Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Idle adjustment

(1/3) > >>

Paul:
When you adjust the idle on a quadrajet, #17057266 do you want the primarys completely closed? so that the idle speed is adjusted solely by the idle mixture screws?

omaha:
   I would not recommend that kind of set up. I think it is possible to run the carb that way, (and some carbs do run like this, VW Solex PICT 34 is an example) BUT, I think you would have to have some kind of variable air adjustment under the throttle plates. The point is you are mixing a fuel and air "emulsion" with a body of more air. To get it to mix right and have rpm adjustment at idle requires both the air to be adjusted AND the emulsion mixture to be adjustable. Bypass air is  not set up to be adjustable on the Q-jet. (although I have been thinking of this idea??) And, the other problem is what happens to the transfer slots. Usually the portion of the lower slot is exposed while idling and the slot make s a nice somewhat linear transition into the off idle circuit. It all overlaps in kind of a very ingenious design. With the plates closed this would not happen, at least with the stock design.  (long post , sorry it's late. haha) Good luck!

von:
omaha you mentioned the possibilty of adjustable bypass air. IMO that could be very do-able if some sort of small adjustable air valve could be attached to a large manifold vacuum port on the carb. There might be a difficulty in getting a large enough port in some situations, plus it would be unfiltered air. Now if some sort of tiny air filter and air valve could be rigged up it might be a good tuning aid.

TommyK:

--- Quote from: von on April 02, 2013, 03:09:49 AM ---omaha you mentioned the possibilty of adjustable bypass air. IMO that could be very do-able if some sort of small adjustable air valve could be attached to a large manifold vacuum port on the carb. There might be a difficulty in getting a large enough port in some situations, plus it would be unfiltered air. Now if some sort of tiny air filter and air valve could be rigged up it might be a good tuning aid.

--- End quote ---

This is the essence of the Idle-Eze feature on Demon carbs.

omaha:
Yeah, I was thinking of using a ball valve (easy to find and adjustable I would think) with some hose barb fittings and tapping a port right into the manifold somewhere then on the other side of the valve I would run the hose to a fitting on the air filter housing (into the filtered air obviously). The only problems I could think of is how to keep the ball valve from maybe moving on its own. Maybe try and put some kind of set screw in there somewhere after you get it all adjusted up and then when you needed to readjust it, loosen the set screw and reset. Hmmm........???? Might just work.

Navigation

[0] Message Index

[#] Next page