Fuel lines, Return line for carbs |
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Fuel lines, Return line for carbs |
spunone |
Jun 27 2006, 06:55 PM
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#1
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
Installed some 3/8 stainless fuel lines both feed & return.Now after talking to A guy from Aeromotive return line is not big enough if I use there's or mallorys return regulators .Said line not big enough on the return and will flood carbs at Idle (IMG:style_emoticons/default/WTF.gif) Anybody have any ideas .? Besides putting in larger return Line .Thanks
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Thack |
Jun 27 2006, 07:18 PM
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#2
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
Use a small fuel pump to feed back into the gas tank?
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URY914 |
Jun 27 2006, 07:23 PM
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#3
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I built the lightest 914 in the history of mankind. Group: Members Posts: 120,693 Joined: 3-February 03 From: Jacksonville, FL Member No.: 222 Region Association: None |
Let me get this right.
You have 3/8" supply and a 3/8" return. And he says you need a bigger return?(IMG:style_emoticons/default/blink.gif) Wouldn't there be LESS gas being returned to the tank because some of it is being burnt, right? I don't use a return line, no wonder my car won't idle. (IMG:style_emoticons/default/confused24.gif) |
Thack |
Jun 27 2006, 07:27 PM
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#4
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
Why do you need a return regulator? Is the flow that strong?
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GeorgeRud |
Jun 27 2006, 07:34 PM
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#5
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Advanced Member Group: Members Posts: 3,725 Joined: 27-July 05 From: Chicagoland Member No.: 4,482 Region Association: Upper MidWest |
As long as there's a return and a fuel pressure regulator that hold the carb pressure where it should be, I can't help but think that you're just fine. If you start having trouble with float levels, then the pressure may be too high, but as long as the lines are the same size, you shouldn't have any problems. Mine are about the same on my carbed 2.7.
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lapuwali |
Jun 27 2006, 07:55 PM
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#6
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Not another one! Group: Benefactors Posts: 4,526 Joined: 1-March 04 From: San Mateo, CA Member No.: 1,743 |
Note he said their or Mallory's return regulators. It's possible they work depending on a pressure difference between the feed side and the return side, and depend on the feed side having a higher pressure than the return side. With equal sized lines, the pressure will be equal on both sides, so the regulator will either stay shut, or stay open.
Strictly a guess on my part... |
spunone |
Jun 27 2006, 09:17 PM
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#7
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
he said supply line is fine but with a return smaller than 1/2 inch you get to much back pressure (IMG:style_emoticons/default/WTF.gif) and the regulator will not operate correct at set pressure
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tat2dphreak |
Jun 27 2006, 09:24 PM
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#8
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stoya, stoya, stoya Group: Benefactors Posts: 8,797 Joined: 6-June 03 From: Wylie, TX Member No.: 792 Region Association: Southwest Region |
umm... carbs don't use a return line.. .at least none I've ever seen... and a 3lb pressure pump(which is all you should have on carbs) wouldn't create enough pressure for a return line anyway... wtf? is this something new? return lines are usually used for FI... where high pressure is sent to the system, and what ever is not used is sent back
do /6s have a return line whereas /4s(carb setup) don't? is that the difference? |
Aaron Cox |
Jun 27 2006, 09:31 PM
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#9
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
carbs DO use a return line... if you do it the UBER correct way...
fuel will end up cooler... etc..... ask brant. he posted the benefits |
brant |
Jun 27 2006, 10:16 PM
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#10
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Thanks for the introduction Aaron...
yep.. I'm the harper.. carbs do use a return line if they are done right and done for maximum HP... and heck wouldn't it be worth another 5$ to do something right and possibly better. (go to a race track and see how the top carb guys are plumbed...) regarding you fuel line dilema.. I think you'll be fine. why don't you buy a fuel pressure gauge and then "know" for certain. you can plumb the regulator either before or after and use the guage accordingly. you should be fine unless you have a Monster!!! pump on it. I've seen a 906 motor (twin plug 2.0/6L with 46 carbs) run just fine on a 15psi Holley pump with a regulator. If your pump is bigger than that I'd recommend down sizing your pump. brant |
Thack |
Jun 27 2006, 10:19 PM
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#11
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
Unless you have a monster motor, this Mallory unit sounds like it's overkill. How much hp does your motor make? Maybe this return regulator is set up for a loop style, huge carb that needs a lot of fuel. What kind of setup do you have Spunone?
