Return line?

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Re: Return line?

Postby Ishiftem » Fri Sep 23, 2011 8:46 pm

cjbiagi wrote:With the simple system I have the return is regulated by a very small orifice built into the fuel filter. I don't know the size but as I mentioned this is a filter for a early 80's Chrysler "K" car which was carburated. I'm guessing the orifice is maybe .030 - .040 or something like that.........you get the idea. This is combined with the stock V8 in tank pump. As mentioned I have been running this for over 30 years and I originally did it to cure a vapor lock symptom on very hot days. I use the original vapor line as my return.


That is such a small hole and being it is before the carb, I really don't see it as having any real impact. Especially not for a mild motor on radials. We ran 11.60 with our bypass system before changing it over. Obviously it ran good, but just not to its fullest potential.
Any one can restore a car but, it takes a real man to cut one up.
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Re: Return line?

Postby Rickracer » Sat Sep 24, 2011 8:53 am

I think we may be talking apples and oranges here. I know there are literally hundreds of (street driven) V8 S10s out there, running the OEM TBI in-tank pump, with OEM 3/8" feed and 5/16" return lines, and the Holley 12-803BP regulators. Those who use inline Holley pumps or mechanical pumps often experience vapor lock and/or other fuel delivery problems, and switching back to the OEM supply system with the BP regulator cures all of them. Back when I was running my 427 Vega, I put a 1/2 pickup near the back of the stock tank, and ran a Holley Blue pump, and sometimes had vapor lock problems, since I was street racing a lot, vapor lock cost me $$$ just about every time. :? 8)

BTW, the type system I'm talking about is also on my DD 363ci roller cam, Vortec head S10, and it's been flawless for over 6 months now. 8)
Rickracer
ASE Master Auto Technician, 36+ years
'76 Vega Notchback, Twin Turbo 355/TH350 (soon to be a Powerglide w/Brake), 4 link, Koni Coilovers, 3.50 geared 9" w/Spool & Moser Axles, drag only, best all motor 1/8 mile pass to date, 6.90@99mph, 6.57@107.0 on a 60 shot, Best 1/4, 9.66@139.78, still tuning...
Project Album: http://s68.photobucket.com/albums/i4/Ri ... 20Begins/'
93 S10 RCSB, Hyd. Roller Vortec head 363 ci SBC, 2800stall lockup 700R4, LS Front Brakes, Narrowed F*rd Exploder 8.8 disc brake 3.73 posi rear, 8.0s@89 mph, (all motor, haven't sprayed it yet...)and tows the Vega to the track too
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1976 Chevrolet Vega

Re: Return line?

Postby Ishiftem » Sat Sep 24, 2011 6:51 pm

Do you have the bp regulator before the carb or after? I do not know if that makes difference but I saw on Holleys sight they had both ways of running it.We had ours after and that was the problem because it only kept as much pressure in the entire supply line as the regulator was set to. Maybe having it before the carbs would eliminate that and keep as much pressure in the line as the pump puts out up to the regulator?

As for the return, even the holley sight says to use the same return size as supply.Maybe the stock pump doesn't have enough volume to make a difference? Which is how you can get away with the 5/16?

As a side note, Holley tech support is a joke. We called looking for specs on our pump and was told our problem was we didn't have performance carburetors. Really? Told him we know multiple people running low 9s with edelbrock and carter carburetors. Still insisted we didn't have performance carburetors. :rolleyes: What a joke.
Any one can restore a car but, it takes a real man to cut one up.
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Re: Return line?

Postby Rickracer » Sat Sep 24, 2011 9:06 pm

This was just the mock-up, but it's the only good pics I've got of the setup, it's got the two steel inverted flare lines going to and from the regulator, and the braided going to the carb...I wanted to be legal to race anywhere, 8)

Image

Image

Image

Sounds like the way you had it set up, the system flowed more than the pump could supply, :? :? 8)
I'm not sure what the volume is that the stock TBI pump can move, but it's capable of 20+ psi deadheaded. 8)
Rickracer
ASE Master Auto Technician, 36+ years
'76 Vega Notchback, Twin Turbo 355/TH350 (soon to be a Powerglide w/Brake), 4 link, Koni Coilovers, 3.50 geared 9" w/Spool & Moser Axles, drag only, best all motor 1/8 mile pass to date, 6.90@99mph, 6.57@107.0 on a 60 shot, Best 1/4, 9.66@139.78, still tuning...
Project Album: http://s68.photobucket.com/albums/i4/Ri ... 20Begins/'
93 S10 RCSB, Hyd. Roller Vortec head 363 ci SBC, 2800stall lockup 700R4, LS Front Brakes, Narrowed F*rd Exploder 8.8 disc brake 3.73 posi rear, 8.0s@89 mph, (all motor, haven't sprayed it yet...)and tows the Vega to the track too
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Rickracer
 
Posts: 882
Joined: Mon Nov 30, 2009 9:11 am
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1976 Chevrolet Vega

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