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Hey All,
I have a 70 Judge, non-a/c car, with RA III, manual. I dropped my fuel tank to put a new sending unit in. The old unit had only 1 tube for the fuel, no vapor return line. I've read here on a forum about the non-a/c cars not having a vapor return line; but that discussion was for a 65 gto. So what is the correct answer for the 70 gtos???
I want to make sure I order the right sending unit.
thanks for you help
 

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Not sure if your particular car had it or not. Some cars did, earlier AC cars especially. AC cars got things to reduce heat because the AC condenser dumps the heat in front of the radiator and heats up everything.

So they got a fuel return line, a 4 core radiator, a seven bladed fan, a fully surround deep fan shroud all to aid cooling. Today with the gas having lower vaporization temperatures any of those improvements help your combo to run cooler.

So even if your did not have a fuel return line you could install one. It is not a vapor line by the way, it flows liquid gas, but thru a small orifice back to the tank. You would need a fuel sender with a return line, a return line and either a fuel pump with a return line or just u turn the fuel feed line at the carb feed, that is actually the coolest (temperature wise) way. I do that, but it takes more plumbing and depends on your carb set-up on whether it is easy or hard to do.

Sometimes just the return from the fuel pump is the easiest and defeats vapor lock.Fuel senders and pumps with return lines are readily available.

Maybe someone with a 70 Judge will know exactly what models may have had return lines.

Everything you do to keep fuel temps down is a good things, with the one exception of leaving the crossover open. That keeps the fuel hot in the intake where you want it to vaporize, but not before that.

above the throttle plate, you want liquid below atomization then vaporization....
 

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Not sure if your particular car had it or not. Some cars did, earlier AC cars especially. AC cars got things to reduce heat because the AC condenser dumps the heat in front of the radiator and heats up everything.

So they got a fuel return line, a 4 core radiator, a seven bladed fan, a fully surround deep fan shroud all to aid cooling. Today with the gas having lower vaporization temperatures any of those improvements help your combo to run cooler.

So even if your did not have a fuel return line you could install one. It is not a vapor line by the way, it flows liquid gas, but thru a small orifice back to the tank. You would need a fuel sender with a return line, a return line and either a fuel pump with a return line or just u turn the fuel feed line at the carb feed, that is actually the coolest (temperature wise) way. I do that, but it takes more plumbing and depends on your carb set-up on whether it is easy or hard to do.

Sometimes just the return from the fuel pump is the easiest and defeats vapor lock.Fuel senders and pumps with return lines are readily available.

Maybe someone with a 70 Judge will know exactly what models may have had return lines.

Everything you do to keep fuel temps down is a good things, with the one exception of leaving the crossover open. That keeps the fuel hot in the intake where you want it to vaporize, but not before that.

above the throttle plate, you want liquid below atomization then vaporization....
I have original 1970 Judge RA IV. It came with a 5/16 fuel return line. No a/c and 4 speed
 

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Thanks Cap good info, by 1970 I guess they had figured how important that fuel return was to prevent vapor lock, and RPM’s make and power makes heat, so it goes to reason the Ram Air Judgecwould benefit, even without AC...
 
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