71 Buick LeSabre 350 engine bogging at light acceleration. I would like to know why it stumbles when I accelerate.
The carburetor rebuild and we have a new accelerator pump on there and it is still doing the same thing.
It's hesitating, not bogging. Check the accelerator pump first. With the engine off, look down the primaries of the carburetor. Rapidly open the throttle and look for two strong streams of gasoline. If you don't see two solid streams of fuel, the next thing to check is fuel pressure and volume. If that checks out, then suspect float level. You should also check engine vacuum. A vacuum leak will produce hesitation as well.
Work with the idle mixture and timing first, distributors can loosen and move, stuff wears etc, if the idle mix is off the tip in response won't be crisp. Maybe the pump cup rolled upon installation, or wasn't clipped over the tangs correctly, some of the kits have a cup you have work with a little. I lube them up with WD and check the pump bore b4 installing. If it likes a few more degrees of initial than so be it, give it to it. If there are too many turns in the idle speed screw you will have issues, idle speed comes from the mixture and the timing, the actual speed screw is only for those fine adjustments 95% of the time I always run the float higher than stock from my experience it works better jmo
In situations like this I will usually pull the carb off and do some investigating, dies the pump move clean and smooth, does have a strong stream, is there fuel collected in top of the carb especially over the pump rod. Does the primary rods move smoothly. I've taken apart a lot of "rebuilt" carbs with a primary rod tower that's all knicked up and the bore full of varnish etc. It has to be able to move in the bore to do what it needs to do
Be sure to take the float out to bend it, you don't ever want to push down on the needle , maybe the old ones from days past didn't mind it but the crap we gotta use now will ring out and leak, also be sure to look at the seat, I've seen plenty with burrs on the seat that cause leakage if left there
