Another Power Valve Blown
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Another Power Valve Blown
I blew another power valve again. I go through about 1 a year it seems. I had a backfire on startup last time I took it out and it must have gone then. It is a newer Holley so it should have protection against this. I have no choke on the carb so it belches and gives me a little trouble on startup but after about 30 seconds of playing with it I have no problem. I new it was going to backfire I could just tell the way it started up. After a short ride tonight picking up my daughter it was not idling well. Finger over the vent tube and it floods out immediatly. Same as always. Off to the parts store. I guess I should buy them in bulk 
Instructor
Joined: Sep 2005
Posts: 141
Likes: 1
perhaps you should switch to a carb that does not use the power valve setup. i think edelbrocks do not use this feature; also, check the demon series carbs. i have used holley's for years, and can rebuild them in my sleep, but i have recently ventured into other brands, although i have not rebuilt them and can not tell you exactly what is inside them.
Thread Starter
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
My other choice has been a Demon carb but I'm not sold on one yet. I think they use power valves also. I'm not going to spend 500 for a carb just to prevent blown PVs. I can buy a lot of PVs for 500 bucks
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Pro
Joined: Aug 2001
Posts: 683
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From: mississauga ON
Originally Posted by nastee383
What are the syptoms of a blown power valve?
A blown power valve would probably flow extra fuel
even when it is not meant to.....creating a rich
condition. So look for the usual "rich" symptoms.
Fouled plugs, black smoke.
Team Owner
Joined: Jul 2001
Posts: 182,997
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From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
Originally Posted by nastee383
What are the syptoms of a blown power valve?
If the power valves are blown, I have to keep the gas pedal to the floor during cranking in order to start the engine and the engine won't idle for more than a few seconds before it floods again...
Last time, I only blew one of the power valves and the car would still idle, but not too good.. However, when I blew both valves at the same time, it was impossible to get the engine to idle for more than a few seconds..
Last edited by GrandSportC3; Sep 27, 2005 at 09:48 PM.
Instructor
Joined: Sep 2005
Posts: 141
Likes: 1
power valves are made of thin flexible materials; they screw in and can be easily replaced; however, an engine backfire puts alot of air pressure through the carb and will often make the thin flexible power valve tear (blow). it sucks.
Burning Brakes
Joined: Apr 2000
Posts: 1,076
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From: Dixie TN
power valve
Jegs and summit sell a small screw to put on the carb. It is supposed to keep the power valves from blowing. I haven't tried them yet, i just read about them. 
Last edited by A78Corvette; Sep 27, 2005 at 11:21 PM. Reason: spelling
Advanced
Joined: Jul 2005
Posts: 78
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From: Florida
it does work!!!!!!!!!!
Racer
Joined: Jun 2005
Posts: 409
Likes: 13
From: Lavonia Georgia
Originally Posted by Gordonm
My other choice has been a Demon carb but I'm not sold on one yet. I think they use power valves also. I'm not going to spend 500 for a carb just to prevent blown PVs. I can buy a lot of PVs for 500 bucks
