Holley Power Valve blocking and Edelbrock Fuel pump leaks

[TonyMadrid]

I need a little help from the gurus regarding Holley Carbs and Edelbrock Fuel Pumps.

First, with respect to a Holley 600 (not a DP), what are the pros and cons of blocking off the power valve and how is it done? I have read a thread where one guy had to do that to a Holley DP to get the carb to lean out and stop providing excess fuel.

Second, I have an Edelbrock Fuel Pump and I have it leak oil twice. I initially saw that due to the diameter of the pump, it was not completly seating against the timing case cover as it was butting against part of the casting of the timing case cover. I trimmed the timing case cover and the pump now seats correctly. However, it leaked oil again and I presumed it was the gasket so I installed a Felpro gasket and thought the problem was solved.
However I now see oil on the top of the pump but I cannot determine the source of the oil. The mounting flange is dry all the way around and there are no observable sources above the area of the top of the pump. I checked the oil pressure sending unit and extension pipe and fitting and they are all bone dry.

It seems like the oil is coming from the fuel pump, either a hairline crack in the pump housing or from one of the two gaskets that separate the three sections of the fuel pump.

As i am having a concurrent problem with low oil pressure, engine running too rich and loading up the cylinders, and fuel in the oil, I cannot run the engine to seek out the true source of the oil leak by the fuel pump. I will pull the pump and examine it.

Has anyone in here ever had any similar experiences with Edelbrock Fuel Pumps? Also, what is the possibility that the pump diaphragm has ruptured causing oil to pass past the diaphragm and work its way out through on of the pump housing gaskets? What about a rupture allowing fuel to enter the oil?

I am running an inline fuel pressure gauge and the gauge needle fluctuates between 6 and 7 psi but it is never steady. With a mechanical pump, should the fuel pressure gauge show a steady reading or since it's mechanical should it fluctuate as the pump activation lever/arm cycles up and down?

Any help will be greatly appreciated.

Tony

[Mr.Fixit]

Do not run a Holley without a power valve. If your motor is too rich, decrease the size of the main jets, but don't eliminate the power valve circuit. If you choose to do it anyway, Holley sells a brass plug that replaces the power valve, but don't.

[DAVID GAGNARD]

Tony;

I've seen a number of Edelbrock fuel pumps leak,not sure why,but have seen problems with them.... I have a Carter on my car,been there for almost 20,000 miles and have had NO problems with it,it's also a lot less expensive then an Edelbrock....

As far as the carb goes,I'm with Mr. Fixit on this one....Tried that a few years ago on a Holley 600 on a pickup truck,did not cure the problem,the only thing that cured my problem was replacing the carb....I would put a power valve with a very low opening (2.5 or so) and work on jets,if that does not work,try another carb.....

David

[Hotfingrs]

Sounds like you might a a couple of problems.....fuel in the oil, could be a ruptured diaphram in the fuel pump. You don't say what the plugs look like. If I'm not mistaken the 600 Holley has a metering plate on the secondaries, so you'll need the PV... use a 2.5 as suggested above...that's all I ever use. Check out the fuel pump, then start looking at plug color and play with jets.

[Jack21]

Tony,

Don't take out the power valve, it's there for a reason. But it must be sized correctly. There is a number stamped on the ring that tells you at what vacuum the valve opens. 2.5, 3.5, etc. First, measure your idle vacuum with a gauge. Then select the valve based on 1/2 your idle vacuum plus a half of a point. If your idle vacuum is 12", then your power valve would be 12/2 + .5, or 6.5.

As Mr. Fixit said, Holley does make a brass plug for tuners who want to remove the power valve. Have seen it used for two reasons. 1. Diagnosing throttle body to metering block vacuum leaks. 2. Changing the fuel enrichment curve on the secondary metering block if it has a power valve, to prevent leaning out at the end of a run.

I had a similar problem with a Holley fuel pump hitting the side of the oil pan rail and not sealing at the gasket and leaking oil.

Made a spacer plate or shim out of 1/8" aluminum the same size as the gasket. Then I put a pump gasket on both sides of the shim, and bolted the pump back in. Also, use a thread sealer on the bolts as they go through the casting into the oil. But the leak stopped.

If the pump diaphram is gone, you'll likely have to replace the pump. FYI, Edelbrock makes an adapter for the bottom of a Holley fuel pump that lets you run your fuel-in nipple into the bottom of the pump instead of the side. Solves fuel line clearance problems.