Regulator for carb with EFI in-tank pump...

My Magnum 5.9 doesn't have fuel pump boss, and I'm tired of the noise from the Holley Red back by the tank. I'm about to go to one of the Spectra EFI tanks but I need to regulate it down for a carb.

Aeromotive makes 3 different regulators with this specific application in mind, but really, whats preventing me from using a plain old bypass regulator that I have lying around? Specifically my old Mallory 29387?

https://www.summitracing.com/parts/maa-2...T0aAuPDEALw_wcB

check out the comments.
you can, as long as it is plubmed right.
the guy in comments that didn't is doing the same basic setup you are and the smaller return line is messing him up.

This is the one I have
CLICK HERE

The one you have should work

I specifically used that regulator on my 95 5.9 Magnum long block with carb.
Used 3/8 for return line on my ramcharger and ended up having to run a 1/2 return because of the distance Back to the tank. Was getting some erratic psi numbers at times.
Other than that hiccup its been flawless.

I used a 91 OEM plastic tank with stock tbi pump. Drilled a hole on top of tank and used a bulkhead fitting for the return. So I could use the original supply fitting off of the sending unit.

I saw an install at a show with the Spectra tank that had the regulator on the body just ahead of the tank where the line runs. The return run was 18" or so. He was running a chokeless 4150 of some sort. He had split the output after the regulator to run 1 line to the carb and one to the Nitrous plate. Adjusted initially to 6psi and with fuel flowing into a catch can through orifices that matched his nitrous jetting and and needle/seat orifice flow, then jacked that pressure a bit to keep it fed up top (6.6psi at both the plate and carb inlets. The guy stated that adequate fuel supply and pressure was not one of his problems.

Anyhow, pros/cons of that setup? The packaging is tempting....

Car was a small block brand-X auto with ported factory heads of some sort, headers, 9.0:1, cam, converter, ET Streets, etc. 150 shot. A fairly conservative setup as these things go, and clearly a driver with strip time on it. Not super shiny and with some timeslips getting close to 10's.

You can mount the regulator back by the gas tank as long as the fuel line is kept cool. The fuel line will be dead headed so it will be more susceptible to heat. But it can be made to work, a lot of new cars are done that way.

Got it. Thanks Andy. Aren't new style return-less systems regulated by varying the pump output?

Also, on the fuel heat, is it less of a concern at carb fuel pressures? and do you think using Parker hose for most of the runs with hard line for the bends and debris prone areas isolate the fuel from conducted heat enough to prevent vapor lock with the extra heat from dead heading?

that's pretty much how our vehicles were from the factory. No regulator per se, but when the inlet needles were closed the fuel was dead heading.

I am in Southeast Tx, it gets hot here, I run 3/8 supply & 3/8 return, all line insulated to keep from heating up the fuel in the tank, regulator is near the carb it works very well, I drive my car & it has A/C.

What I had in mind was putting hthe regulator right next to the tank, and if there IS a vapor issue, either use the vapor return filter to bleed a little fuel back to the tank or use a second regulator at the carb set 1 psi below the back regulator and use the vapor return line as a return line for the minimal return fuel. This way it does not handle ALL the bypass fuel, just the 1 psi difference.

I would think a vapor return filter would be adequate...

Went from a barry grant external to an in-tank (tanks, inc.) FI pump setup and the same regulator works like a champ, no issues so far.