Holley Carb help

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bill paynter

67 Cuda
Joined
Jun 23, 2005
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So, Ca.
I put a new 600 Vac. sec. Holley on my car this weekend ran fine at first.

My problem came when it backfired a few times while rev. it up and then the car would'nt idle below 1500rpm, I turned to idle screw all the way out still no change

my question is if I blew out the power valve would it cause the car to idle at a high RPM any thoughts
 
Sounds like it blew out a portion of the base/mounting gasket and created a vacuum leak. Most holley's have blowout protection on them, unless it's a older carb.
 
replace power valve and check gasket and clean out your base plate and cheack timing just incase :thumbup: or go with a afb'carter or elderblock.
they have been trouble free for me in the past,just keepin it neet on the street. Just me. :)
 
Sounds like you blew the power valve,but i thought all Holleys came with power valve protectors now?anyway check to see if you blew it,change if you did check/replace base gasket,deffinately check timing and adjustments to carb,use a vacuum gauge when making adjustments...Holley 600's are a pretty basic carb design should'd be hard to figure out.....oh and a heads-up depending on how back it back-fired you might have blown the mufflers too...
 
One other thing to check is that when it back fired that it may have bent the throttle blades a touch and this will make it rpm higher, depending on what rpm's the engine was turning at the time of backfire. We have had them backfire and blow out the small teflon seals out of the throttle shafts and create a vacuum leak, makes it hard to find but with some carb spray will definitely show where.
 
I automatically think Power valve when this happened, I'll Check the gasket first
thanks for all your thoughts
 
Generally if a power valve is blown out it will create a rich condition and not a lean condition as it will leak fuel into the engine IMO.
 
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