Holley 600 CFM Question

[Vette66AirCoupe]

Can a failed mechanical fuel pump cause gas to blow out the top of the rear bowl vent? Can a fuel pump actually fail and create MORE PSI's? I've checked the needle and seat and the float and all appears fine. Any ideas?? (427/390)

 

[vette-dude]

Sounds like a blown power vavle. Cheap fix. Be sure you get the correct size.
Randy

 

[jerrybramlett]

Can a failed mechanical fuel pump cause gas to blow out the top of the rear bowl vent? Can a fuel pump actually fail and create MORE PSI's? I've checked the needle and seat and the float and all appears fine. Any ideas?? (427/390)

No.

No.

You often can't see the grit holding a needle valve slightly open.

 

[studiog]

My 2 cents: Sticky float or needle & seat sticking open. Have you had any recent backfires through carb that might have blown the power valve?
Good luck

 

[Vette66AirCoupe]

My 2 cents: Sticky float or needle & seat sticking open. Have you had any recent backfires through carb that might have blown the power valve?
Good luck

I've never had a backfire. The unfortunate thing is that I will probably not get any feedback as to what was the root of this problem. My guess is they will simply rebuild it again. If I do get any answers I will certainly share them with the forum readers. Thanks to all for your comments.

 

[ctjackster]

repeated power valve failures in your Holley (perhaps you are not hearing the backfire over your sidepipes?) might suggest that you install a power valve protection kit - they come in a few different configurations, Here is one: http://www.powervalveshield.com/

 

[JohnZ]

Sounds like it needs a secondary needle & seat - the power valve wouldn't cause that - it's in the front (primary) metering block.

 

[rowingone]

Actually mine was doing that exact thing yesterday . . bought a rebuild kit which contained new needle and seats . . . fixed the problem up in no time - point is you cant tell from looking at the old ones . . I inspected mine and cleaned them thoughly but the new ones did the trick.

 

[JohnZ]

Don't use anything but genuine Holley parts, especially for needle & seats; the "generic" parts store rebuild kit needle & seats are usually junk.

 

[Ron Miller]

Don't use anything but genuine Holley parts, especially for needle & seats; the "generic" parts store rebuild kit needle & seats are usually junk.

The last genuine Holley part I bought only a couple of weeks ago was junk, a set of bowl & metering block gaskets from Autozone in a Holley blister pack. They were Holley brand but were foreign made and coated with a blue plastic like material. They apparently shrunk from the coating process, wouldn't fit the alignment pins and were obviously undersized. Took them back, we checked a couple of other sets on the carburetor to verify that the problem was not with the particular set I had. (It wasn't, they were all defective). Went to the NAPA store & bought a set of NAPA brand (which he said he had from several years ago, since he has little current demand for carburetor parts) & they fit perfectly. Also sealed perfectly & didn't block the accelerator pump passage like the Moroso set I removed.

I also had a set of the clear plastic Moroso fuel bowl level plugs which I removed, they had softened severely, apparently from the alcohol (translated "ethanol") used in some of today's gasoline. Put my old metal plugs back in, they work fine anyway.

My experience, for what it's worth. Junk is apparently available in all sizes, shapes, and brands these days.

rlm

rlm