Tach Conversion: Mechanical to Electronic

[LarryN]

I want to convert the mechanical tach in my Series II to an electronic unit, keeping the same housing. OK - I don't really want to do this, but the distributor is wearing out, I'm having zero luck getting it rebuilt, and the Flamethrower replacement won't drive my mechanical tach. The car has been converted to negative ground.

Has anybody done this? I could use some suggestions on where to get parts and how to proceed.

Thanks

 

[RootesRacer]

The dizzy doesnt drive the tach cable, and the tach drive on the early cars is separate from the distributor.
The lucas 25D dizzy drops into the tach adapter so no reason your flamethrower dizzy shouldnt fit and work.

 

[Tom H]

Keeping it mechanical seems a good solution. But if you want to convert to electronic I assume you want to keep the old case (and dial) so as to keep using the indicators that are on the dial. If that's the case I think it might be possible. I investigated several ways to do this a few years ago. I came up with a couple options. One option involved switching the indicators to LEDs. If intersted, I will look back in what I saw as possibilities. I have an old series speedo that I used as a stand in for the lamp arrangements on the tach.



Tom H

 

[jumpinjan]

... Flamethrower replacement won't drive my mechanical tach.

As RootesRace pointed out, it WILL work, but you need to swap the drive dog to the shaft of the new dizzy. The SeriesII should be a gear hobbed on the drive dog to drive the tach cable gear in the dizzy.
Jan

 

[LarryN]

Thanks - I have looked at that distributor many times and never realized the drive unit is separate (that includes looking at a spare assembly that isn't in the car). Of course, now I have to figure out whether it is the distributor or the tach drive which is wearing out but that shouldn't be too big a problem.

A second (and sort of related) question: I replaced the tach cable to see if that was the problem. The replacement cable was too big for the drive adaptor so I had to grind it to fit. It seemed odd that the SUnbeam Specialties part wouldn't fit, but now I'm wondering if there are different drive units out there?