A friend of mine had a local guy try to rebuild his 71 GTO 455 Quadrajet # 7043262. He asked me if I could help and he shipped me the carb, it was in pieces. No problem with the rebuild except that when I got it the triangle shaped clip and the idle air bleed screw were removed. There is no spec for the idle air bleed screw, it was set when the carb was manufactured and is not supposed to be touched. It was removed from carb when I got it, does any one have any idea how many turns out from seated this screw should be? Any kind of ballpark adjustment would be appreciated. Thanks in advance. Please Help!
Dean Oliver at "Deano's Carbs." is a good source.
Also, on Class Racer, Danny Ashley. Danny is retired but still post on that site.
Its always been about 1-1/2 to 2 turns out as a base setting for just about any carb for idle adjustment.
I rebuilt a lot of Q-Jets and raced them...
They are great street carbs but can give you fits when drag raced.....
Stumbles and bogs are what they do a lot and pinpointing the problem is the difficult part....
I had a '67 GTO around 1970 and spent hours tuning the Q-jet for the best stomp it to the floor on the street performance....
The later years they made them tamper proof on the idle screws......emissions issues.
Thanks for the info, I will call them tommorow
Thanks for the reply,but I am not talking about the idle mixture screws. On some big block Pontiac carburetors there is an actual screw underneath a triangle clip that is not supposed to be removed. It is set when the carb is manufactured and then a "non removable clip" is placed over it When I received the carb, the clip and screw were removed. this is an adjustment in the actual idle air bleed tube, it adjusts the amount of air that is mixed with fuel in the idle circuit.
That is not ringing any bells for me.
My experience is mostly with earlier model carbs
If I saw it in front of me I might recall that part of the carb better.
The rebuild kits usually had a lot of diagram sheets and info on specs for each carb. to make it back to as built by the OEM
He is talking about the off-idle adjustment screw that comes factory calibrated.. I never touched the adjustment when i did a bench job.. after all the years, i couldn't tell ya how many i had tossed or kept for spare parts..
Like in figure 5.
Thanks for trying and responding. I read your posts all the time when you are helping people with there Onan gensets. I have a 12500 diesel generator, it is a 2005 model and has worked very well with just maintenence. There is no spec published for this adjustment. It was set on a flow bench when manufactured then the anti temper clip was put on. The only place it is even mentioned is in the factory Quadrajet Service Manual, and then only mentioned in the theory section. It is not shown even in the illustrated breakdown.
afrer reading the instructions i would make a wag and go 1 1/2 turns and try itThis message has been edited. Last edited by: rusty,
honesty is the best policy,insanity is a better deffense
1.036, 6.16@ 224
While it doesn't appear the above would help the OP, I recently rebuilt a 1V Rochester on a '63 C10 for a neighbor. The instructions, maybe unique to the particular seller on eBay, were beyond excellent and had everything one needed for a standard rebuild. You can imagine my delight.
Illegitimi non carborundum
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