What are the symptoms of blown power valve

[sand1man]

Can some tell me some of the syptoms of a blown power valve, I have a holly 650dp, thankyou

 

[chemeng]

Mine would run choppy at first, then die completely after it warmed up. Dumping way too much gas into the intake, could smell gasoline like it was really flooded. Had a major vacuum leak and it backfired through the intake.

 

[12sec67]

also durring acceleration it tends to surge

 

[sand1man]

thanks for the info, sorry it took so long to get back, mine has a hard time running at first then once it warms up it idles ok then also at wot it sputters if I let off a half inch or so it runs smooth just low on power, I was wondering about a power valve because it started out of the blue

 

[MitchGT]

It seems like you are most likely to have a blown power valve if you had a misfire up your intake manifold. I had inserted my distributer off a little, had a misfire through the manifold, then the car started to run really badly(worse than just the timing problem). After just a few miles of running REALLY richly, I had so much carbon in the cylinders that it would detonate badly even after setting the timing to old 6 degree specs. If you had a blown it you would know. If however your car had low vacuum for a different reason, it would allow the power valve to open a bit, which would make the pre-existing problem worse. it would run so rich you couldn't fix it with just the idle mixture screws.

 

[Max Power]

One way to tell if your power valve is blown is to put your finger over the little tube that is part of the air horn. If the car dies when you do this, the valve is blown.

 

[sand1man]

Thanks again for the info, just wanted to try to make sure before I pull the carb box off