I have a Quadrajet 17086004. I was wondering if I am supposed to have a secondary vacuum pulloff. This is going on an 85 LG4. I am not familiar with quadrajets so I have no clue. This is not the carb off the car, but I am trying to get it running for a friend. I was also wondering what makes the secondaries open . The carb seems to lock it out with a piece behind the choke. I am new to quadrajets so I am sorry if I am asking dumb questions. Thanks in advance.

 

The secondaries are locked out by the Choke when cold.

 

So if the choke pulloff doesnt work, will this affect the secondaries? The car the carb came off of was real sickly and the secondaries never opened. I rebuilt the carb and replaced the pulloff. The carb was full of carbon and the pulloff would not work. Could this be why the car felt so weak? I am sorry for asking so many questions, but I am used to fuel injection and I have never worked with a Q-jet.

 

The dashpot controls the opening rate of the secondary air valve. If it was plugged with carbon, I suppose it could prevent the air valve from opening at all.

 

The carb was also missing the little lever on the side of the chohe plate and the linkage. I have replaced them, and adjusted the ckoke the best I can. The carb had the choke plate tied open with a shoestring.

 

Well then, you have a first rate carb on your hands!

Now go to this site's Tech columns and find those on the QJet. They'll show you how to fine tune the QJet and it is dead easy to do. Then you are in for a real performance surprise

 

I plan on upgrading the rods and hangers after I get the car running. I already set the air valve tension according to the article. The carb will eventually go back on my 86 Gran Prix. I am loaning the carb to a friend until he can find one of his own. This has been a learning experience for me. I am still always amazed at the butchers that "repair" cars.

 

I have had this carb on the car for some time now and can't seem to fix one problem. The car starts and idles fine, but it stumbles to the point of stalling when you floor it. The choke is working properly and the car runs like it should. It seems like the secondaries won't open. The ignition system was serviced ( plugs, wires, cap, rotor, and pick-up coil) and the timing is stock. I have played with the AV tension to the point I can do it blindfolded. The plastic peice under the hanger is there and in good shape and all linkages are clean and free. I have no complaints with the carb except this one problem. Please help!

 

It is easy to check the secondaries. Warm up the engine then shut it off and remove the air filter lid. Prop open the Air Valve, then reach under the air cleaner housing and rotate the throttle cam all the way open. Look down the secondary venturi at the throttle plates, do they open? If not, they are locked-out by a part of the choke linkage.

 

I tried what you suggested and mine doesn't open! What causes this and how do I fix it. I read the post last night and checked this morning. I hope I don't have to replace the thermostat, NAPA wants 70 dollars for one. The lockout for the secondaries is just flopping, it has no tension at all.

 

The lockout doesn't have any tension. It is gravity operated. When the choke opens completely, the fast idle cam is supposed to drop down and hold the lockout away from the secondary throttle shaft pin.

Try adjusting the thermostat and/or fast idle cam as necessary to get the lockout to release when the engine is fully warmed. Personally, I remove the thing, because its only purpose is to keep idiots from going WOT while the engine is cold. And, I don't drive like an idiot when the engine is cold.

 

My carb does this from time to time.
When I spray the linkages on the outside of the carb with WD-40, it works fine for about a year. Now I just re-spray it during every oil change.
NOTE: WD-40 is NOT a lubricant; it is a solvent (cleaner) and corrosion inhibiter.

 

I cleaned the choke linkage again and it got a little better. I also tied back the lockout lever. I also noticed a fast idle problem. Could this also be from a misadjusted or weak thermostat. The thermostat still has the rivets in it so I guess it is time to break out the drill. What is the best way to adust the thermostat and fast idle. The rebuild directions are vague at best and show some sort of angle guage. Can I do this without this guage?

 

I get really scientific about choke adjustment.

Thermostat: With the engine stone cold, open the throttle enough to get past the fast idle cam and hold it there (assistant or held open mechanically). Rotate thermostat until choke butterfly releases, then turn it back the other way until it closes. Tighten thermostat screws.

Choke pull-off: Typically adjusted to a certain gap at the top of the choke butterfly, but tweak the adjustment until the engine starts well when cold and doesn't die.

These assume that the choke thermostat is in good operating condition, and the linkage is free of binding.

 

By " past the fast idle cam" do you mean to where fast idle would be off. or to where the ckoke slams shut?

 

yap

 

I thought i'd bring this thread back up because I have the same question as the last one bingo had.

Does the thermostat tuning advice refer to when the engine is *off* and cold? Then hold throttle OPEN enough to be past the fast idle cam (?) then turn thermostat to just barely closed?

I think I over turned my thermostat CCW, it's hard to start (floods) when *warm* starting...
Thanks
-J

 

Engine & ignition key off. You have to open the throttle because the fast idle cam has been down when the engine was last running, and will hold the choke butterfly open until the throttle is opened.

If it starts well when cold as adjusted, but floods when started warm, then you may have a weak thermostat spring.

 

hmm, ok, I can do that, just open the throttle enough for the choke to "snap" shut, then hold it there? Meanwhile, adjust the flap so it's just barely shut eh?
ok, my thermostat (the black piece of plastic) is fairly old (20 years...), if the spring is weak I wouldn't be too surprised.
Thanks! -J

 

I thought you used the notch in the aluminum thermostat housing to align the thermostat spring assembly (what you plug the wire into). I did not know you adjusted (rotated) the spring assembly for your application. I thought it just lined up with the notch and your done.

phil

 

The notch is just there to indicate the factory position. You might need to deviate from it depending on age and climate.