Holley guru needed , leaking diaphram

[grego37]

I have a holley 830? or 850? DP (i forget), its basically new.
I've noticed that my intake had some fuel stains under the primary bowl, so I reached up with my finger and the accelerator pump was wet, same with the secondaries but not as bad.
I went to the local parts store and purchased 2 new diaphrams, and installed them, Im having the same exact problem, just on the primary.

Why is that rivet in the center of the diaphram?, I believe it is leaking from there.
can I put epoxy or something around the rivet to prevent this?

thanks.

 

[D.Hearne]

That's not a rivet. Thats the part the pump arm pushes on. With the pump housing screws tight, it shouldn't leak.You got the diaphram on correctly, not upside down? You might also have a problem with the bowl gasket.

 

[D.Hearne]

What size motor you got that 850 on anyway?

 

[thehueypilot]

Ahhhh....that great Holley quality (lack of) strikes again. It could be a warped pump cover or your bowl screws need tightened down more or you over tightened the bowl screws and cut the bowl gasket. It could be leaking from the bowl and running to the pump cover and dripping from that spot.

 

[D.Hearne]

I don't think it's bad diaphrams. Not likely the one's that came with his carb AND another from a parts house (that came from another batch) would both be defective. I'd bet it's from the bowl to metering block, or metering block to throttle body gaskets that the leak is coming from. Like the infamous warped metering block? Never seen one, but heard of a few of those.

 

[grego37]

its on a 408w and I think its actually a 830 DP,

Its not the metering or bowl gasket for sure.
and I put it in correctly, didnt over tighten, torqued evenly.
any ideas?

 

[D.Hearne]

Take the metering block off and check to see if it's flat. Also inspect the pump housing. You've got an 850 DP, they don't make an 830. List # should be 4781 on the choke horn.

 

[D.Hearne]

One other thing to check, when you open the throttle, does fuel squirt out of the two pump nozzles in the throttle bores ? There's a remote possiblilty that the passage is blocked and when you open the throttle, the diaphram would rupture when it's compressed against pressure build up from a blocked passage.

 

[grego37]

That's not a rivet. Thats the part the pump arm pushes on.


I was told it was a rivet or equivelent fastener. thats what fastens the metal center to the rubber on the diaphram. and what people do on show cars (who are super anal about a drop of gas on their intake), they put some epoxy or JB weld around this rivet to ensure that it seals.

anyone done this?

all gaskets are good, definatley not leaking from any other area except dripping off the arm of the accel. pump.

 

[grego37]

yes I am getting squirt out of the 2

 

[grego37]

I called Holley, they said its most likely the plate is not flat or its warped, it happens.
they reccomended sanding it flat on glass with some wet 300 grit.
I'll give it a shot

 

[D.Hearne]

I've never had a new accellerator pump diaphram leak. On those show cars, they sit up alot and rarely ever get started, so yea, I can see them leaking from dried out diaphrams, but not from a leaking rivet.