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-   -   Qjet idle rich. (https://classracer.com/classforum/showthread.php?t=68066)

HandOverFist 10-31-2017 12:04 AM

Re: Qjet idle rich.
 
Quote:

Originally Posted by richie 2 (Post 548784)
a huge vacum leak will cause it to be rich? I thought I would make it lean...

Yes, lean in most cases. It would be hell to get any stable idle and would have to open the butterflies a huge amount just to keep it running. I finally put an O2 sensor on mine this year...no more guessing what it really wants.

Hacksaw 10-31-2017 08:14 AM

Re: Qjet idle rich.
 
Quote:

Originally Posted by richie 2 (Post 548784)
a huge vacum leak will cause it to be rich? I thought I would make it lean...

Just close off the choke area with your hand with the engine running at idle. Vary the amount of air that can enter the carb until it will run relatively smooth. If you restricted most of the incoming air, look for a vacuum leak or if it runs worse with any amount of air blockage, you are over rich. Don't test with a stone cold engine.

john billups 10-31-2017 02:25 PM

Re: Qjet idle rich.
 
Bingo... I have Idle... found a plug may of come out of the choke vac. port. I also changed the gasket between the body and base. The thing is the carb worked well for 3 season's then went bad, so I was hopping it was a small thing and it was. thanks to all with you input. Often it the thing right in front of your face.

nhramnl 11-10-2017 09:19 AM

Re: Qjet idle rich.
 
This is one of the reasons this forum is so valuable. Racers helping fellow racers, and a thousand years combined experience. In some ways the Internet has been a pain for society, but when it's used for good, it's awesome. Glad you found your problem.

Dwight Southerland 11-10-2017 09:20 AM

Re: Qjet idle rich.
 
Quote:

Originally Posted by nhramnl (Post 549474)
This is one of the reasons this forum is so valuable. Racers helping fellow racers, and a thousand years combined experience. In some ways the Internet has been a pain for society, but when it's used for good, it's awesome. Glad you found your problem.

x2 :)

richie 2 11-10-2017 09:29 AM

Re: Qjet idle rich.
 
now my fresh rebuild is rich...I mean way rich. only thing I didn't do was to repair the well plugs. im swapping in a gm distributor too as I believe our import unit might not even be providing enough spark to fire the mixture...the carb might be just fine...

Hacksaw 11-10-2017 10:23 AM

Re: Qjet idle rich.
 
With the primary rods removed you must block off the plunger well and reduce main jets, to like a pair of 66's. When the well plugs seep it has little effect when the engine is running. It's when it sits, it will drain the fuel bowl.

Ed Wright 11-10-2017 11:56 PM

Re: Qjet idle rich.
 
Richie is correct. Vacuum leaks cause lean issues.
Throttle blades open too far allow fuel to be pulled from the boosters. Will cause very rich conditions. 1/4" float level should be fine. If you have not drilled the primary throttle blades, you likely have the idle speed screw run in too far, opening the throttle blades too far. Pull it, flip it over, the throttle blades should not be above the idle fuel slots in the base plate. Drilling air holes in the throttle blades is always needed with much of a cam, to prevent having to open the throttle blades far enough to pull fuel from the boosters.
Just look down in the primaries with it idling. Top of the throttle blades should be dry, with nothing coming out of the boosters.
Good luck.

Kevin Panzino 11-11-2017 02:42 PM

Re: Qjet idle rich.
 
Also ensure the secondary blades are fully closed and the hanger allows the secondary rods to seat down in the taper. Many times when a carb is converted to "non-progressive" secondary opening, if the linkage isnt just right, the secondaries will stay cracked open, and just pull the air valve open a bit at idle, lifting the secondary rods out of the tapered seat section and it will pull fuel from the secondary tubes and be crazy rich.


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