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Help with fuel return line, will this work? #2487828
04/25/18 03:52 PM
04/25/18 03:52 PM
Joined: Dec 2012
Posts: 282
Northeast MA
Charger446 Offline OP
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Charger446  Offline OP
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Northeast MA
I am running a Holley HP series electric pump with a regulator with no return line currently.

Last summer I had a bout of vapor lock and I want to add a return line. I suppose I could just buy a regulator that has the port for the return line but I want to see if there is less expensive alternative.

See pic below. Fuel goes from pump (near tank) through a filter then up into the regulator (red arrow). The line then gets split into the carbs as you can see. What I want to do is (see green arrow area) use an AN type T fitting there and send the return fuel via a 1/4 line back into the sending unit at the tank. Currently I have a 3/8 sending unit with the 1/4 return line nipple capped off.

Appreciate the feedback

firewallxxxx.jpg
Re: Help with fuel return line, will this work? [Re: Charger446] #2487850
04/25/18 04:46 PM
04/25/18 04:46 PM
Joined: Jul 2011
Posts: 817
Eugene, Oregon
Secret Chimp Offline
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Secret Chimp  Offline
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Eugene, Oregon
When you're doing a return system you typically place the regulator after the carb supply, before the rest of the return line. This maintains the pressure throughout the entire carb circuit.

If you look at any fuel injected car's fuel rail, you'll always find the little pressure regulator dampener at the end of the rail.

Unfortunately this requires a "return style" regulator - you can't use many types of deadhead regulators in a return-type configuration from what I understand, since they aren't designed to maintain pressure under constant circulation.

Here's an article that details the differences between the regulator types:
http://www.onallcylinders.com/2017/01/12...e-fuel-systems/


1967 Dodge Coronet Deluxe station wagon

1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
Re: Help with fuel return line, will this work? [Re: Charger446] #2487920
04/25/18 07:27 PM
04/25/18 07:27 PM
Joined: Feb 2007
Posts: 612
Nampa, ID
None2Slow Offline
mopar
None2Slow  Offline
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Nampa, ID
Not sure about your regulator, but run from the tank, to the filter and up to the carb. From there, run it from the backside of the carb to the regulator and to the tank. This will hold a steady supply of fuel in the line instead of bleeding it off. This is what the above post was referring to.

Re: Help with fuel return line, will this work? [Re: Charger446] #2488234
04/26/18 01:21 PM
04/26/18 01:21 PM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
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jbc426  Offline
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I run a return type regulator on my '70 with carbs.

It bleeds of both from the high pressure side and the regulated low pressure side of the regulator. It's basically a controlled leak to the fuel tank through two separate hoses that each have a restricting jet in the line. The hoses join together after the jet and flow back to the tank in one line.

You can plumb your system the way you described with your dead head regulator, but you will probably want to restrict that flow back to the tank. Otherwise you fuel pump will be running at near full capacity to maintain pressure. Once your carbs are wide open, you may not have enough flow to keep up with a 1/4" hole in your low pressure side.

You can also run one of those 3 nipple fuel filters that come with a metered third nipple.

Insulating your fuel lines around your engine and exhaust can also help keep your fuel cooler.

Bypass Reg.gif

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Help with fuel return line, will this work? [Re: jbc426] #2488260
04/26/18 02:04 PM
04/26/18 02:04 PM
Joined: Dec 2012
Posts: 282
Northeast MA
Charger446 Offline OP
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Charger446  Offline OP
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Northeast MA
Thank you for the replies guys, great information to digest. I am still leaning towards a simple solution, I definitely will be wrapping the fuel lines. I had this set up before in my car w/o issues but I was running a glass hood with a tall scoop so there was plenty of air coming in that area but now I have a steel hood w/o the scoop.


JBC426, do you know of a supplier of the filter with the metered nipple? I thought they were just 1/4.

https://www.youtube.com/watch?v=YUmaAQoHggM

I kind of like this guy's idea, thinking I can adapt that with AN fittings and some sort of metering "jet" to get me to the .060 return size, I think the stock Mopar vapor separators calls for that? I could definitely be wrong here though.

