Got around to fixing the gas gauge issue today. I ended up ordering a new Spectra GM203 tank, straps, and sending unit. Since no one makes the sending unit for the 1974 and 75 Camaros and Firebirds. I ended up ordering a Spectra FG103C sending unit which is listed for the 1976 and newer cars (not for the 1974 and 75s, which no one makes). I ordered the tank from Advanceautoparts and used a 40% coupon so the tank only ended up costing $100 with free shipping.
You have to specifically know what you are looking for and what your car has. It seems that some of the Camaros and Firebirds used two vent lines on the passenger side and ran the main 3/8 fuel line on the driver's side (Gramma's car). The aftermarket manufacturers don't want to hear that. Most of the major fuel/brake line repro houses sell the unit that has one vent and one fuel line on the passenger side. So I ordered two different sending units and sent the incorrect one back.
It turns out that the Spectra FG103C is nearly identical to the 1975 sender, other than an extra 3" and a 90 degree bend at the end. All I had to do to make it work was cut the last 3" off and flare the line and I was all set to go.
I am glad I ended up ordering all the extras and not just the sending unit. One of the straps was corroded and broke at the bend point when I went to remove it. And the tank has a bad design in that it routes the 3/8" fuel line in the inset area alongside the outer flange, behind the tank. This inset area retains around a 1/2" of crud which corrodes the line after 40 years or so.
The old tank:
The old sending unit compared to the new one installed in the new tank. You can see the final bend in the new one that needed to be trimmed off. The copper line that is soldered in the top of the new tank needed to be connected to the vent line that I trimmed off the old tank. Two inches of 1/4" hose and a couple of clamps worked fine.
I did check the old sending unit once I removed it from the old tank. It would read properly at around 1/4 tank level but once you moved the float up, it would short out and spin the indicator needle off the guage. The new one worked fine - I made sure I tested it in the car before installing it. (once bitten twice shy...) [img]<<GRAEMLIN_URL>>/rolleyes.gif[/img]