quadrajet problem

[44070dart]

have a quadrajet on a small block .. when the engine is up to temp if I put my hand over primaries or choke the engine it runs faster .. the idle is terrible, choke on or off ..it runs well above 1000 rpm's but idles terrible or not at all .. tried adjusting idle mixture screws to no avail, will run faster or slower as screws are moved but idles poorly.. all vacuum lines are fastened and plugged.. timing is correct..fuel filter changed.. firing order checked ..dist. cap, wires and rotor new

 

[khryslerkid]

Sounds like a vacuum leak somewhere. Safest thing to spray around intake manifold and carb base is water. Light spritz with a spray bottle. Take a chance with carb cleaner, has faster results but it is flammable.

 

[44070dart]

thanks, I'll do some spraying tomorrow ..I don't hear any whistling noise anywhere but my hearing isn't what it used to be ..I'll start at the carb base

 

[bm02tj]

check position of butterfly as may not be letting you use idle circuit
if open to much may need to inlarge idle hole in butterfly

 

[69L48Z27]

Q-jet? Factory or?

Sounds like a vacuum leak somewhere like Kkid said. Do you have any pics you can post?

 

[PurpleBeeper]

Yes, that is a typical sign of a vacuum leak. It could be:

1. internal to the carburetor itself (not very likely)
2. carburetor base plate gasket
3, any number of vacuum hoses that run to the carburetor
4. intake manifold gasket (where it bolts to the heads)
5. PCV valve stuck open
6. etc...... basically ANY vacuum leak ANYWHERE would cause what you're seeing

 

[44070dart]

Q-jet? Factory or?

Sounds like a vacuum leak somewhere like Kkid said. Do you have any pics you can post?

Q-jet but it's a Buick GS not Mopar.... PCV, checked the connection but didn't think about it getting stuck open ..will replace .. already changed the vac. hoses ..will do some spraying today ..thanks

 

[44070dart]

Sprayed ... carb base picked up couple hundred RPM"S.. PCV base, again jumped up ..intake sprayed didn't do anything.. pull carb as soon as weather gives me a break .. clean out PCV opening and replace it. Hope carb base isn't warped ..I know it happens when people over tighten them.

 

[69L48Z27]

Q-jet but it's a Buick GS not Mopar.... PCV, checked the connection but didn't think about it getting stuck open ..will replace .. already changed the vac. hoses ..will do some spraying today ..thanks

Okay, got it.

What year? If it has the heat cross over slot make sure you have the metal gasket that closes it off to the carb.

 

[44070dart]

it's a 72, .. don't think Buick used the slot manifold, but I'll keep it in mind thanks

 

[SublimeSixpack]

There's a chance that the throttle shafts bores are worn causing a vacuum leak. They can be drilled and re-bushed by a good carb guy.

 

[44070dart]

> replaced throttle plate & shaft <.. took it in to old school master that a friend of a friend knew and he found time to do it .. he is 88 years old ..I had the pleasure of sitting with him while he did the carb, the man has some stories .... wish I had brought a video camera to catch his stories as his old hands worked on it ...great couple hours for a youngster (68) like me .. thanks for input

 

[Photon440]

What was the problem with the throttle plate and shaft?

 

[44070dart]

Yeah shaft and one of the plates was worn .. carb has been around for a while, but it original to the car I think

 

[maxwedgechar]

I thought you were running a mid to late Eighties truck 360. They had Q-Jets (Barf) because it was about that time that Carter went into the dumpster.

 

[44070dart]

Nah, its a Rochester on a 350 Buick GS.. actually I don't think its a bad carb.. pretty simple design, a little economy on primaries, and big secondaries.. it's just old ...like me