3/8" fuel return line ?
#2708776
10/21/19 09:18 AM
10/21/19 09:18 AM
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Joined: Sep 2003
Posts: 19,396 north of coder
moparx
OP
"Butt Crack Bob"
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OP
"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,396
north of coder
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what happens to a 3/8" return line to the tank when it's funneled through a 1/4" tube through the sending unit ? is it enough to worry about if the sending unit return is returned to 3/8" inside the tank ? this is approximately 2" in length. i'm thinking i should just replace the 1/4" with a piece of 3/8 and be done with it. what say you guys ? TIA as always !
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Re: 3/8" fuel return line ?
[Re: moparx]
#2708785
10/21/19 09:43 AM
10/21/19 09:43 AM
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Joined: Oct 2006
Posts: 1,264 New York, USA
Chargerfan68
pro stock
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pro stock
Joined: Oct 2006
Posts: 1,264
New York, USA
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IMO, any restriction in the fuel system is a restriction. Even in the return system. I replaced my 1/4” with 1/2” to match supply.
1.50 60Ft. , 10.75@ 127MPH Hauling 3900 LBS.
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Re: 3/8" fuel return line ?
[Re: CSK]
#2708797
10/21/19 10:40 AM
10/21/19 10:40 AM
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Joined: Jun 2004
Posts: 3,380 St. Charles, MO
wingman
Uncreative Title
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Uncreative Title
Joined: Jun 2004
Posts: 3,380
St. Charles, MO
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Even a 2" section is going to reduce volume to that of a 1/4" line.
If you want to get the full benefit of the larger line the whole run needs to be that size.
1969 Dodge Coronet Super Bee 383 A4 1970 Plymouth Road Runner 440 FC7 (sold)
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Re: 3/8" fuel return line ?
[Re: moparx]
#2708823
10/21/19 11:49 AM
10/21/19 11:49 AM
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Joined: Jan 2003
Posts: 31,027 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,027
Oregon
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what happens to a 3/8" return line to the tank when it's funneled through a 1/4" tube through the sending unit ? is it enough to worry about if the sending unit return is returned to 3/8" inside the tank ? this is approximately 2" in length. i'm thinking i should just replace the 1/4" with a piece of 3/8 and be done with it. what say you guys ? TIA as always ! You tell us. Are you having an issue or not? A 1/4 inch return line will work just fine if you aren't trying to shove a ton of gas thru it. If your pump is matched to your engine then the return line shouldn't be flowing a huge amount of fuel. If the car is running now then put a pressure gauge on the return line to see if you have an issue.
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Re: 3/8" fuel return line ?
[Re: AndyF]
#2709169
10/22/19 12:29 PM
10/22/19 12:29 PM
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Joined: Sep 2003
Posts: 19,396 north of coder
moparx
OP
"Butt Crack Bob"
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OP
"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,396
north of coder
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andy, there is no issue now because this sender [and new stainless tank] is [are] not installed. i am aware this is a possible restriction, and i'm pretty sure i will just change it to a 3/8 or 1/2" size. i've done that several times in the past, so it's no big deal. i was wondering just "how much" of a restriction this "could" be. an in tank electric pump will be used. [i haven't got that far yet] i will be starting with a carb, so i'll have to regulate the flow for that, but plans include going to FI some time in the future. my car already has a 3/8" feed line, but still needs a return. at that time, prepare for a bunch more questions from this old fart. thanks for the replies so far guys !
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Re: 3/8" fuel return line ?
[Re: Mattax]
#2709478
10/23/19 11:55 AM
10/23/19 11:55 AM
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Joined: Sep 2003
Posts: 19,396 north of coder
moparx
OP
"Butt Crack Bob"
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OP
"Butt Crack Bob"
Joined: Sep 2003
Posts: 19,396
north of coder
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very interesting article ! Thank You ! the diagrams give some insight and something to consider. rigging up a test device of some sort to see what the 3/8 to 1/4 reduction would do, could give me an answer. i'll have to do a little studying and see what i have laying around in the "plumbing" department.
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Re: 3/8" fuel return line ?
[Re: moparx]
#2709507
10/23/19 12:49 PM
10/23/19 12:49 PM
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Joined: Aug 2011
Posts: 2,857 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,857
Pattison Texas
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very interesting article ! Thank You ! the diagrams give some insight and something to consider. rigging up a test device of some sort to see what the 3/8 to 1/4 reduction would do, could give me an answer. i'll have to do a little studying and see what i have laying around in the "plumbing" department. it will ALL depend on the pump volume & pressure setting you want, a lower pressure will need a larger return with a high volume pump
Last edited by csk; 10/23/19 01:02 PM.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 3/8" fuel return line ?
