Second fuel pump to return gas to tank from carb fuel bowl

[dladow]

I was reading David Vizard's book on building & modifying carbs and manifolds, and in discussing the importance of delivering cool fuel to the carb, he mentioned installing a "smaller capacity pump" connected to the carb fuel bowl to constantly return fuel to the tank, which would act as a heat sink and help keep the fuel cooler which equals more power and no vapor lock.

 

The 1973 240z already has a return fuel line, but Vizard gives no clue as to how to set this up. Has anybody out there tried this?

 

I am planning on swapping in a carb'd SBC V8, probably using a Q-Jet.

 

Dave

[dladow]

I did some looking around at the Chevy Talk forum and its seems that the return line is generally routed through the pressure regulater, not from the carb. So you just buy a pressure regulator set up for a return line. Seems simple enough.

 

I didn't see any references to installing an additional pump connected directly to the carb bowl, which is what Vizard seems to be suggesting. Anybody ever done anything like that?

 

Here's a link to a site explaining fuel system design, - a grumpyvette find.

 

http://www.centuryperformance.com/fuel.asp

 

Dave

[COZY Z COLE]

 

This is my set-up using a MALLORY 3 port race/comp. adj. fuel reg. with return line from reg. to the fuel tank. Also vacuum reference line to a HOLLEY dp carb.

 

 

 

LARRY

[dladow]

Thanks, Larry - what a nice install. I remember seeing it at the HybridZ meet in California this spring. I think I'll end up with a similar set-up, although it will probably be overkill since I am only doing a mild budget build-up with a Q-jet carb and no sc or tc.

 

Did you redo your whole fuel system or use the existing fuel lines? I think mine are in pretty good shape, as is the gas tank, so unless I need bigger lines, I would like to use what's there.

 

Dave

[COZY Z COLE]

THANKS for the comments and I remember seeing you in RIO VISTA,CA. last year. I replaced all the lines and the fuel pump while I was at it. Looks like custom headers are next for me but I'm concerned about the additional power with my "skinny" tires on it. I have a R-230 diff. from a 91 300ZXTT and shafts from a Q45 at my house waiting for something to break in the rear of my car. Good Luck with your project and keep us posted and ask any questions!!

 

 

LARRY