Thread: 500 Caddy/G Body Swap

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A few fittings and I had it set up to run the line back to the tank.

The real key to making this work is to restrict the fuel in the return line so that the fuel pressure remains high enough to feed the carburetor but passes enough fuel to prevent the fuel from staying in heated areas too long to vapor lock. I’ve had good luck using a restrictor with a 7/64” hole in the past so this is going to be my starting point.

What I did was to tap the inside of the of the 1/4" pipe used to connect the two 90 degree fitting for 1/8” pipe thread. I then took a recessed 1/8” pipe plug and drilled the 7/64” hole thru the center of it and screwed it into the threads on the inside of the pipe. If I have to fine tune it with a bigger or smaller hole, the recessed hex on the plug makes it easy to remove and replace.

As it stands right now, I’m planning on running a new 3/8” fuel line from the tank to the fuel pump as the Cadillac engine has the pump on the driver’s side instead of the passenger side as the El Camino is currently set up for. I’ll probably use the existing 5/16” fuel line that used to be the supply line as the return line and route it to the vent fitting in the sending unit. A vented gas cap should be the only other thing I’ll need.