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Author Topic:   blocking power valves
Dirt Roller

Total posts: 25
posted April 08, 2001 05:10 PM
looking for information on blocking the power valves on an old BG meth. carb. mainly want to know effects (good or bad) and how much to increase the jet size.

Dirt Maniac

Total posts: 168
posted April 08, 2001 09:37 PM
I think you go up about 4 jet sizes but the car will run extremely rich at idle and low rpm's. Why would you want to get rid of the power valve.

Dirt Moderator

Total posts: 67
posted April 08, 2001 10:14 PM
go up 6 to 8 jet sizes,i agree why remove power valve,you'll have to keep clearing out the motor...use more fuel

Dirt Full Roller

Total posts: 57
posted April 11, 2001 09:45 AM
FWIW, you should never have to block off the power valve circuit if the carb is tuned properly for the application. Everyone else is right, here, that you'll have to add several jet sizes to attempt to compensate for the lack of fuel.
And with an alky motor, missing the jetting and leaning her out can be a bad thing. 'Course, washing down the cylinders with alky due to having to run so rich at idle is not good for either the rings OR the oil, and consequently, every part the oil protects, too.
I'd tune the carb with the p/v's left functional.

Any assistance I can offer, just ask, ok?

Hope that helps,
Kinetic Performance

[This message has been edited by KPLugnut (edited April 11, 2001).]

Dirt Full Roller

Total posts: 48
posted April 11, 2001 04:34 PM
I'm using an alky carb built by a big name drag racer. He does not use a power valve in his carbs. While doing a look-see while cleaning it this spring, I couldnt figure out what a power valve could do on this carb, because there are no holes/pathways or circuts that it could affect. The carb appears to br a standard Holley, sans the obvious grinding. So perhaps there is a carb builders trade secert with these power valves. My jets are 115 and up.

Dirt Roller

Total posts: 25
posted April 12, 2001 06:52 PM
thanks for the info. i had borrowed a carb. at the track that had the valve removed and felt like it was very responsive. of course it was built by a commercial builder. it may have had other work done to it. i think i will leave the valves in for now.

Dirt Freak

Total posts: 213
posted April 12, 2001 11:25 PM
i once had a problem with a carb, 2 barrel on gas that was reccomended to me to remove the power valve and go up 6-10 jets sizes. the problem was it acted like i had a fuel or ignition miss . after switching the entire ignition system and carbs twice with the same problem , i removed the valve and jetted up and the problem went away. the only way to find out if it will help or hurt is to try with and without. the carb was more responsive after removing the valve.
richard w

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