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I`ve seen those regulators on 6-second pro stock cars so I doubt very little if at all.

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I ran low 9's at 147 mph with no problem with one. they are good regulators,sometimes i wonder why i switched to a magnafuel and product engineering.
no change in performance just change in my pocket now.

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At what point is the Holley regulator that comes with their fuel pump a restriction to the flow to carburetor needle and seats? I have a Mallory Comp 250 fuel pump feeding into one of the Holley regulators.......is there a problem?

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Granted this was on a dyno (static, no acceleration to overcome)But one day last year I was testing a 572 Indy engine. It should make around 900 HP. after a warm up and short pull I made a full pull to 7000. Timing was backed off and it made 875 but the BSFC got weird around 6700. I have a two fuel pumps on my dyno fuel cell. They each feed into a fuel log that feeds the engine being tested. A simple 90 degee valve and flip a switch and I can change from a Holley blue to magne fuel 500 fuel pump. OOOPS,I didn't change pumps and I was testing with a HOLLEY BLUE PUMP and reg. 875 HP thru a blue pump and std BS regulator. Bob George is right, I always want to over bulid the fuel system but is pretty amazing what some of the basic stuff can do!

Mike @MM

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Basic system are adaquate to a point,but with todays demands,big inch engines,big manifolds,big carbs,big jetting,high HP and RPMs can drive tuning fuel systems to new levels.As we constantly upgrade engine combos we have found our fuel systems that functioned flawlessly over the years were our worst tuning issues.As Mike said always over build your fuel system,it's one big problem that can be eliminated.Be very careful of restrictive fuel filers,match filter flow to pump flow and pump flow to engine demand.

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Your pump is probably more of a restriction then the regulator. Hopefully Monte Smith will chime in here, as they have seen data from the data logger, and the regular Holley Regulator was the best you could use. Also to let the reulator "float" and not mount it solid.

Jeff

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Your pump is probably more of a restriction then the regulator. Hopefully Monte Smith will chime in here, as they have seen data from the data logger, and the regular Holley Regulator was the best you could use. Also to let the reulator "float" and not mount it solid.

Jeff

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...utoh...i was wondering about that...i have my reg. mounted soild and believe i have a fuel delivery problem thats beginning to crop-up..i don't have a cowl mounted pressure gauge, but i'm installing 1 this weekend,so i can monitor the press. durning the pass...i'm also running the blue pump with the holley reg...with no issues until this past weekend @ Norwalk.

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Be careful as far as fuel pressure against fuel volume, fuel pumps have been known to aireate (SP?)the fuel with air which will read as pressure and you still can not have enough fuel volume to make the car run properly. I use the "jet it up enough to slow the car down" method as the way to test my fuel system If you can't fatten the mixture up enough to make the car slow down in the 1/4 MPH you don't have enough fuel delivery and volume. I have seen fuel restrictions in the fuel system that was not caused by the fuel pump or regulator I use the largest Viton tip needles and seats I can find, I also try and make sure to keep all of my fitting in the fuel system as large as possible and I don't use 90 degree elbow fitting, I use 90 degreee sweep fittings if I have to use a 90 degree fitting. Lots of ways to get mess up on race cars

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I have read where they tested a Holley Blue pump with the matching regulator and the pump would free flow 110 GPH into a bucket without the regulator and then with the regulator installed and set at something like 6PSI it would only flow 70 GPH free flowed into a bucket. So, yes the regulator does use up some of your flow potential.

That is why I started using a return line with a Back pressure regulator installed AFTER the carb, years ago.

The supply line is -8 and loops around on the right and the return is -10 on the left.

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Which Holley regulator are you talking about? If it's the one which comes w/ the blue pump, I switched to a Mallory regulator after a local shop showed me how much more restrictive the standard Holley regulator's passages were than the Mallory's. However, I know Holley offers some better regulators that should be comparable.

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