Vehicle is a 79 dodge half ton, 318 with a two barrel. I rebuilt the carb, replaced plugs, wires, yada yada. It idles good, cruises good, accels good. The only issue is a stumble on tip-in throttle. I was planning on ajusting the accelerator pump linkage tonight to make it cone in a little earlier. Anything else i shoyld be looking for?
Is this the (I think) stock Carter 2 bbl? The one with the single big opening on top and two butterflies? I have had a few of those. Decent, simple carbs.
Is there slop in the throttle shaft? I have seen these where there develops an air leak in the throttle shaft, so the idle screw has to be turned down to the point where the butterflies are more closed than they ought to be at idle. Then, on tip-in, the enrichment doesn't work quite as quickly as it ought to, and you get a stumble.
You may be able to rebush the carburetor body to eliminate slop in the throttle shaft.
Alternatively, although obviously more money, a 4 bbl manifold and a new Demon 625 cfm 4 bbl carb is the hot ticket. I put one on a 383 Mopar and my wife's 350 Chevy, and it's the best carburetor for a street car I've yet encountered.
Is the stumble just at idle, or while cruising?
If just at idle, it's likely your idle adjustment. If you set your idle for highest vacuum, you could be experiencing puddling where little drops of gasoline are puddling in the intake manifold due to too much vacuum. You'll know this is the case if you make the adjustment you're talking about and the problem gets worse.
In reply to Willis :
Just at idle. Its only noticeable when pressing the gas pedal leaving from a stop
I'd play with the accelerator pump. As long as it runs OK otherwise.
Look down the carb throat with the engine off and be sure that you're getting a nice big squirt from the accelerator pump when you open the throttle.
If you're not, you have a plugged passage some where or a missing check ball.
If you are getting a nice big squirt, you may have an ignition problem, try a little more initial advance.
Make sure your vacuum advance can is hooked up to ported vacuum and that it's working properly.
Lots of carburetor problems are igntion problems.
Yep acc pump. I call it stumble on tip in. Try adjusting it so that it pumps more and / or sooner as you "tip in" to the throttle.
Check the timing
dean1484 said:Yep acc pump. I call it stumble on tip in. Try adjusting it so that it pumps more and / or sooner as you "tip in" to the throttle.
This did it. Thanks for the help.
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