So I'm swapping a 350 into my V6 1989 firebird, in which I just installed a brand new in-tank fuel pump. From reading the V6 to V8 swap thread I know I need a 3 to 1 fuel pressure regulator with a return line. Does anyone have some part numbers they could throw at me? (I dont want to buy some junk and waste my money) As well as any installation tips because I'm pretty new to this. Also, what psi should I shoot for? I plan on running a 600cfm carb. thanks

 

Aeromotive makes a two stage regulator. Stage one is a bypass regulator that can drop 60 psi to about 12 psi. The second stage drops the 12 to 5-7 psi for the carb. I installed on a Walbro 255 LPH pump that ran at 50 psi and it worked great to feed a holley at 6.5 psi.

Not cheap, but works well.
Part number is 13220

Don

 

I went with a Holley #12-881 fuel pressure regulator on my setup. It has a 3/8" NPT inlet, outlet and return line, a 1/8" NPT gauge port and is adjustable from 4.5 to 9 PSI. I am running the stock fuel pump in my 1991 RS and it is feeding a Bigs Performance Next Gen 780 carb, sitting on top of a 480HP 383 Stroker. Easy install and has worked perfectly for me.

 

I've only found one bypass style regulator made expressly for carburetors. But that doesn't mean there aren't others.

https://www.holley.com/products/fuel...parts/12-803BP

Presently I'm using a Holley Blue pump in the same location as the original fuel filter for an EFI engine (86 IROC).
3/8" supply and a 3/8" return although the return necks down to 5/16ths at the tank. I experimented with a smaller return line but found the fuel pressure to be unpredictable between idle, cruise and WOT. I use an externally mounted fuel pressure gauge that I can view from drivers seat (it's stashed under the cowl hood). With the 3/8" return, the pressure varies very little.
Pressure is set to 5-1/2 PSI.
MIne is mounted on the passenger side frame rail near the rad but that was more because that's where the existing lines were when I was using a mechanical pump. On the Trans Am (carbed BBC) the regulator is mounted on a small tab and fixed to the camber plate on the drivers side. Seeing as this is where the EFI fuel lines land before crossing to the engine, it's a handy location if the lines are still in place.

 

Holley alone has about a dozen for Carburetors that are a Return/ Bypass style.

The Holley 12-803BP would actually be one of the best options for you, as a Holley Part that is not stupid expensive.

It is a higher flowing model compared to most of the other Holley Carburetor Regulator Models.
It is made for use with Electric Fuel Pumps ONLY.
It also requires the same size Return-Line as the Supply-Line.

 

Aren't the return and supply lines different sizes though?

 

Yes. Supply is 3/8"
Return is 5/16". On some models (as in the several I've owned) there's also a 1/4" line for the vapour canister.
What I found was that the OEM return wasn't large enough to keep stable fuel pressure under varying conditions. Whether you would experience the same can only be determined by experimentation. You may be OK.
The issue was primarily with the difference between a stable idle pressure and what was seen at WOT such as might be experienced at the top end of the dragstrip.
Now having said that, if I had a higher capacity pump than the old Holley Blue, my results may have been different.
As it is, I added a -6AN line for the return and spliced that into the original 5/16" stub at the tank.
Whatever the cause and effect might be, the larger return made a difference.
So far so good but this season will see a new pump and reconfigured lines.

 

Many Regulators will use a smaller Return Line size.

The Holley 12-803BP requires both lines be the same (Stated in the Instructions).