Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

TA olds 403 carb needs tuning help

<< < (2/3) > >>

Ethan1:

--- Quote from: EvelBist on February 08, 2013, 11:34:58 AM ---I really wish I knew the sizes. But I am certain its stock. From poking around on the net, I think they are #75??? jets? I dont know the tube dimensions.

Anyhow, it runs better if I turn out the screws a lot farther than 3, but it doesnt seem to get any better after about 3 turns out ... maybe i need more fuel at idle?

--- End quote ---

 Stock jets for your carb were #73. :)

Cliff Ruggles:
Idle bypass air is used to keep the throttle angle low with big cams/low vacuum at idle.  It adds additional air (controlled vacuum leak) and the idle system needs to have enough fuel to the mixture screws to compensate.  I would recommend larger idle tubes and opening up the down channel restrictions for what you are doing.  This will help the situation.  The bypass air holes may be fine as is.  If you can't get the idle speed low enough, they will need to be blocked, which is very easy to do.....Cliff

EvelBist:
Thanks for the jet size Ethan  ;)

How can I tell what size idle tubes I currently have? I can open up the down channel restrictions using the procedure in the book - right? How much bigger? Is there a recipe I might follow in the book? I am only looking to make the car run smoothly for cruising, not a tire shredder  :P

EvelBist:
Does anyone know what those stock idle tube sizes are or where they can be looked up?

Ethan1:
 Usually you have to measure the size of the orifice, but, most stock Qjet's came with .031-.033 sized idle tubes. Unless they have been modified already.

Navigation

[0] Message Index

[#] Next page

[*] Previous page