return or deadhead

hi guys, carburetor guys
carburetor guys let’s talk fuel systems. What are most of you guys running return system or are you dead heading please share car and ETs. Motor etc.

Return now. It just works too nice not to.

68 Dart .. 527 hp small block runs 10.90s - Product Engineering pump and filter combo ....return is on the pump returns thru -8 hose back to the cell ..-10 line from pump to regulator in front of car .. have been as fast as 10.40 with this pump set up but with a different motor

Single 4bbl on a deadhead. Using a Magnafuel pump with a bypass at the pump. Running 8.9s on pumpgas.

Quick fuel 427 pump 100 micron filter dead head Pro Stock regulator runs fast enough sometimes

Similar, but with dual 4 bbl and mine is an Aeromotive 3000 pump with the bypass and filter at the pump. Also street car on pump gas.

4 cars in the stable, 3 have deadhead and 1 has a return. The 4th had a deadhead system for years but I switched it to a return style last year. Cars run 10.50-11.70s. The reason I switched the one to a return style is to try and see if it would work better with pump gas. 2 cars we run AV gas and 2 we run a mixture of pump gas/race gas. We've had issues with pump gas boiling in carb on a hot day. Since I switched the one car to a return style I ran straight pump gas last year and didn't have any issues with the pump gas boiling. I will eventually be switching the 2nd car over to a return style at some point so we no longer have to mix fuel.

Return. I can’t think of a reason to not use a return line, but Shilo says his is a dead head system and his stuff runs…well…FREAKING HARD.

MagnaFuel 500 2 x -10 pick up with -8 return at the pump. -12 to the reg (Aeromotive) and -8 to the 2 x 4 Dominators. Overkill for the fuel system but I was chasing a fueling issue (top end lean out) at the time and upsized all the fuel lines. The fueling system turned out not to be the issue but according to the data it helped

For several years I ran a simple deadhead system on my cuda using the little Aeromotive street rod 11203 pump and a -8 feed line. Ran 9.50s at 140+ mph at 3800 lbs. pump gas and all motor.

I upgraded to the Aeromotive A1000 pump using a -10 feed and -8 return. It ran no faster, but I didn't expect it to. I went w/ the return system to help vapor lock issues on the street...and it helped greatly.
Still using the same system feeding both the motor and the nitrous system well into the 8 sec range.

Using a stock tank w/ a welded on sump. Two -10 feed lines Y'd at the pre-pump filter inlet. The return is plumbed into the stock pickup tube.

how long would it take for it to vapor lock?

Mine is proably overkill. Feed is -12 to a Performance Engineering pump. Return to the tank is -8. From the pump a -10 feed line to a (hated by many) Barry Grant 4 port regulator. Four -6 to the carbs. Pump provides 30psi to the front. Regulated down to 5psi. 8.98@150mph, 3340lbs
Doug

When you shut the car off after it was hot and then try to restart it. If I got caught in stop and go traffic during the hot summer months it would start doing it also.

Aeromotive pump, with two Aeromotive filters and Aeromotive regulator that is deadheaded. I have a separate Aeromotive regulator designed for a return, but just haven’t felt the need to change it as of yet. 500 stroker with a single carburetor puts out 615hp on the dyno.

I have a 69 dart with a stock fuel tank, a blue pump, going to a regulator, and I noticed a hammering type sound at the regulator and my AFR gauge would go lean

to give you a more complete picture of the fuel system, which is being switched out today however, I just don’t want to do all this at the same thing occur

It’s a 3/8 sending unit going into the pump, going into a half inch aluminum line that goes to my regulator

The new system I’m putting in is a fuel cell with a -8 line going to the pump going to the 1/2 line. plastic tank

and of course, I’m trying to rethink it and thinking about a return line

however, I know I deadhead system as work for years for most people

I was also going to suspend this tank over my spare tire in the trunk. I have a question I was going to use 1 inch angle iron, if not larger on the ends and flat stock in the center to hold the straps what would you think would be the best aluminum or steel??? also will one or the other past tech?

