Regulator question

[67 455 Bird ragtop]

While I'm still kicking around with using either an in-tank or out of tank fuel pump I have a rather silly question about the regulator ports. Does it matter if the ports are 3/8 npt and you put fittings on them to have -8 feed and -10 return ?? In other words does it really matter what size the ports on the regulator are ?? I'm guessing not since most fuel pumps have a 3/8 outlet and people put -8 and -10 lines on them.

[Schwartz Performance]

It does matter, but only based on your pump volume/psi, engine volume and psi requirements, (horsepower and carb or EFI) . The better you match the pump to the engine, the less it matters.
If you have a pump supporting 1400hp on a 350hp engine, there's a lot of returned fuel, which would require a larger port on the reg otherwise there's a restriction, putting strain (backpressure perhaps) on the pump.

-Dale

[67 455 Bird ragtop]

Guess that makes sense. Close to 600hp 850 cfm quadrajet carb motor, 255 lph Walbro pump on a Mallory 4309 regulator ( what I currently have). The regulator has 3/8" npt ports. But I plan on running -8 feed line and a -10 return line. Should be sufficient or are the line sizes over kill ??

[Twentyover]

Return line probably overkill, also can the 3/8 NPT fitting be drilled for larger ID?

[Schwartz Performance]

You can probably get away with -8 return but being a 10 won't hurt.

-Dale

[F-Body International]

Guess that makes sense. Close to 600hp 850 cfm quadrajet carb motor, 255 lph Walbro pump on a Mallory 4309 regulator ( what I currently have). The regulator has 3/8" npt ports. But I plan on running -8 feed line and a -10 return line. Should be sufficient or are the line sizes over kill ??

Awesome setup...600hp with a quadrajet carb. Out of curiosity, who did the carb and what intake are you running? Once making good power with those carburetors, I've heard getting fuel to flow through them is the main hurdle. You have it set up with electric pump, large lines and return so that's good.

[67 455 Bird ragtop]

Awesome setup...600hp with a quadrajet carb. Out of curiosity, who did the carb and what intake are you running? Once making good power with those carburetors, I've heard getting fuel to flow through them is the main hurdle. You have it set up with electric pump, large lines and return so that's good.

The 600hp is a computer estimate based on engine size, cam setting, and such. It said from 550 to 600 hp. I figure closer to 575ish. The carb is a refurbished Edelbrock 1910/9975 850 cfm q-jet. Cliff Ruggles is doing the carb. It's at his place now. He's really the only one to send a q-jet to. He likes the Edelbrock castings. They usually only need an accelerator pump up grade and some fine tuning of the rods and jets. HOpe to have it back in 3-4 months.

[F-Body International]

The 600hp is a computer estimate based on engine size, cam setting, and such. It said from 550 to 600 hp. I figure closer to 575ish. The carb is a refurbished Edelbrock 1910/9975 850 cfm q-jet. Cliff Ruggles is doing the carb. It's at his place now. He's really the only one to send a q-jet to. He likes the Edelbrock castings. They usually only need an accelerator pump up grade and some fine tuning of the rods and jets. HOpe to have it back in 3-4 months.


That's cool, Mr. Ruggles is definitely the go to guy for Pontiac and any quadrajet advice. There is also Sean Murphy Inductions (SMI) for quadrajets. SMI even offers porting service that brings these qjets to over 900cfm...crazy for a GM carb! I was going to run quadrajet on mine but switched to a different route. Cliff quoted me 1 year turn around time on my carburetor when I called in. He must have a huge customer line on carbs and other engine projects...maybe he's writing another book haha. I think Cliff has a couple customers clocking 9's in the 1/4 mile with those old quadrajets.