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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: AndyF]
#2738447
01/31/20 04:07 PM
01/31/20 04:07 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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Im 8 up 10 back to tank with reg after the carb. Mallory 140 with their regulator. Been running this setup on past 2 cars for 15 years. No other way I would do it Makes no sense to me why the return line would need to be bigger than the feed line; there's already going to be a reduction in volume from filling the carb, so having it the same size should be sufficient... IMO.  EDIT: Not sure of the manufacturer, but here's another schematic that's similar to what I posted above. That system should work just fine on most cars. I think that you could even put the regulator in the trunk next to the fuel cell and dead head the pressure line to the carbs and have it work okay. That is the way my Duster is setup and it works. Some people don't like the long dead head section but it is under pressure so it should be fine. Most OEM cars are that way, even the high performance ones. Thats true Andy, BUT they are ALL high pressure EFI, down here in the heat @ 6 to 8 psi for Carb use will have problems.
Last edited by csk; 01/31/20 04:08 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: Bypass type fuel systems (Carb)... Thoughts?
[Re: BradH]
#2738478
01/31/20 06:09 PM
01/31/20 06:09 PM
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Joined: Mar 2006
Posts: 9,835
MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,835
MI, usa
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Im 8 up 10 back to tank with reg after the carb. Mallory 140 with their regulator. Been running this setup on past 2 cars for 15 years. No other way I would do it Makes no sense to me why the return line would need to be bigger than the feed line; there's already going to be a reduction in volume from filling the carb, so having it the same size should be sufficient... IMO. EDIT: Not sure of the manufacturer, but here's another schematic that's similar to what I posted above. This is exactly what is on the current car. Flawless. Car makes north of 900. Previous car had a Mallory 140 and a Mallory return style regulator at the carbs. 8 in 8 out. It was constantly over pressure at idle no matter what adjustment was made. Same carbs with both systems. Finally added a second bypass like pictured in the trunk at the tank. We even bored the return larger in the regulator, Lines are bulky, more weight, more $ in fittings. Wasn't worth it. Doug 
Last edited by dvw; 01/31/20 06:13 PM. Reason: need picture
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: plycuda]
#2738506
01/31/20 08:31 PM
01/31/20 08:31 PM
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Joined: Oct 2003
Posts: 11,684
W. Kentucky
justinp61
I Live Here
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I Live Here
Joined: Oct 2003
Posts: 11,684
W. Kentucky
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the problem with the regulator at the pump it doesn't circulate the fuel up near the carburetor. The magnafuel pump has a return at the pump but that didn't help with the fuel getting to hot and boiling. I put a return regulator at the fuel log and its been good ever sense My fuel line runs up the inside of the frame tie, then it crosses and goes outside and into the passengers wheel well. It's away from the headers and I've never had any heat soak problems.
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: plycuda]
#2738507
01/31/20 08:31 PM
01/31/20 08:31 PM
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Joined: Dec 2016
Posts: 1,111
Usa
A39Coronet
super stock
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super stock
Joined: Dec 2016
Posts: 1,111
Usa
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the problem with the regulator at the pump it doesn't circulate the fuel up near the carburetor. The magnafuel pump has a return at the pump but that didn't help with the fuel getting to hot and boiling. I put a return regulator at the fuel log and its been good ever sense I can't imagine temp is a problem unless you're dealing with a really small tank. I never had any temp issues with my setup (I think it was 10 gallons), hot lapping, in August. Even still, how hot does the fuel need to get before it causes a timing issue?
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: sixpackgut]
#2738567
01/31/20 11:23 PM
01/31/20 11:23 PM
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Joined: Jan 2003
Posts: 11,711
Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,711
Portage,michigan
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Return line should be bigger than feed line so the the regulator does its job. An equal size return line can cause x amount of pressure by itself rendering the regulator useless
Placing the regulator after the carb insures fresh cool fuel at all times to the carb
Its not about the fuel system making the car faster. Its about the life of the pump. Not having a single fuel related issue when its 1 million degrees outside. There is always someone from Michigan that says its a worthless upgrade. But down in the south it's the best thing you can possibly spend an extra $100 on I fully didnt expect it to go faster, i figured the black pump gave it all the fuel,it needed in the first place. Just made the mistake of listening to others tell me my system was inadequate and should be upgraded It never failed, the pump still worked fine after years of use when i upgraded( foolishly) It gets hot up here too. 90 degree days arent a rarity. Hot is hot. Most racing and street driving was done in the summertime.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: dvw]
#2738633
02/01/20 10:12 AM
02/01/20 10:12 AM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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Why does the fuel get hot? Routing or pump stalling? Pump stall is alleviated by the rear bypass or running the pump on a PWM signal. Routing is easy enough to cure. You will see even most OEM's have eliminated tank return.
Doug Im sure you realize that efi does not have the same problems as the increased pressure raises the boiling point And Im not sure how many guys here have ever driven their cars for 8 hours straight across states. Yes, it gets somewhat warm in Michigan. I drove my barracuda there, i also drove to TX, LA, OK, MO,KS,TN,OH,AR,IN,IL,KY to name a few
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: sixpackgut]
#2738640
02/01/20 10:18 AM
02/01/20 10:18 AM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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I drove my '69 383 Super Bee with 4.10s from Virginia to Oregon and back... about 5 days of all-day driving each way. But that was in the late '70s, so it's probably not what you're talking about.  The Challenger has done multiple 4-hour drives at 65 to & from NJ, which probably is. Oh, but you mean in THIS decade.  /
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: B1MAXX]
#2738666
02/01/20 11:41 AM
02/01/20 11:41 AM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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Eddie Miller went 8.50s in 06 and 7.9x in 08 with 2 holley blue pumps. And one was dangling only held in place by the fuel line
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: BradH]
#2738669
02/01/20 11:44 AM
02/01/20 11:44 AM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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I drove my '69 383 Super Bee with 4.10s from Virginia to Oregon and back... about 5 days of all-day driving each way. But that was in the late '70s, so it's probably not what you're talking about. The Challenger has done multiple 4-hour drives at 65 to & from NJ, which probably is. Oh, but you mean in THIS decade. / I didn't realize you were so much older than me. Jeez, i invited you to be my copilot. Not sure you would have been any good to me 
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Bypass type fuel systems (Carb)... Thoughts?
[Re: BradH]
#2738684
02/01/20 12:04 PM
02/01/20 12:04 PM
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Joined: Jan 2004
Posts: 8,251
fredericksburg,va
cudaman1969
master
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master
Joined: Jan 2004
Posts: 8,251
fredericksburg,va
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Forgot one thing had to do over, this was my system. The needle and seat are the biggest restrictions # 6-8 everywhere else. Ran 5.50 @125 with a holly blue pump and cell in the front. 499 Indy, dominator, pg. @125 mph, I don’t think it was running lean
Last edited by cudaman1969; 02/01/20 12:13 PM.
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