69 quadra jet choke issue

[Jim M.]

My Rochester Quadra jet choke closes properly when the accelerator is tapped and opens about a quarter when started however if I tap the accelerator after it starts it imediately takes the choke off and unless I keep my foot on the accelerator, it will die. I keep my foot on it or start drivng it until it warms up and then it idles just fine. The choke shouldn't come off that quick should it? And shouldn't the choke gradually come off as it warms up so that it won't die?

[Terry M.]

Re: 69 quadra jet choke issue

My Rochester Quadra jet choke closes properly when the accelerator is tapped and opens about a quarter when started however if I tap the accelerator after it starts it imediately takes the choke off and unless I keep my foot on the accelerator, it will die. I keep my foot on it or start drivng it until it warms up and then it idles just fine.

1)The choke shouldn't come off that quick should it?
2)And shouldn't the choke gradually come off as it warms up so that it won't die?

[Jim M.]

Re: 69 quadra jet choke issue

Thanks Terry, I don't have a the Chevrolet Service Manual for my 69 but I should get one. Jim

[Terry M.]

Re: 69 quadra jet choke issue

Those "funny papers" also come as part of a carburetor rebuild kit.

[Jim M.]

Re: 69 quadra jet choke issue

Terry, If I need a carb rebuild, then I'm going to take it to someone who knows what they're doing. Guess I was hoping it was an adjustment type thing. I don't think there are any parts missing and everything is hooked up. So my next step is to get a CSM and try adjusting myself and if that fails, then fine a carb person. To start with I was just hoping to find out whether the symtoms I am experiencing with the car were normal or not and it sounds like the choke should pull off gradually and not all at once right after it starts. Jim

[Terry M.]

[Joe L.]

Re: 69 quadra jet choke issue

OK, I'll try:

1) The choke plate comes off that quickly. There is a vacuum diaphragm called the choke pull-off (on the left front of the carb) that pulls the choke plate open as soon as the engine begins to run. It should pull the plate all the way open.

2) The part of the choke (the part that is the step "cam" on the passenger side of the carburetor) should come off gradually. This is the part that controls engine speed. This part is controlled by the choke stove on the intake, and it is the part that should move slightly with each "blip" of the throttle. Depending on your ambient temperature this step cam may, or may not operate gradually. If it is real hot out (say 80* F or higher) it may just make one jump and it is done.

Each of the above can be adjusted separately. And it sounds to me from this distance like the adjustment(s) may be off. Of course that is just one person’s opinion.

The CSM will have the values for those adjustments. They can be done using the tachometer in the car, but you will find it a lot easier if you have an electronic tachometer you can hook up to the coil. These are available (or used to be, I haven’t looked in years) from the automotive department at Sears among other places. The CSM is available from the NCRS store at the radio button at the top of the page.

Terry and Jim------


The choke pull-off control is one of the few parts of the carb still available. It's discontinued through the GM parts system but it should still be available through the Delco parts system (at least, for awhile). It's GM #7038239. However, the color of the plastic body will likely not be the same as original, but it will be fully functional.

The fast idle cam on these 1969 Q-Jets was made of a plastic material. In time, these crack and generally deteriorate. These are long-since GM discontinued.

[Clem Z.]

Re: 69 quadra jet choke issue

The fast idle cam on these 1969 Q-Jets was made of a plastic material. In time, these crack and generally deteriorate. These are long-since GM discontinued.[/quote]
if this cam looses it metal weight the fan wash can blow the cam back on fast idle after driving down the road and you come to a stop.

[Clem Z.]

Re: 69 quadra jet choke issue

The fast idle cam on these 1969 Q-Jets was made of a plastic material. In time, these crack and generally deteriorate. These are long-since GM discontinued.

if this cam looses it metal weight the fan wash can blow the cam back on fast idle after driving down the road and you come to a stop.[/quote]
here is a metal replacement fast idle cam to replace the plastic one. don't think it will pass the NCRS police. item # 85-145 http://www.carburetion.com/quadrajet.asp

[Dennis D.]

Re: 69 quadra jet choke issue

Don't know why I have this pic, or the numbering, but maybe it will give a visual to the discussion

[Terry M.]

Re: 69 quadra jet choke issue

Don't know why I have this pic, or the numbering, but maybe it will give a visual to the discussion

Nice choke pull off.

[Jim M.]

Re: 69 quadra jet choke issue

On a related topic, I noticed that in my book it says that the fast idle should be 2400 RPM. I'm guessing that's the start up RPM with the choke on. Doesn't that sound pretty high? Seems like the fast idle on a small block should some what less then that. Also, when my 350/350 is warmed up it idles at about 700 to 800, is that about right?

[Clem Z.]

Re: 69 quadra jet choke issue

On a related topic, I noticed that in my book it says that the fast idle should be 2400 RPM. I'm guessing that's the start up RPM with the choke on. Doesn't that sound pretty high? Seems like the fast idle on a small block should some what less then that. Also, when my 350/350 is warmed up it idles at about 700 to 800, is that about right?

the fast idle speed shown in GM service manuals are with a warmed up engine with the fast idle cam set on the fastest idle step