I guess right now I’m not 100% sure if it’s vapor lock or cavitation

Sidenote, this happens when my fuel tank is full

Dead head stuff here on all of the cars. Weldon pumps with bypass to cell from pump set between 27-32 depending on car. All regulated down to 4.8-5lbs at carb. All 4 port Weldon regulators for single carbs. No issues ever with this setup. Been .99x-1.0 60's with this set up. Same stuff we run in the Vette. If its good enough for aerospace industry and Nasa it is good enough for a racecar.

How big is your vent?

Stock vent on the tank it is small the size of a vacuum hose


Great point though I’m a pipefitter so you think I would probably think about that
I know how important venr line is

Passing along info I have learned -

The return line must be at least as big as the supply line, minimum. Otherwise the return hose becomes the restriction. And if you are using a high GPH for application pump, it should be one size larger.

Tank to pump, one size larger minimum than supply line.

Tank vent minimum -8.

Much easier on the pump to maintain volume at <10psi than at >25psi.

We build a system to that spec, works perfectly. Fuel pressure rock steady on the Racepak. Fuel doesn't heat soak in the line. Put a diptube on the return in the tank, get a solid fuel flow with no aeration.

On a dead head system, fuel in the supply line just sitting there, for the most part, until the hit. What's that fuel weigh? It has to be accelerated in the line to meet the demands of the engine. Plus it has to be accelerated against the G forces of the car accelerating. With a return system, it's already moving.

I ran deadhead systems forever. They work. Won't anymore unless the guy insists. Heck, I have guys running low 9s at 3600# with Holley Blue pumps.

Tank in the front of the car makes things much easier.

I've heard this before, but many don't agree w/ this. One of the engineers at Aeromotive recommended the -10 feed and -8 return on my car and it works flawlessly.
Many factory EFI applications use a smaller return than feed also.

I don't disagree that someone would tell you that. The tech guy I talked to at a company that builds high end carb fuel systems we've used told me same or larger. Along with the rest of it. You'll get different stories from different places, even though they are the ones who design, test and make the stuff.

My thoughts were, if you run it up through 16' of -10 and return it through 16' of -8, how can the smaller line not be a restriction, to some degree, with a big pump? I want to control fuel pressure at the carb with the regulator, I want it to be consistent regardless fuel demand of the engine and we aren't running a lot of fuel pressure to the carb.

Not all return regulators and systems are designed the same way. Different parts and pieces from different manufactures will function differently.

We monitor fuel pressure at the pump outlet and the return side of the regulator. There's always more than one way to do something. I'm happy with what we have.

I agree. If what you have works, who is to argue that? The bigger return line makes sense to me too.

Mine is the same set up as yours.

So I'm curious as to why different people give different answers and I go look at Aeromotive's stuff since I'm not real familiar with it and I might learn something. Lord knows I'm wrong sometimes.

I see Aeromotive makes a variety of return style regulators designed for different GPH pumps. in the instructions for their 13204 carb bypass regulator, these lines...

"The enclosed Aeromotive regulator was designed to be used with fuel pumps up to 150 gph, similar to
Aeromotive P/N 11101. Performance may be degraded if a similar pump is not used-"

"Attach the fuel return line to the AN-08 bypass port located at the bottom of the regulator using a cutoff AN-08 style
fitting (Aeromotive P/N 15607 or equivalent) and o-ring. The by-pass line back to the fuel tank must be no smaller
than AN-08 size."


Then in the instructions for the 13224 reg, this, along with a chart...

"The enclosed Aeromotive regulator was designed to be used with fuel pumps up to 250 gph, similar to
Aeromotive P/N 11101 or 11104. Performance may be degraded if a similar pump is not used."





The big 13212 reg for 300+ GPH is made for all -10 stuff.



Keep in mind the -8 hose from any of these places is 1/2" ID at best. Some are smaller.


SO, the answer to "how large should the return line be?" is, depends. But it certainly can not be too large.

FWIW I can get one brand talked about here a lot for FREE . But I choose to run the Weldon stuff....

They are top shelf. No doubt.