Engine: INSTALLING TACHOMETER IN A 6 CYLINDER 6 VOLT Stude

[Nanaimo guy]

I would like to install a tachometer in my 51 Studebaker so I can change gears at correct rpm. 1st problem..6 volt tachs are over $500 and they would be positive ground.
You can pick up a 12 volt tach for $50 with 4-6-8 settings. My car has a second 12 volt battery to operate my 62 Studebaker transistor radio. I could hook up tach positive and
ground wires directly to the 12 volt battery. Now where on the coil does the green tach wire go with positive ground 6 volt system. Would it even work ? Isn't possible a tach
(as long the unit is insulated from car body) would work even on 6 volts with wires going directly to 6 volt battery. I wonder if they made 6 volt tachs with positive grounds in
the 50's. I have seen photos of dual carb Champion 6's. Im sure they must have had tachs too.

[gordr]

Sure, they made six volt tachs. I'd watch eBay. They have a lot under "vintage tachometers", but be advised that many of the sellers don't know what they are selling. Many Sun brand tachs need a separate sending unit, and a Sun tach without the right sender is useless. I had a '64 Daytona which had a Veglia tach in it, and that tach had NO connection to 12 volt power; it was wired in-line between the points and the coil. Such a tach would work on either six or twelve volt systems. I did see one tach in the listings that had a similar wiring scheme, so they are out there.

Just for the heck of it, I would try using the tach you have, powered by the 12 volt battery, and I would connect the green wire to the coil (+) terminal, the one that goes to the distributor, with an 0.1 uF, 400 volt mylar capacitor in series. That capacitor ought to pass the voltage pulses OK, but prevent any DC feedback through the tach that could cause the magic smoke to come out. Either it will work, or it won't, but trying it should not wreck the tach or burn your car down, and you could do it all under the hood with some clip leads if you are careful.

[TWChamp]

Model A's are also 6 volt positive ground, and many guys have used a tach called "tiny tach" IIRC. Try a google search for tiny tach and see what comes up. I'm sure they are much less than $500, probably closer to $100.