fuel return line
Thread Starter
Cruising
Joined: Jun 2012
Posts: 10
Likes: 0
From: Archbold, Ohio
fuel return line
I have a 1969 corvette coupe with a mildly built 350. It has a 4sp. transmission and a Holley 750 double pumper, but I am still running the stock mechanical fuel pump. I am planning to upgrade to a 110gph Holley mechanical fuel pump and a regulator. My question is, do I need to use the fuel return line, or can this be blocked off? If I need the return line, what is the best way to do it? The pump and regulator that I bought do not have a port for a return line. Any suggestions? I don't want to screw this up. Thanks in advance.
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
See my posts and photos in the following topics:
http://forums.corvetteforum.com/c3-t...k-in-a-c3.html
(see my post #20)
http://forums.corvetteforum.com/c3-t...d-by-lars.html
Lars
http://forums.corvetteforum.com/c3-t...k-in-a-c3.html
(see my post #20)
http://forums.corvetteforum.com/c3-t...d-by-lars.html
Lars
Pro
Joined: Nov 1999
Posts: 520
Likes: 5
From: Front Range
RobbMC makes a great 1/2" supply/return style fuel sender for the C3.
While true, a 750 DP is probably overkill for your 350, an upgraded fuel system is a great upgrade to prepare for future power. I just installed a regulator with an interchangeable spring to go high pressure if I switch to FI.
I was waiting until I finish my project before posting info, but I did a full AN-8 supply/return setup with pump and regulator, which in the searching I had done, isn't well documented for the C3.
Best,
tbw
While true, a 750 DP is probably overkill for your 350, an upgraded fuel system is a great upgrade to prepare for future power. I just installed a regulator with an interchangeable spring to go high pressure if I switch to FI.
I was waiting until I finish my project before posting info, but I did a full AN-8 supply/return setup with pump and regulator, which in the searching I had done, isn't well documented for the C3.
Best,
tbw
Thread Starter
Cruising
Joined: Jun 2012
Posts: 10
Likes: 0
From: Archbold, Ohio
RobbMC makes a great 1/2" supply/return style fuel sender for the C3.
While true, a 750 DP is probably overkill for your 350, an upgraded fuel system is a great upgrade to prepare for future power. I just installed a regulator with an interchangeable spring to go high pressure if I switch to FI.
I was waiting until I finish my project before posting info, but I did a full AN-8 supply/return setup with pump and regulator, which in the searching I had done, isn't well documented for the C3.
Best,
tbw
While true, a 750 DP is probably overkill for your 350, an upgraded fuel system is a great upgrade to prepare for future power. I just installed a regulator with an interchangeable spring to go high pressure if I switch to FI.
I was waiting until I finish my project before posting info, but I did a full AN-8 supply/return setup with pump and regulator, which in the searching I had done, isn't well documented for the C3.
Best,
tbw
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Lars
Thread Starter
Cruising
Joined: Jun 2012
Posts: 10
Likes: 0
From: Archbold, Ohio
fuel return line
Thank you Lars, you are right. It is all there if I was paying attention to what I was reading. But now, I have some more questions. (imagine that) What size of line did you reduce down to, and what size is the male an fitting at the outlet of the reducer/resrictor fitting? I would like to do mine just like the one you showed and route it to the factory return line at the frame. Thank you again. bvette1000
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
Another thing to consider, is a rear mounted electric pump. I've had good luck with the Mallory 140 set up. Pump and filter at the rear tank and three port bypass regulator for return line on the engine, with dial pressure gauge. I like this on rarely driven cars, as primes the carb for quick start up's, and I switch it off, to stall out on empty carb bowls, when parking.
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Safety Car
Joined: Aug 1999
Posts: 4,862
Likes: 118
From: Texas
Another simple solution is to install a fuel filter w/ a built-in vapor return line. I have one installed about 12" before the carb and it prevents vapor lock on my big block, even when it's 100f outside.
Safety Car
Joined: Aug 1999
Posts: 4,862
Likes: 118
From: Texas
Here's a 3/8" version w/ a 1/4" vapor return barb.
http://www.napaonline.com/Catalog/Ca...041_0297054279
http://www.summitracing.com/parts/WI...n/?prefilter=0
http://www.napaonline.com/Catalog/Ca...041_0297054279
http://www.summitracing.com/parts/WI...n/?prefilter=0
Last edited by RatRacer; Jul 25, 2012 at 09:14 PM.
Pro
Joined: Nov 1999
Posts: 520
Likes: 5
From: Front Range
Please note that a vapor return is not the same as a return-style fuel regulator.
With a return style regulator, you need two large lines 1/2" or AN-8 ID running from the tank to the regulator. Fuel flows to the regulator, provides its 7psi or whatever you're running, and pushes the excess back to the tank. Recirculation keeps fuel temps down, and the pump doesn't have to work as hard as in a "deadhead" setup, where there is one large supply line and no return, or just a vapor return.
I just completed a project running two AN-8 hoses from tank to regulator in place of the stock hardlines. It can be done with the frame on with a bit of patience and using hose clamps. I'll have pictures up in the next couple weeks.
tbw
With a return style regulator, you need two large lines 1/2" or AN-8 ID running from the tank to the regulator. Fuel flows to the regulator, provides its 7psi or whatever you're running, and pushes the excess back to the tank. Recirculation keeps fuel temps down, and the pump doesn't have to work as hard as in a "deadhead" setup, where there is one large supply line and no return, or just a vapor return.
I just completed a project running two AN-8 hoses from tank to regulator in place of the stock hardlines. It can be done with the frame on with a bit of patience and using hose clamps. I'll have pictures up in the next couple weeks.
tbw
Pro
Joined: Feb 2012
Posts: 668
Likes: 21
Ratracers solution seems simple, but just to clearify - would one run the return line from the filter to the gas tank? I have never seen this set up before and wonder why. It seems like an easy fix. If I was going to do it I would have to cut the metal fuel line infront of my carb but if VL becomes a problem with my car I would do it.
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Tech Contributor
Joined: Aug 1999
Posts: 14,376
Likes: 6,375
From: At my Bar drinking and wrenching in Lafayette Colorado
Thank you Lars, you are right. It is all there if I was paying attention to what I was reading. But now, I have some more questions. (imagine that) What size of line did you reduce down to, and what size is the male an fitting at the outlet of the reducer/resrictor fitting? I would like to do mine just like the one you showed and route it to the factory return line at the frame. Thank you again. bvette1000
