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I have multiple posts on this forum trying to keep the questions separate. My next question is: I fully understand how the dwell/tach works on a Neg ground system but because I have three Packard's I would like to find a dwell/tach that I can use on the 6V, Pos ground systems. I would like to use currently made equip that members of this forum have possibly found that work. If not, what do you recommend? I've been on ebay but the descriptions and the subsequent answers to my questions tells me that the sellers don't know if the equip will work on the Pos ground systems. Thanks again.
Steve......

My dwell/tach could care less about positive or negative ground, you just reverse the leads accordingly. But of course you must have a unit designed for 6-volt to use it on 6-volt cars.

Hello Owen,
can you give me the name, make, model of your dwell/tach? Is it newer equip or from "back in the days"

I don't think that will do you much good, it's at least a half-century old. It's an Accu-something. Others will come along and correct me if I'm wrong, but I don't think any dwell/tach thats made to work with 6 volts gives a hoot about positive or negative ground as long as you put the red clip to positive and the black to negative. That said, I've never had occasion to use it on a 6-volt negative ground car.

EDIT - just looked at the unit, Accu-Chek. Only two switches on it, dwell or tach (2 ranges), and 4,6 or 8 cylinders. Use the 4-cylinder setting for the 33-34 NorthEast systems, and check each set of points separately.

I too have an old Tach/Dwell meter that I bought back in the 80's It's a Penske model 244.21013 that I bought from Sears. It doesn't care about voltage or polarity (just switch the leads). It has high and low range RPM. I haven't checked to see if the dwell works on my 38 but the Tach part works. I originally got it to work on my 81 RX7 because the Penske unit had a provision for a rotary engine. The thing is the size of a loaf of bread

I use a garden variety 12v "-' ground hot rod type tach on 6v systems as well as 12v systems for diagnostics. Haven't tried on my + ground 6v Continental engine yet.

As for the dwell meter they are great for quick points diagnostics but simply not needed nor convenient for actual point gap setting. Use a feeler gauge to set the points. THEN CHECK it with the dwell meter. If the dwell meter shows incorrect dwell then most likely the meter is faulty.

Hi PackardV8.....Thanks for the information and sharing your knowledge.

Steve......

Hi Phils38cpe, I appreciate you sharing your knowledge and experience with me.

Regards, Steve.........