Q-jet help

[vetteboy86]

I have a problem with the carb on my Pontiac Trans Am. I figured most of you would know something about these carbs. I was trying to adjust the tension on the secondary air valves. I suspected these to have not enough resistance. I was experiencing a bog, and a rich condition when the car was under a load. But know my problem is getting the car driveable again. I was adjusting the tension screw on the passenger side of the carb. The valves did stiffen as I turned the screw, however I think I hit the end point. I heard a click, and now the air valves just drop open. I guess there is a spring inside there. How can I fix this problem. I am pretty much new to these carbs, so any suggestions would be appreciated. I hope you guys can help me out, and possibly someone else with a Q-jet issue. I didn't think I would get too much help from the C4 guys.

Thanks again

Craig

 

[Bill75]

Hello Craig,
I just did some work on my Q-Jet and I have Doug Roe's book. I looked in it for some explination of the secondary spring you're refering to. He mentions it in the "how it works" section but doesn't tell how to replace/repair it that I've seen yet. There's some pretty sharp carb guys on here that helped me out, I'm sure they'll pop in. Sorry I can't helpmore but I'll read a little more.

When I took mine apart I found that one of the fuel feed tubes for the secondaries had vibrated loose and was laying inside the fuel bowl. It would bog for sure when the secondaries opened, sometimes backfired a little from the lean condition.

Bill

 

[vetteboy86]

Bill,

Thank you for the reply. I bought a haynes book but it is very general. I dont really think I can tackle a job with that. I am the type of person that would like to fix it myself, that way I know a little more about it. I have been trying to get a few guys to come over and look at it. I am going to poke around on it tomorrow. I hope some more guys chime in, until then I look forward to hearing from you.

Thanks again

Craig

 

[69_coupe]

It is a pin attached to the adjusting screw, the spring is hooked up on this pin.
Sometimes the hook on the spring just fall off the pin. You will find it if you look under the adjusting screw, just beside the small screw that locks the adjusting screw. The other end of the spring is fastened to the shaft for the air valves. To change the spring if it's broken; pull out the pin from the adjusting screw, unscrew the small lock screw and pull the adjusting screw out, and then reverse action. (you need small hands)

 

[vetteboy86]

69 Coupe,

I am a little confused about the pin you are talking about. I am however going to work on it tomorrow. So if I look under where that adjustiing screw is I should see a pin? Okay I know where the lock screw is, it is an allen screw right. Screw that allen screw out and the adjusting screw should come out. At this point I can re-attach the spring, or put a new one on if the other is broken. Once I attach the spring, put the adjustment screw in, then lock it with the allen screw. I hope I have this down at least in my mind. Until I actually work on the car I am going to go over this in my mind. I am not that good with carbs.

Thanks for the reply.

Craig

 

[69_coupe]

The pin is pressed into a hole in the adjusting screw, like a lever working on the spring.

 

[vetteboy86]

69 coupe

I really appreciate your help. I am going to attempt to do this. However do you think it would be less painful to do it off the car. I am a big boy and dont have little hands like you said. I think when it is off the car things might be alot easier. I could probably have it off the car in a half hour or so.

Thanks again

Craig

 

[MMM]

The pin is actually pressed into the air valve shaft. The tension spring is a coil with a "u" shaped hook on the end that fits around the pin. The spring adjustment has set screw, placed at 90 degrees to the tension adjustment screw to keep the tension adjustment screw from turning. You probably know this all ready, but just to make sure. I forget off the top of my head which way the tension spring adjustment needs to be turned to tighten. It sounds as if the set screw has backed off on your carb. So find the set screw, make sure it is loose, then tighten the adjusting screw. For now use one turn after the spring makes contact with the spring. If you e-mail me directly and give me the carb #, I can look up the original factory tension adjustment. I have all of the original Delco-Rochester books on Q-Jets (about 2 feet thick).

Mike

 

[MMM]

Oh yes, forgot to tell you to make sure you retighten the set screw after adjusting the tension!

M

 

[vetteboy86]

Actually what happened was I turned the adjustment screw too tight, and it broke the spring. After inspection of the spring I realized that there must have been a week point where the spring went around the pin.

I appreciate all the responses. Without them I wouldn't have had such a good start on this problem. I took the carb off the car. It made things alot easier. I would have never been able to do it on the car. I was at it for about an hour when finally the spring just slid in.

Thanks again 69 coupe, and MMM. I owe you both one.

Craig