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spunone |
Jun 28 2006, 07:29 AM
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#12
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
I'm going to be running a 2316 about a 185 HP not crazy big.Reason for running return cooler fuel = max hp .The pump is not huge it's the regulator that has the problem with the return line .Brant what regulator are you useing and what size return you running? Thanks all
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brant |
Jun 28 2006, 08:19 AM
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#13
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
I'm just running a holley regulator (not too impressed with it actually..)
and I'm just using the 2 sizes of brake-line down the center tunnel. what are those 2 common sizes of brake line? maybe 5/16 and ? brant |
tat2dphreak |
Jun 28 2006, 03:29 PM
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#14
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stoya, stoya, stoya Group: Benefactors Posts: 8,797 Joined: 6-June 03 From: Wylie, TX Member No.: 792 Region Association: Southwest Region |
now I'm really confused... carbs generally like warmer fuel than FI, so using the return line to cool the fuel seems counter productive..
how is the setup properly plumbed though? there's not return-out for webers that I've ever seen... as it is now: fuel line from tank ________________________________========carb 1 ________________________________|| (tank)=(pump)==============="T" ________________________________|| ________________________________========carb 2 |
spunone |
Jun 28 2006, 03:34 PM
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#15
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
Ok Wayne here ya go Tank- Filter -Pump - regulator-carbs .the return line is from the regulator so there a smooth flow at all times (IMG:style_emoticons/default/beerchug.gif) .Youcan also use another filter before the carbs
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tat2dphreak |
Jun 28 2006, 03:39 PM
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#16
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stoya, stoya, stoya Group: Benefactors Posts: 8,797 Joined: 6-June 03 From: Wylie, TX Member No.: 792 Region Association: Southwest Region |
ok, I see... my regulator is at the "T" I have filters before the "T" and before the pump... so I just need a different reg. with a return... ok, that's not bad then... still seems redundant though... the regualtor should "regulate" the flow without the return... but I see the point in it now... and it won't make the fuel cooler though... because the return is before the carbs...
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scottb |
Jun 28 2006, 04:09 PM
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#17
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who wants a PEZ?! Group: Members Posts: 1,993 Joined: 27-December 02 From: south-(not north)-wick, MA Member No.: 32 Region Association: North East States |
any one have a part number and dealer for a return regulator? i am going to have carbs on my new motor. not a monster, 2056 125hp.
cheers, scott |
brant |
Jun 28 2006, 04:30 PM
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#18
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Ok...
I finally found the old thread I wanted on the 15th page of my search: Here it is.. it actually shows a wonderfully done diagram with 6 different manners to plumb this... I agree that carbs might like some heat... when the ambiant is freezing (said sarcastically) I don't think that in the summer, and after the car has been warmed for a few minutes that heating the fuel is a problem with carbs. The modern fuels SUCK... they are MUCH more sensitive to temperature than old style fuels. in fact at as little as 100F they can start to act up and cause problems most engine bays are way over that temp in the summer. I shielded all of my fuel lines in the engine bay for just that reason brant |
spunone |
Jun 28 2006, 05:01 PM
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#19
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Senior Member Group: Members Posts: 945 Joined: 6-April 04 From: Anaheim CA Member No.: 1,901 Region Association: Southern California |
Mallory makes a nice regulator with return as does aeromotive just make sure you buy the one that can go down to 3 1/2 PSI I sure there's others out there make sure you use the right filter before the pump one that won't restrct flow (IMG:style_emoticons/default/beerchug.gif)
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Thack |
Jun 28 2006, 05:13 PM
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#20
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
I see what you mean now. Are you going to replace the return line or keep it and see what happens. Those high flow pumps really flow some fuel and it might be necessary at idle to return the fuel. I thought only huge carbs like 850cfm needed that kind of setup. Always best to go with manufacturers reccomendations.
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