[Re: hemienvy]
#2709635
10/23/19 07:49 PM
10/23/19 07:49 PM
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Joined: Aug 2011
Posts: 2,857 Pattison Texas
CSK
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master
Joined: Aug 2011
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Pattison Texas
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Something I've run across: Are we talking line OD or ID ?
I was going to use hard line which is 3/8" OD but only 5/16" ID with a Carter 4601-HP electric pump. This is for both the supply line and the return line (bypass-type regulator).
I know the rubber hose is 3/8" ID to fit over the brass fittings, but I don't want to use long lengths of rubber hose. I have two factory type 3/8 supply lines, one for supply & one for return , the 255lph EFI pumpI was running worked great @ 6psi return set up for a carb, but not enough volume for my EFI set up, so I replace the intank pump with a 470 gph pump & it works great from 30psi &up. but any lower pressure with the large pump does not work.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 3/8" fuel return line ?
[Re: hemienvy]
#2709636
10/23/19 07:50 PM
10/23/19 07:50 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Isn't the ideal solution to just plumb the regulator at tank on the return line, and just plumb the next size up short return then the supply iine?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: 3/8" fuel return line ?
[Re: jcc]
#2709638
10/23/19 07:57 PM
10/23/19 07:57 PM
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Joined: Aug 2011
Posts: 2,857 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,857
Pattison Texas
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Isn't the ideal solution to just plumb the regulator at tank on the return line, and just plumb the next size up short return then the supply iine? that is another way of doing it, I WONT do it that way, I do what works for me , underhood temps cause lots of fuel delivery problems, the fuel never gets a chance to boil with the return up front, although I do have to insulate all the plumming
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 3/8" fuel return line ?
[Re: CSK]
#2709644
10/23/19 08:29 PM
10/23/19 08:29 PM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Not sure how I can understand how fuel is "boiling", under pressure and flowing, in that at low demand, most of fuel flows back to tank, and at high demand , it flows into engine. How does it have time to boil?
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: 3/8" fuel return line ?
[Re: hemienvy]
#2709675
10/23/19 10:01 PM
10/23/19 10:01 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
top fuel
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top fuel
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
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Something I've run across: Are we talking line OD or ID ?
I was going to use hard line which is 3/8" OD but only 5/16" ID with a Carter 4601-HP electric pump. This is for both the supply line and the return line (bypass-type regulator).
I know the rubber hose is 3/8" ID to fit over the brass fittings, but I don't want to use long lengths of rubber hose. When discussing tubing, nominal size is the actual o.d. (exception being in the plumbing trade where copper tubing nominal size is not o.d.) Hose sizes typically are i.d. So a 3/8 hose will slip over a 3/8 tube.
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Re: 3/8" fuel return line ?
[Re: jcc]
#2709682
10/23/19 10:31 PM
10/23/19 10:31 PM
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Joined: Aug 2011
Posts: 2,857 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,857
Pattison Texas
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Not sure how I can understand how fuel is "boiling", under pressure and flowing, in that at low demand, most of fuel flows back to tank, and at high demand , it flows into engine. How does it have time to boil? LOL Thats my point, regulator in the rear like you said, fuel is not moving under low demand in the engine compartment. like I said, I will do & recommend what has worked for me, you can do it the way you want.
Last edited by csk; 10/23/19 10:31 PM.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: 3/8" fuel return line ?
[Re: CSK]
#2709707
10/24/19 06:49 AM
10/24/19 06:49 AM
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Joined: Dec 2003
Posts: 22,696 Bitopia
jcc
If you can't dazzle em with diamonds..
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If you can't dazzle em with diamonds..
Joined: Dec 2003
Posts: 22,696
Bitopia
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Not sure how I can understand how fuel is "boiling", under pressure and flowing, in that at low demand, most of fuel flows back to tank, and at high demand , it flows into engine. How does it have time to boil? LOL Thats my point, regulator in the rear like you said, fuel is not moving under low demand in the engine compartment. like I said, I will do & recommend what has worked for me, you can do it the way you want. We have a failure to communicate.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.
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Re: 3/8" fuel return line ?
[Re: jcc]
#2709725
10/24/19 09:00 AM
10/24/19 09:00 AM
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Joined: Aug 2011
Posts: 2,857 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,857
Pattison Texas
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Not sure how I can understand how fuel is "boiling", under pressure and flowing, in that at low demand, most of fuel flows back to tank, and at high demand , it flows into engine. How does it have time to boil? LOL Thats my point, regulator in the rear like you said, fuel is not moving under low demand in the engine compartment. like I said, I will do & recommend what has worked for me, you can do it the way you want. We have a failure to communicate. I think you are correct, it has been said by some manufacturers that the return regulator should be close to the carb or efi fuel rails for a more accurate pressure ?
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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