I'm wanting to run an aftermarket universal fuel pressure regulator. In order to make routing hoses easier i was wondering If I could take the regulator off the carb (where the feed and return attach to the carb, and just run a line with a T straight from my regulator to each fuel bowl. Then I would have the regulator return go to the tank as normal.

 

If thats a nikki carb it has a feed and return line. The feed goes to both bowls. The return is slightly restricted and returns via the smaller hard line to the tank. You can dead head the feed line at the carb by plugging the return but then you have to make sure the psi is correct and less than 3 psi.

 

OK, what's your advice to plug the line, I would end up running a return from my regulator to the tank, so in my mind without looking at any diagrams it functions the same but adjustable and future proof.

 

Could I actually just right to the carb no aftermarket regulator. What's the biggest fuel pump i can run on a that. With return line

 

No matter how you plumb the carb, max pressure at the needles is 2.5 to 3 psi. Any higher and the carb will flood.

When I ran a Nikki on my race car, I had good luck with a Holley 12-804 regulator using a Carter 6psi electric pump (P4603HD is the current part number). I plumbed the carb both dead head (no OE return line) and with the OE return working. The 12-804 Holley regulator is not designed to use a return line. So you have to use the OE bypass on the carb. You should add a low pressure fuel gauge (0-15psi) between the carb and regulator. Get one that is liquid filled from a reputable company.

For plumbing, the supply line was a -6 (3/8") line from the tank to the carb. Later when using a bypass, I plumbed it with a -4 (1/4") line to the tank.

The return line made it a little easier to check float levels and set fuel pressure with the engine off and the pump running because the return line creates a "leak" that simulates a running engine.

 

Thats the setup on my SA with the hogged out nikki.

 

I bought a similar setup. Kinda sucks because I bought greddy braided line, but with all the AN to NPT dapters ($$$$) that would be needed im not using it untill I run fuel injection.

 

I would advise against this "if it ain't broke, don't fix it" when it comes to the Stock Nikki Carb. I added an Edelbrock inline glass "see through" fuel filter as an extra form of filtering and being able to see if there was debris or contamination. It was not necessary per everyone's advise and also created a potential fire hazard. Adding it meant that if for some reason the glass fuel filter broke or the seals leaked; it would be spraying fuel all over the hot engine bay. The other issue was that my startup and gas delivery had a small hesitation compared to before. It's one more obstacle you are adding to the fuel delivery so while the fuel delivery difference is minimal; it is apparent.

 

Can you give more details on why you want to add a fuel pressure regulator?

The stock fuel pump and feed/return lines are more than adequate for a stock (or slightly modified) engine and the system is very reliable.

As others have said, fuel pressure is very sensitive. A new pump and or regulator can make things tricky. Aftermarket pumps need a return style regulator and that can cause issues with the stock diameter of the return line.

Here is a thread I started for reference, when I installed a large streetported 12A and aftermarket pump and regulator. https://www.rx7club.com/1st-generati...ation-1116260/

 

I'm running a large street half bridge with stock nikki. I havent modded the carb yet but I will soon after the first few drives. I have enough hose of 1/4, 5/15, and -6 to run new fuel lines which i will also do when I convert to fuel injection. I'm really not wanting to modify the gas tank till I do injection though
I also have an aftermarket 7 psi fuel pump.

 

You should have mentioned this in the beginning and it would have made better sense to everyone -lol. Yes, in that case - adding the supporting mods for a SP+ engine and a hogged up Nikki is a necessity. If you are doing a SP / Half Bridge Ported engine - investing in a Prepped Weber or Holly from Racing Beat might be the better option. If you are planning fuel injection, i have heard great things about the Holly Sniper EFI system.