Bartamos, I do remember posting something about this issue back then, but I’d have to go back and see exactly what it was. The truck with the 350 you’re referring to is also a 1950, but it’s panel truck that’s kind of a resto mod. I do remember asking questions about that one as well, but again the details escape me. Like you said I think it was about using the stock ammeter with a GM alternator, which has worked great since 2019 or whenever it was I finished that project. I still drive that quite a bit to this day.
This issue with the fuel gauge is a few years old, and I only asked about it because I saw the pertronix unit collecting dus on my shelf, and thought I’d resurrect it and see what I could figure out this time around. Like I mentioned, I’ve been driving this truck (restored one) for a few years now with points, and negative ground. I have no issues doing that. I just figured since I have the pertronix, why not try to utilize it? The fuel gauge was the only thing preventing me from doing that. I did try to sell the pertronix for a bit, I think I had it listed on this site and oldgmctrucks, but it never sold. So it sat on my shelf. That brings us to today.
The fuel gauge will only work with negative ground, and the pertronix will only work with positive ground, so it’s one or the other. I just thought I’d throw up a post and ask for some advice again, and see if I could get any new information. It really doesn’t bother me to run the truck with either ground set up. If I can make everything work together, great. If not, the pertronix will continue to sit on my shelf, and I’m out the $150 or whatever it cost me years ago.
When I first explored this years ago, I thought exactly like you did, that the polarity would not affect the fuel gauge. And I kept being told that on the forums. However, the practical side of this was not working on my work bench, as I purchased two fuel gauges from two different vendors, who both told me they should work. But they didn’t. That’s when called Steve at the Filling Station, and was great as far as wanting to get to the bottom of this for me, so he called his supplier/vendor for the new gauges he sold, and was told that in fact these new gauges do need the correct polarity in order to work, which is of course negative ground.
I figured maybe I’ll get to the bottom of it this time around. And maybe help someone out in the process who might be having the same issues I’m having.
