The Stovebolt Site Forums The Shop Area General Truck Talk gas gauge ohms?

I have a 12v gas gauge from chevyduty for my 1951 3100 and a 1967 Mustang after market tank with sending unit.

When my tank is full the gauge reads 1/2 full. When the tank is 3/4 full the guage reads full and when the tank is half full or less the gauge read way over full, in fack so full that the needle is buried.

I think that this is an ohm problem. Does anyone have any sugestions for me?

well for sure they have to match,, need to make sure the sending unit and gauge are matched, I installed a stewart warner in my 52, they gave me the wrong gauge to match the sending unit,, show half full when full, got the correct one and all is fine, good luck,,,Fred

Yes the ohms are different for the older Chevys vs the ferds. I saw on one thread in the past where the person took the resistor portion of the sending unit off the chevy and put it on the Ferd pick up tube assy. He had to mess with the float rod to give full movement to it. That is the only way to do it. If I remember right the Chevy unit in 0-30 ohms and the ferd is something like 30-90ohms.
You do have to match the sender's resistance to the gauge's full vs empty etc.

I did the Mustang tank thing on my 51 Chevy truck. I ended up using the stock pickup but flipped the sender upside down (remove and reweld it). You will also have to solder in some resistors between ground and your sender wire to calibrate to the Chevy gage because the #ord sender is 70-10 (now 10-70 after being inverted) and your gage is 0-30. Only problem is that it isn't accurate at empty. Mine works pretty good until about 1/8, then it can't be trusted; time to fill er up anyway. Let me know if you are interested and I can give you the details. I think a better choice would be to get your hands on a chevy sender and figure out how to attach it to the #ord pickup.
good luck

If the 12 volt replacement for the 51 is 0-30 omhs is that the same for a 56 Chevy PU? Don't mean to hijack but if anyone knows, thanks. Steve

Yep, the '56 Chev pickup is 0-30 OHMS. Least mine is.

Thanks for the replies.

I think I have a sender still in my old tank. I'm going to try to put that one in the must$ng tank. If it doesn't work I'll pick up another one and modify it to fit the f$%ds tank

I want original gauges and don't really care if they aren't exactly acurate. My main concern is I don't want to run out of gas. So I need it to let me know when I'm getting down to a couple of gallons...

I'll post a reply of my results.

I did a sender swap in my 56 with a stang tank a while back. What I did was to clamp the stang sender to the bench and magic mark a line along the float path. Then remove the sender from the tube and replace it with the chevy unit. Play with the positioning on the tube and the float arm lenght until you mimic the origional float path. Make sure that the Chevy sender goes to the full limits and that's it. A little solder and a new ground strap and it's over. Good luck Richie Z