I know it only takes a couple minutes to remove the primary bowl, but is there any way to check a holley power valve without taking the crab apart?
Gary

IF ITS INDEXED YOU CAN USE A HAND VAC. PUMP TO CHECK IT THATS THE ONLY WAY I KNOW ,,SORRY

You will get very little idle/air mixture tuning capabilities (i.e. you see little variation in engine idle quality or rpm when turning your mixture screws in or out to the point where you couldn't kill the engine by turning the screws). Another indication is rich idle condition, or heavy resedue line on transom. I don't know of a way to check the power valve with the metering plates on. If you do take it apart be sure to use the Holley rubberized gasket material to reinstall to make future power valve changes easier.

AZDominator
It's probably blown then. Symptoms, rich/rough at idle, smooths out when there's a vacuum leak in the manifold.
Thanks,
Gary

AZDominator,
BTW, no transom, it's on my '68 Vette.
Gary

Was your power valve blown Gary? One of my engines doesn't respond much to idle mixture screw adjustment and am trying to figure out if I have a problem. Have not run it yet on the water.

Dave

Dave, if your carb does not respond to idle mixture adjustments, I know how to remedy that.

Why are you answering a thread from 2002? Just curious.

Dave, yes it was. Wow, that was a long time ago.
BTW, changed to a mechanical secondary carter that I had around. It turned the car into a rocket!

Just diggin up bones F31 Flirting with the 800cfm holleys for this season and trying to figure out the triggers and how to recognize things. I'm good with a qjet, but my experience is 20yrs stale on the holleys. Any tips you have would be nice. I think my primary throttle plate may be open a little to far on this carb but could also be the PV. The other engine responds well to idle screws but ironically is the engine that I've had backfire a couple times during tuning.

Thanks Gary. Rocket ship ehh? That would be trouble for me on the street

Dave

The quickest way is to plug the primary vent. If the engine does not stall then be suspicious of the power valve. This is not a scientific way mind you, just an indicator. If you run Holley’s then you should get a power valve tester. I say this because brand new power valves can be off the index as much as 4 to 6 points

Roby