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Weeping from under Holley discharge nozzle

General engine tech -- Drag Racing to Circle Track

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shoedoos
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Weeping from under Holley discharge nozzle

Post by shoedoos » Sun Oct 06, 2019 5:52 am

Rebuilt Holley 390 double pumper, completely stripped and back together with new consummables. Floats set so they dribble out sight plugs when rocked, accelerator pumps set to squirt immediately, white pump cam.

Fire up and the thing idles nicely, give it a squirt, no stumble and a good stream from the primary discharge nozzle (#35). The nozzle starts out nice and dry underneath, then its like a well overflows and it weeps (very wet) from underneath the nozzle. After a couple of seconds the wetness drys and engine returns to a dry idle. This wetness soaks the top of each primary throttle bore in the immediate vicinity of the discharge nozzle.

I initially thought the thing was not tight, so nipped it up a bit more, tested again same thing, got to the point I wasn't going to tighten anymore for fear of stripping thread. Take off the nozzle and replace the two gaskets (top/bottom) - fire up and same symptoms.

Tried a different discharge nozzle (#31) from another carb, new gaskets, same issue.....the weeping happens if I just touch the throttle, whack it or if I roll it through into the secondaries. The secondary squirter stays dry throughout..anybody have ideas?

steve cowan
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Re: Weeping from under Holley discharge nozzle

Post by steve cowan » Sun Oct 06, 2019 6:08 am

Did you replace accelerator pump diaphragm and umbrella??
As far as stripping squirter thread, I did that on my demon carb, ripped thread clean out on secondary side,
Still not fixed :twisted:
steve c

shoedoos
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Re: Weeping from under Holley discharge nozzle

Post by shoedoos » Sun Oct 06, 2019 6:53 am

yes to the umbrella, not 100% on the diaphragm, will check it....I do remember them being very crusty and hard, so I'm pretty sure I changed them out.....are you thinking the diaphragm might be releasing late and surging?

steve cowan
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Re: Weeping from under Holley discharge nozzle

Post by steve cowan » Sun Oct 06, 2019 7:03 am

I had a meeting at the track earlier this year and a couple of times my car was hard to start, never happened before, anyway when I got home I found squirter leaking when car turned off and even when the carb was on the bench, I checked for damage to arm etc and adjustment, I run mine with no preload on arm to accelerator pump.
So I replaced the diaphragm and umbrella and problem gone, I could not find anything obvious at all and I had never seen it before either.
steve c

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