Last edited by Charger446; 04/26/18 03:44 PM.
Re: Help with fuel return line, will this work? [Re: Charger446] #2489017
04/28/18 11:57 AM
04/28/18 11:57 AM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
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jbc426  Offline
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West Coast, USA
I've seen the 3 nipple Fram fuel filters hanging on the wall with the rest of the fuel filters at local auto parts stores.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Help with fuel return line, will this work? [Re: Charger446] #2489945
04/30/18 01:26 PM
04/30/18 01:26 PM
Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar Offline
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451Mopar  Offline
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Aurora, Colorado
Return style regulator would be the best solution as it will by-pass any fuel not needed by the engine keeping fuel circulating through the lines cooling them. This would require a large return line.

Before spending the money to convert to by-pass regulator, I would try connecting a line with a small restriction in it back to the 1/4" vapor line. This will by-pass a small amount of fuel.
On my 360 engine, I screwed a Holley Jet into the inside part of a -6 AN fitting as the restriction and made that my return hose. Just mark the line/fitting so you remember that it has a restriction in it.

Re: Help with fuel return line, will this work? [Re: 451Mopar] #2490100
04/30/18 07:07 PM
04/30/18 07:07 PM
Joined: Sep 2007
Posts: 145
NJ
C
cb1289 Offline
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cb1289  Offline
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NJ
A simple vapor return line like what you want to do works great at eliminating vapor lock. The line must be restricted as mentioned. How you plumb it is your business but it works great. I did the same system on a 65 Satellite 413 with dual quads and the throttle response was crisp like fuel injection with my vapor lock issues a thing of the past. That was in the 1990's and the same system is still working great today on the same car. This is basically the same thing the factory did in the 80's to combat vapor lock with the fuel filters with the 3 nipples. R. Eherenberg did an article many years ago in Mopar Action describing this same cure for vapor lock. Good luck.

Last edited by cb1289; 04/30/18 07:09 PM.

62 Dodge Dart Wagon 65 Plymouth Satellite
Re: Help with fuel return line, will this work? [Re: cb1289] #2490516
05/01/18 04:07 PM
05/01/18 04:07 PM
Joined: Dec 2012
Posts: 282
Northeast MA
Charger446 Offline OP
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Charger446  Offline OP
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Northeast MA
Thank you guys!


I was going to try to stay with using AN fittings so the 3 prong filter may not be the way to go for me, but I like the holley jet idea, what size did you use?

Last edited by Charger446; 05/01/18 05:37 PM.
Re: Help with fuel return line, will this work? [Re: Charger446] #2491342
05/03/18 09:54 AM
05/03/18 09:54 AM
Joined: Dec 2012
Posts: 282
Northeast MA
Charger446 Offline OP
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Charger446  Offline OP
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Northeast MA
I went through my spare fuel lines and fittings and I think I have a rough idea of how I want to plumb this.

I have read that folks use Holley Jets but not sure how to get it to work with what I have. Anyone know what size Jet? I am trying to get to about .050 for the reducer hole.

The Jet sits on the end of the male fitting and I can tighten the other fitting on top of it but it seems like it will leak like this. Thanks for your help guys.

timmyrail2.jpgtimmyrail1.jpg
Re: Help with fuel return line, will this work? [Re: Charger446] #2491352
05/03/18 10:16 AM
05/03/18 10:16 AM
Joined: Dec 2012
Posts: 282
Northeast MA
Charger446 Offline OP
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Charger446  Offline OP
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Northeast MA
Sorry 1 more pic. I think I can get the Jet to fit in one of these fittings as pictured, but based on my set up, I think the regulator is too far away from the carbs to be effective?

It would be cleaner to just run a line to the unused port of my regulator (with restrictor installed) but as I said, is that too far away to help with fuel circulation?

regulatortim.png






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