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Idle Adj Screw on Quadrajet?

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04-29-2005, 04:39 PM
dogill
Idle Adj Screw on Quadrajet?
Just got home from a 400 mi round trip. Continue to get exceptionally good gas milage. Barth ran good 'cept for one minor deal.
I think the idle screw has vibrated loose a little. Had trouble with engine dying at stop signs a few times. Not an over-heated problem.
Anyone have a pic of the Quad or a good discription of where it is?

Thanks,
Don
04-29-2005, 04:56 PM
hilarlee
Hi Don, I'd be surprised if your idle screw was loose. Have you checked all your vacumn hoses to make sure they're all attached?

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Larry and Heidi from CA

04-30-2005, 12:00 PM
dogill
quote:
Originally posted by hilarlee:
Hi Don, I'd be surprised if your idle screw was loose. Have you checked all your vacumn hoses to make sure they're all attached?



No, but excellent idea. I disconnected a few when replacing the fuel filter and may have overlooked an important connection.

On the 454, what should the average idle RPM be on a slightly warmed up engine? I don't think my tach is real accurate. My normal idle RPM has been indicating 1000 but lately, it wants to drop to around 700 and will sometimes die at this point. For reference, at 60 MPH, I taching about 3500 RPM.

Thanks,
Don in Dixie
'84 Regal
04-30-2005, 03:41 PM
Gunner
"lately, it wants to drop to around 700 and will sometimes die at this point."

Sounds like vacuum to me, too; not idle setting.
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"You are what you drive" - Clint Eastwood

[This message has been edited by Gunner (edited April 30, 2005).]
04-30-2005, 04:56 PM
Gunner
Another thought: high mileage QJs are notorious for leaking air (sucking) through the butterfly valve shaft where it goes through the body; it is erratic (random)and the effect is the same as a vacuum leak . Remove the air cleaner and wiggle the shaft and see if it moves in the body.

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"You are what you drive" - Clint Eastwood
04-30-2005, 08:53 PM
olroy
FWIW - Went up & exercised the beast this morning - 454 in a '90 Regal.

With a tachometer graduated in 200 RPM increments, everything is calculated as "about," but in neutral it idles at about 900, drops to around 700 in gear, and loses another 25-50 RPM with the a/c xompressor engaged. Haven't had any problem with stalling when it is thoroughly warm, w/ or w/o a/c.
05-03-2005, 05:31 PM
bill h
Good advice on vacuum hoses. I would advise replacing all of them with the red silicone hoses from NAPA. They are by far the best for the high heat environment in RVs.

Also, use a little carb spray on the external carb and choke linkage and heat riser. (your heat riser IS free, isn't it?)

And throw a bottle of Red Line fuel system cleaner. It is by far the best. It may even make your genset start and run better.

A new throttle return spring can help, too. Some springs are double, with a coil within a coil. Often a failure of one of the coils will go undetected.

It is also possible that your centrifugal advance is not returning fully to the stops. Remove the dist cap and check for red dust. It there is any, blow it out and lubricate the weights and fulcrums and pivots. Red dust will cause a high voltage arc and blow the module or cause a crack in the cap.

Gunner's point on an air leak at the throttle shaft is a good one. Squirting thick engine oil at the shaft bore is a good test. If the engine speed changes, or the oil is obviously sucked in, there is a leak. Some mechs squirt gasoline there as a test, too.
05-03-2005, 10:15 PM
timnlana
How do I adjust the Idel screws? I have a rebuilt card just back in the Barth and little idea of what to do.
05-30-2005, 11:14 PM
dogill
Hey Guys,

I've been on the go in my Barth lately and not close to a computer. I just wanted to stop by and let you know that you were right, as usual.
My problem was a vacum hose that took all of 10 seconds to fix.
She's running very well these days and I'm really ejoying her.

Thanks again,
dixie dog