General Category > Quadrajet Carb Talk and Tips

Do Q-jets require a fuel return?

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qjetsrule:
Cliff,
Do you happen to have a picture of your plumbing at the carb you can post? Thanks

Cliff Ruggles:
Don't have any pics of it.  Pretty simply set-up.  I tap the OEM fuel filter housing for 1/4"NPT threads and install a 1/4NPT to -8 fitting.  Since everything in the rest of the system is 1/4" NPT, they get the same fittings as well. 

I use a standard $20 Holley regulator and built my own return just before it.  Nothing more than a 1/4 x 1/4 x 1/4" NPT "T" screwed directly into the bottom of the regulator.  I come out the side fitting and reduce it down for the factory return line.  The fuel takes the path of least resistance to returns to the tank constantly to take some load off the pump.

I tested the line to the carb and it will fill a gallon jug pretty quickly so no problem keeping up with my engine making over 550hp/600tq.

I'd also add that the fuel pump is very quiet once the return system was added.  It made a LOT of noise and grumbling when set up "dead head", even though Mallory says you can run them that way. 

Seems to be quite a few opinions on the Boards for this topic.  Every time you mention running a return someone jumps in and says they have been running "dead head" with a high output electric pump for nearly 50 years and zero issues anyplace. 

My pump lasted about 2 months, which included about 100 track runs and maybe 500 street miles.  Same exact pump with a new brush set still lives nearly 20 years after the return system install and dead quiet.....FWIW......Cliff

Hillbillyenginering:
Cliff
This was good info. I'm dealing with issues with my 66 toro. I was building a new fuel system and was planning it and looking for options. Plan to follow this except -6n fittings. Not racing and close to stock.

Cliff Ruggles:
Good plan as there are no negatives that I know of using a return system.  Especially for a street driven car that spends a good amount of it's time sipping small amounts of fuel while the fuel pump continues to make full cycles and move tons of fuel needed for hard runs.

Why not return the unused fuel to the tank to keep it cool and take some load off the pump?

I've never had the first issue once with my return system, but as mentioned above running "dead head" quickly fried my high volume electric pump.......Cliff

55 Tony:
Cliff mentioned to "keep it cool", that is exactly why I run mine with a return.  My return is using a fuel filter (I think for a jeep) that is made to let vapor go out the return first.  I used to have major problems with sort of vapor lock on hot days and this helped immensely.  Don't skimp on the return line, make it at least as big as the feed from the tank.  I still have some problems when the gas stations change over to winter fuel and we have a hot day, but that is the exception.  My setup works with a high volume mechanical fuel pump.

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