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> Recirculation circuit for -6 with carbs..
mb911
post Jan 2 2019, 01:36 PM
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I know @MarkHenry has talked about this but I want to also do this and have a few questions..

I need to buy my stainless lines for my car and my question is that I have a PMO regulator that has a return to the tank and am using Webers on my -6.. Should I be running all 4 lines from Tangerine or is there another better option?? I want this system safe..
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TravisNeff
post Jan 2 2019, 02:30 PM
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I am doing the same setup, PMO regulator and new tunnel lines from Tangerine Racing with the large supply line & small return. I am going to do regular (ethanol/FI) fuel line in the engine compartment to the regulator and fuel filter canister.
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db9146
post Jan 2 2019, 02:30 PM
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Ben,
Just curious....if carbs typically require 3 to 4 or so lbs. of pressure, are you talking about running higher pressure and letting the reg. return anything higher than required to the tank? I know you do this on a fuel inj. system, but what's the advantage to doing this with carbs?
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TravisNeff
post Jan 2 2019, 02:38 PM
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I got this 10 micron filter from Summit and ordered a spool of the smaller sized line. Will need to get the larger size line for the supply and work out the fittings.


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mb911
post Jan 2 2019, 02:40 PM
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The advantage is cooler fuel.. Less vapor locking..

How did the factory -6 use the return?
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TravisNeff
post Jan 2 2019, 02:40 PM
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Yes, you can run a FI fuel pump and will return the excess pressure to the tank. Fuel should stay cooler I guess. The better carb pumps run 7-12lbs from what I read, so it would need a regulator and return as well.
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TravisNeff
post Jan 2 2019, 03:43 PM
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http://www.914world.com/bbs2/index.php?showtopic=269922

914-6 stock fuel system discussion.

Edit: from the pic below you see that the return is right at the pump, which will be different from you pmo regulator. I would buy the 4 piece kit from Tangerine, with the 2 short lines that penetrate the engine shelf. I bought the 3 piece 914-6 kit and didn't think it through.


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dr914@autoatlanta.com
post Jan 2 2019, 03:54 PM
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I would definitely recycle the fuel to keep it cool


QUOTE(mb911 @ Jan 2 2019, 12:36 PM) *

I know @MarkHenry has talked about this but I want to also do this and have a few questions..

I need to buy my stainless lines for my car and my question is that I have a PMO regulator that has a return to the tank and am using Webers on my -6.. Should I be running all 4 lines from Tangerine or is there another better option?? I want this system safe..
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mb911
post Jan 2 2019, 04:04 PM
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QUOTE(TravisNeff @ Jan 2 2019, 01:43 PM) *

http://www.914world.com/bbs2/index.php?showtopic=269922

914-6 stock fuel system discussion.

Edit: from the pic below you see that the return is right at the pump, which will be different from you pmo regulator. I would buy the 4 piece kit from Tangerine, with the 2 short lines that penetrate the engine shelf. I bought the 3 piece 914-6 kit and didn't think it through.



@TravisNeff that's what I was thinking.
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bbrock
post Jan 2 2019, 04:44 PM
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Well I'm just running a -4 but am doing the same for my carbs. I just ordered a line kit from @Rotary'14 a couple days ago. I haven't decided on my pump and regulator yet but keeping all of the lines stock diameter and will fit with ethanol FI hoses. In addition to keeping the fuel cooler, the pump doesn't work as hard with a return line. Bonus for me is that if I ever decide to put the stock FI back on, I won't have to mess with the fuel lines again.
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GeorgeRud
post Jan 2 2019, 04:55 PM
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I took another approach and moved a Pierburg low pressure pump up front by the steering rack, and then simply ran the one fuel line back to theeng8ne compartment. As the fuel in the line is already pressurized, it’s less likely to vaporlock. However, I don’t see any downside to running a return line back to the tank.
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Krieger
post Jan 2 2019, 11:58 PM
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I was running a PMO "regulator" on my 3.0 carbed 6 with a return line. It seemed to have worked for a while, but then I realized my pressure on the gauge was anywhere from 3 to 9 psi. No amount of adjusting would drop it to stay consistently desired range. The PMO unit is not really a regulator. No spring. It is more of a flow restrictor. I ended up using a Holly low pressure regulator with no return line.
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jkb944t
post Jan 3 2019, 06:58 AM
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QUOTE(Krieger @ Jan 3 2019, 12:58 AM) *

I was running a PMO "regulator" on my 3.0 carbed 6 with a return line. It seemed to have worked for a while, but then I realized my pressure on the gauge was anywhere from 3 to 9 psi. No amount of adjusting would drop it to stay consistently desired range. The PMO unit is not really a regulator. No spring. It is more of a flow restrictor. I ended up using a Holly low pressure regulator with no return line.


What pump were you using and what pressure was it rated to put out?

Jeff B
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rgalla9146
post Jan 3 2019, 09:10 AM
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The ideal is the OEM Bosch 3 port fuel pump (009) moved to the front.
They are very expensive. I must admit I haven't done it on my original 6
It can be slow to hot start.
In my conversion I'm running a Pierburg up front with just a supply to the carbs.
No regulator but a discrete fuel pressure gauge.
I've done the PMO anti-percolation mod to the Webers and added heat insulators
below the intake manifolds.
Fingers crossed.
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Krieger
post Jan 3 2019, 09:24 AM
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I have a mallory 110 that is rated for 7psi.
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campbellcj
post Jan 3 2019, 09:46 AM
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I have been using a Holley Red 7psi pump with no return line or regulator and this setup has worked great for over a decade. It had a regulator at first but one or more of my mechanics/builders deemed it unnecessary for this car, which spends most of its time near or at WOT and at high-RPM, chugging fuel like there's no tomorrow. Maybe I will reinstall the reg and think about a return line if I put it back to streetable configuration.
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IronHillRestorations
post Jan 3 2019, 10:00 AM
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There's primarily two types of pressure regulators, blocking and bypass. Blocking you put before the carbs, and bypass goes after the carbs with a return line.
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914Toy
post Jan 3 2019, 11:00 AM
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I generally follow the strategy of "keep it simple". I have carbs on my 2.7 911 engine, with a low pressure fuel pump up front (Tangerine), pumping to a pressure regulator located just before the carbs, maintaining 3 lbs. pressure, with no return line. I have no fuel delivery problems.
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brant
post Jan 3 2019, 11:16 AM
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a return line produces cooler fuel and should produce more HP (ever so slightly)
all modern cars use a return line and even the factory used a return line



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Valy
post Jan 3 2019, 11:50 AM
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The return line keeps your fuel cool and cools down and reduces load on the fuel pump. Keep it.
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