Packard Forum Index » V-8 (1955-56)

Stupid question, what would happen if you wired the fuel gauge up backwards?

I haven't tried it but don't think it would matter. There are only two terminals, neither marked, and a coil of heater wire wrapped around the bimetallic element between them.

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How much did they notch the frame??? Pic if convenient.

It is a hose connection from the filler neck to the tank. I'll have to get a new hose because I destroyed the old one trying to get the tank out.

HH56- nice call on the resistor. $2 is well spent to save the factory gauge. I'll pick one up and snap some pictures of the gauge at full and empty.

I'll get a picture of the frame notch when I jack the car back up to reinstall the tank. It should be sometime this week after I get the electrics sorted out.

Question- I'm making a new gasket for the sending unit because the only other way to get one is to buy a new sending unit. What material should I use in a gasoline environment? I've got both cork and that composite gasket sheet material.

What was the original gasket made from????? I'm guessing cork. I'd most likely use the cork unless i could verify that the composite-cork is a neoprene composite and not rubber.

HOWEVER, if the existing gasket is not torn then i'd just reuse it as long as the unit is a still agood tite fit when installed.

Take a lighter and burn the composite material. Neoprene will not burn but can melt and get runny if u get it hot enuf. Rubber will just burn and gasoline will dissolve rubber but not neoprene.

As a side note:
Be carful when makeing an changes to instrumwent cluster. I have found that they are very fragile and terminal posts can twist very easily thus ruining the gaiges.

Though fuel pump diaphrams live and work in a tougher environment than your sending unit gasket, chemical resistance tables tell us that you should move away from the neo- and isoprene-type rubbers and towards Buna or perhaps nitrile rubbers. The old classic gasket material for gasoline service was of course cork coated with shellac, but ethanol is a solvent for shellac so that's no longer a good choice. However one of the Aviation gasket pastes is rated for alcohol service so as a chemist my choices for alcohol-doped gasoline would be buna rubber first, and cork with a suitable gasket cement second.

Packard V8 brings up a good point. I'd avoid doing too much pulling and disconnecting around instruments and ign switch unless absolutely necessary. Things are a bit fragile there. Install the resistor right at tank and then it will be easy to remove if you do come up with a better setup. Still kinda curious about the Chevy sender because 31 ohm spread sounds low and that sender may not be any good.

If the gauage is reading backwards then what about bending the float ARM in the opposite direction???? OR does the resistance reading still cause a problem???

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The gasket I pulled off of it was rubber, but it was badly damaged and the holes didn't line up properly with the mounting points.

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I don't plan on getting into the gauge cluster at all. I don't want to risk any damage.

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Good to know. I plan to run non-ethanol fuel as I can still get it locally here, but there are the times when it's unavoidable to buy the corn-gas. Especially here in MN where our "all knowing" government is increasing to a 20% minimum state wide.

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I looked it up on the manufacturer's website www.spectrapremium.com and the sending unit is 0-35 ohm according to the spec sheets. I'm not sure if getting 31-32 ohms on my multimeter means that this one is going bad or if it's ok. I'm thinking that I'll stick with this one for now and try the in-line resistor as HH56 has suggested. If it isn't satisfactory with the resistor, then maybe I'll try to graft on the universal sender from JC Whitney.

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To get it to work I'd have to remove the sender and re-mount it upside down. If I go that far, I'll just try the previously mentioned universal sender for the correct Ohm range.