Why is it skipping???????
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Elder User
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From: Rome, GA
Why is it skipping???????
I have a skip in my 460. After I put my tunnel ram on I found out that my fuel pump is not big enough. It ran fine until I turned it up hard and it started running out of fuel. It popped back several times and started running very rough. I changed the plugs in it, the back plugs on each side were black 3,4 and 7,8. The front plugs 1,2 and 5,6 looked good though. I replaced all of them and it still skips very bad. There is no valve train noise or other engine noise. It just skips like a bad plug. I thought I might have blown a power valve in one of the carbs, I dont know. What could be the problem? Any help would be apreciated.
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Joined: Nov 2001
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From: Escondido, CA
The blown power valve may explain the back spark plugs being black. If your carbs are newer then 2001 then a power valve saver was installed. Check the inside of the distibutor cap for carbon tracks it can misfire one of the plugs. If you find nothing there, spray each tube on your headers with water to see which cylinder isn't firing. It's a lot safer then pulling the plug wires off one at a time when it's running. Also you might have a vacuum leak on one of the intake ports. Spray the intake gasket with ether or starting fuid, if the RPM kicks up you found a leak.
Last edited by airharley; Mar 17, 2007 at 08:26 PM. Reason: updates
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Elder User
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From: Rome, GA
Originally Posted by airharley
The blown power valve may explain the back spark plugs being black. If your carbs are newer then 2001 then a power valve saver was installed. Check the inside of the distibutor cap for carbon tracks it can misfire one of the plugs. If you find nothing there, spray each tube on your headers with water to see which cylinder isn't firing. It's a lot safer then pulling the plug wires off one at a time when it's running. Also you might have a vacuum leak on one of the intake ports. Spray the intake gasket with ether or starting fuid, if the RPM kicks up you found a leak.
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Elder User
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From: Rome, GA
I checked all the manifold bolts they were tight. My carb bolts were also tight. I pulled the valve covers and all the push rods and rockers look good. I didnt crank the motor with the covers off. Did I need to do a visual of these while running? (makes such a mess) Also the engine is pulling around a 6 on the vaccuum gauge. I am still stumped. I still think I could have a power valve problem.
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Elder User
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From: Rome, GA
Got an e-mail reply from Holley Tech. They said it sounded like a blown power valve to them. I have power valve block offs coming. Do I need to go up onjet size? If so how much of an increase?
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From: Union, Washington
Originally Posted by bhardy501
Got an e-mail reply from Holley Tech. They said it sounded like a blown power valve to them. I have power valve block offs coming. Do I need to go up onjet size? If so how much of an increase?
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From: Rome, GA
These are brand new Holleys I thought they were supposed to have PV protectors from the factory. Holley Tech advised that they thought it was a blown power valve. I knew I was going to have to change the power valves out any way. My cam doesnt produce enough vac. for the factory valves.
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Post Fiend
Joined: Mar 2004
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From: Union, Washington
Originally Posted by bhardy501
These are brand new Holleys I thought they were supposed to have PV protectors from the factory. Holley Tech advised that they thought it was a blown power valve. I knew I was going to have to change the power valves out any way. My cam doesnt produce enough vac. for the factory valves.
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From: Rome, GA
Boy I feel like a real dumb a&%. I found the source of the rough Idle/skipping problem. The choke flap on the rear carb was shut and I didnt know it. I changed the power valves to block off plugs and changed the jets up 2 sizes. It runs good again and isnt to rich anymore. Thanks for all the suggestions.