach to fit TR4 tach body?

[Randall]

> My experience with the electric tach conversion in my TR4A is 
> that the tach is not very happy. I wasn't able to do careful 
> measurements but the little that I did led me to believe that 
> the voltage was likely to drop *below* the critical voltage 
> of whatever regulator is now inside the tach shell!

Very possibly, my point was just that I don't think an alternator conversion
is going to fix that; unless your alternator puts out enough at idle to keep
up with the maximum load.  Even the 60 Amp Ford alternator on my TR3A
wouldn't keep up with headlights plus radiator fan, at idle.

IOW the problem is not your charging system, it's the tach (assuming that
the wiring is sound, etc.).  Any "reasonable" car electronic device should
work down to at least 10v and up to at least 16v (and withstand pulses much
higher than that).  (If memory serves, the tractor company I work for
insists that our devices work properly from 7 volts to 30 volts, not sure
what the impulse rating is.)

BTW, Jim, you might look at a MSD tach adapter.  One of their units should
make almost any tach work with a Crane XR700.

-- Randall