Fuel Pressure Regulator Connection & Mounting Edelbrock AVS2

I've been running a Holley style Quick Fuel 735cfm dual side fuel inlet carb feeds with a Carter mechanical fuel pump and no fuel pressure regulator. I also currently have a 1/4" fuel return line that connects at a 3 nipple fuel filter. Here in CA with the 10% ethanol fuel, the return line helps greatly to prevent vapor lock.

As an experiment for improved throttle response I've recently purchased an Edelbrock AVS2 800cfm carb. I see that the fuel inlets on the Edelbrock are both on the rear of the carb facing the firewall instead of on the side of the carb like the QF. The AVS2 is sensitive to fuel pressure and wants to see 5.5 to 6psi max, so I want to install a bypass/return style fuel pressure regulator (Aeromotive 13301). I'm only into the mock up phase right now and have not even removed the QF carb, but with my higher than stock Edelbrock Performer RPM intake, it's looking like I don't have much real estate to mount the Regulator at the rear of the carb. I prefer to plumb the regulator after the carb instead of before, per Edelbrock advice, to minimize fuel pressure fluctuation and keep things more steady. I will have a 3/8" return line from the regulator back to the fuel tank to keep the fuel free flowing and cool and will replace my 3 nipple fuel filter with a standard 2 nipple filter since the regulator will now connect to the return line.

Does anyone have a recommendation on a clean looking fuel pressure regulator installation location in line with what I'm trying to do? Photos are appreciated

One idea is to use Edelbrock's fuel log shown here, but I'm not that familiar with their banjo fittings. Can I connect the regulator on the end of the driver side portion of that fuel log? If I do, then I need to do a 180 with the return line to connect back to the current return line that runs down the passenger side - OR I can run the new 3/8" return line down the driver side, diving under the steering column I guess?

Here’s the current setup.

I wish i could find a fuel rail that will fit the AVS2 with a tee- port in the middle between the banjo fittings to connect the regulator to, so as not to disrupt the carb fuel supply. Or if I just connect the regulator off the passenger side banjo fitting does it accomplish pressure regulation without being before the carb sees fuel (at least at the same time the carb sees fuel)? Example AVS2 with banjo fitting below.

I might be overthinking this. What if I just install a nipple at the passenger side banjo fitting end and connect the fuel regulator to that? Then it’s not before the carb sees fuel and still reading overall carb pressure.

This may not be the cleanest or the best setup , I’ll probably be changing it eventually, but it works . Hardline from the tank , to its factory end spot, rubber line to the pressure regulator in the inner fender, which I don’t know if you are using a high pressure electric fuel pump or not but the edelbrock 174053 isn’t bad, I’ve had it in use for 5+ years , and then rubber line to an aluminum line up the block like factory, to another rubber line , to an edelbrock 8126. Again probably too many connections and rubber lines , but it hasn’t let me down. Here’s the best pictures I could take

thanks, but I'm trying to keep the regulator AFTER the carb, not before it. I'm running a carter mechanical pump that supposedly puts out around 8-10 psi (never measured), not an electric one.

If your fuel system worked ok with the H carb, it will work with the AVS. The Carter/Edel float system has more leverage on the n/seat, so it provides more constant fuel level & will withstand more pressure, contrary to popular belief. I have run 10 psi at the track, no problem.

First thing I would do is measure fuel pressure

If your fuel pressure is 7 psi or lower with your mechanical Carter fuel pump , seems like a lot of unnecessary hardware and work

I run a mechanical fuel pump on my 432 Stroker

800 AVS2

7 PSI

Factory 5/16 fuel line
No return line

Factory AVS fuel line to carb
Carter .110 Needle and seats changed over from Edelbrock

3/8 Float Settings

91 or 93 Octane with 10% Ethanol

Never experienced vapor lock ever on hot summer days in six summers

Supports a 500 HP 383 / 432 on the street

Great Street Carb , to a point

More interested on how the Edelbrock 800 AVS2 compares with the Holley Quick fuel , especially up top in the higher RPM range full throttle

I already know in the lower off idle and cruise


Let us know the results when you get everything figured out

Thanx

Thanks all. Just a reminder, I live in California with 10% ethanol in the fuel. A return line is necessary, which may not be the case for where you live. I have one now and I ran without one previously and the fuel system prefers the return line.

I will take the advice of measuring fuel pressure with my current setup prior to swapping carbs. The new carb is the AVS2, not the original AVS. Supposed to be an improvement. Not sure if it's more sensitive to fuel pressure.

Sorry, I do not understand something. Why would you install a fuel pressure regulator after the carb? I don't understand how that would control the inlet side to the carb.

Bird 426 said:

Sorry, I do not understand something. Why would you install a fuel pressure regulator after the carb? I don't understand how that would control the inlet side to the carb.

Click to expand...

The way I'm understanding it is that the regulator can control pressure when installed before or after the carb, but after the carb requires a return line. I was thinking of it previously as a just a valve and that it needed to be before the carb, however, the regulator can be adjusted to control the pressure of the fuel system if a return line is used, which also requires a return style regulator. If you look and compare regulators on the Summit Racing website, some regulators are return style and some are not. Here's a simplified explanation from Holley where they describe a before carb deadhead regulator and also the after carb bypass style:

A deadhead regulator controls fuel pressure by restricting fuel flow between the pump and the regulator. This not only places additional load on the fuel system, but the amount of strain increases as pump volume and flow increases. In contrast, a bypass regulator controls pressure by returning excess fuel out of the bottom port and back to the tank using a return line.


https://www.holley.com/blog/post/selecting_the_correct_regulator_for_your_car/

Ive had my setup for over 5 years with very heavy use, I also accidentally ran 5/16 line which causes more strain. I didn’t know the return had to be equal or greater than the feed , so I thought I could get away 3/8 feed, 5/16 return, had to flip them. Everyone likes to overthink everything, there’s nothing wrong with running it before the carb with a return line to tank. I can start the car easy when it’s 10 degrees or 100 degrees, I can run the car at 80 mph for 3 hours in 110 degree heat, I can’t drive the car when it’s below freezing. I’ve done probably everything “wrong,” I’ve driven the car probably in every normal extreme weather without reading a million articles, and it works just fine.

Bee1971.
Your fuel pressure with the 0.110" n/s should probably be about 0.5", not 3/8" to maintain the correct fuel level.

That chart you posted is based on the Carter Competition Series Float

Are the Edelbrock Floats the same size ?

Because the Edelbrock carbs come with a .0935 needle and seat and 7/16 float settings

Carter Competition series at .101 needle and seat and 5/16 float settings