hey guys! i have a 72' dart with a 225 and holly 1920. ran fine last evening on the way home from work. today it it is ROUGH! thought it was just cold but that ain't it. big power drop, uneven at idle and cruise, stuttering almost to the point of konking out, and smells very rich. now i only have and tools, no test equipment, but i can probably get ahold of some. i am hoping that you guys might be able to help out as my manual just overwhelms me.
thanks'
matty

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numbskull with auto mechanics

Sounds like the power valve might've fallen apart inside the carb, or its vacuum actuator diaphragm might've ruptured. I've seen both failures. The power valve (Holley calls "Economizer") is a spring loaded ball bearing against a brass seat ring staked into the end of the metering block. There is a nylon bellcrank-arm hinged to the end of the metering block. The actuator, which is installed from above under that 3-screw cover atop the carb bowl, has a stem that rides on the hinged arm. When vacuum is applied to the actuator, the stem lifts up and the spring-loaded power valve closes. When vacuum drops, the spring-loaded stem drops, depressing the hinged arm and opening the power valve.

If the seat ring comes unstaked, the ring, the ball and its spring land on the bottom of the carb bowl and the power valve is open (WAY OPEN!) all the time.

If the vacuum diaphragm in the actuator tears, the stem (being spring-loaded) drops and the power valve is open all the time.

Another possibility is a soaked/sunk float. Another is a stuck/dirty inlet needle and seat.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Choke stuck almost shut?

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Official Cookie and Mater Tormentor.

Timing Chain Jump?

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64 Dart 170 /6

So it seems that a good place to start would be to get the carb off and rebuild it? I'm up to it if it makes sence, been there done that on a 62 nova. ???

And thank you all for the swift help so far.

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numbskull with auto mechanics

That would be a good step if it's been awhile since the carb was gone through, yes. (I just noticed you're in Eugene—that's where I had the power valve fall apart on a Holley carb in my '65 when I lived there a decade ago. Maybe you drove over the same pothole!)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

that is the almost the exact same thing that happened to me, i was racing a friend and i knew he would be me but after that race my dart never ran good after that i'll have to check out my carb but i dont know if i'm gonna bother fixing it cause i'm looking at a 4bbl upgrade

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Cuda Progress
The dart as it sits now

apperantlyly, the kit for a holly 1920 # R-7611B is obscure round here. Plenty ending with an "A" . One place had it for just over $30. Wich is about $29 more than I have till payday.
So I decided to clean it out with Gunk just for the hell of it, but then I noticed that the ground from the battery was in the fan zone. Sure enough it was getting munch.
I secured it back to safety. continued to clean the carb out. Started it, warmed it, let the gunk burn out and drove it. Major symptoms are gone budoes'ntnt run quite as well as it did before, lacks the pull and smoothness on accelerationdosn't't threat choking out anymore though.
And it still smells rich. Have to check it out more.
But does the ground wire thing seem like a probablcuasese for really nasty operation?

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numbskull with auto mechanics

NAPA on 11th Ave ought to have an Echlin 2-5461 kit for about $20 for you.

Good job fixing the ground wire, that's important, but no, I don't think that was the cause.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I had a motor scooter at work start acting up like that. I tried to get first shift to get the mechanics to look at it. They said it needed water in the batteries. That didn't fix the problem. I eventually noticed a broken off wire under the seat, which I fixed.

Sounds like those mechanics needed more water in their bongs...

Lou

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Home of Slant6-powered fun machines since 1988