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Aaaahhhhhhhhh!!!!!!!
Need Holley Power valve info!!!
I have had chronic ignition problems for the past week or two. Finally got that fixed, but in the process, experienced a number of backfires thru the carb. Every time a backfire would occur, the car would run worse and worse. I have a Holly 650 double pumper, and I suspect I blew the power valve. What happens now is that the car will start and run but with the following symptoms: Barely idles Sounds a little "off" revs up but will not take any load misses and coughs under load Does this sound like the symptoms of a blown power valve???? HHHEEEELLLLPPPPP!!!!! :( Ed |
It's a cheap fix. Pull it & replace it! :cool:
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Ed,
You didn't let Scott Harrison tune your carb did you? He is famous for his mushroom-cloud backfires!! Rob |
HAHA, No, this is my own personal little fiasco.
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Ed, it is not a fiasco, tuning is a trial and error type deal.
The power valve is cheap, usually if it is damaged, black smoke will be puffing out he pipes and the engine will be loading up. Sounds like you may still have ignition problems. Are all the wires on the right posts and plugs? Is the timing at final in the right range of what it should be? 30 to 36 degrees? Are all the vacuum hoses connected correctly? Just my $0.02 |
Don't lean over it whilst tuning..:LOL:
Bernie |
This really has me bugged. The car has run flawlessly for years.
I am going to double check all the wires again. |
You might want to get a power valve tester to see if yours is really blown:
http://www.jegs.com/cgi-bin/ncommerc...61&prmenbr=361 You'll also need a hand vacuum pump with a reasonably accurate gauge. I know it's a bit pricey, buying a $32 tool to check a $5 part. However, it's nice to be able to check out the fault to see if it's actually a fault, rather than just changing parts and hoping. My 2 cents, FWIW. |
Holley and other manufactures make a kit with a drill bit and brass pill with a ball in it that instals in the bottom of the baseplate to prevent the backfire from reaching the powervalve. It is easy to install and not that expensive.
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The power valve tester is nice, but not really needed. The "tester" will tell you precisely at vacuum the PV will open. If it's a 9.5", then it should open at 9.5".
But if you just want to know if it's "blown", simply "suck" on it! Wrap those lips around that gassy bad boy and see if it holds vacuum! If it does, it's working. |
Quote:
Especially if you are smoking**) :LOL: |
While you are in there I would take the whole thing apart and blow out all the orfices. Also check your fuel filters. I assume you have one between the tank and pump and one between the pump and carb. Also blow out your pressure regulator.
Roscoe |
Well folks, I have the answer. The problem was not fuel related with the power valve as suspected. I knew that I either replaced or bypassed every component in the ignition so I felt that ignition was OK. Plus I knew that during the problem time I experienced a number of backfires thru the carb, so I figured that I needed to look into the power valve.
BUT, . . . . Last night I found that the little iron "starwheel" that is in the Duraspark distributor and triggers the magnetic pickup was spinning on the shaft. The little rollpin that is supposed to hold it in in place was gone. Not sure how or why. I had taken the starwheel and pickup off earlier during the initial problems, and I know I put the pin in there, but it was gone and so my timing was all over the place. So that is the end of Ed's enigmatic saga!! Life is good again. No more laying in bed at night sweating and trembling :LOL: Thanks to everyone for your help. Ed |
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