The Stovebolt Site Forums The Shop Area Engine Shop 235 w/ rochester BC carb keeps dying at stops

Hi, I'm new here but have read many posts as a non-member. I figure this is the best place on the net for help with my 1958 Chevy Delray. It has a 235 w/ a rochester BC carb and 38k original miles.

My problem and question for the forum is that when I'm driving and come to a quick stop or make a strong left turn, the car dies. It will start right up and idle fine. I have advanced the timing by ear and set the idle fuel screw to highest rpm. Everything seems right on. The plugs are a nice light tan and power delivery is smooth, strong, and linear.

My float is set at 1-14/32 and drop at 1-23/32. I know spec is 1-9/32 to 1-3/4 but the idle fuel screw would not work at that float level. Right now, my idle fuel screw is about 1.5 turns out from seated. I keep thinking it has to do with my fuel level, but I don't know what else to check.

Any help would be greatly appreciated.

Only thing that has come to mind is that I haven't check the matting surfaces for straitness. I think it has to do with the fuel heading to the front of the bowl and to the right that causes the engine to kill. So maybe the gasket is not sealing on those sides.

Have you checked for vacuum leaks? Your symptoms would point that way.

Since the idle screw didn't work at the correct float level, I suspect the carb is dirty somewhere inside, has it been cleaned yet? If you stop slow and smooth, does it keep running? Sounds like a high float problem, does it smoke on restart? even a little black smoke is a indication of to much fuel.

Joe

I figured out my problem. My carb float bowl is not like other rochester bc carbs. Here is an image of what the bowl should look like.

http://bangshift.com/assets/galleries/3138/goliath_carb_35.JPG

Mine is the same except where the hole just to the right of the center, there is a small recession and a bronze or copper tube sticking out. That bronze tube mates with the top section. Anyway, on mine it needs an O-ring to seal it from gas in the bowl. On turns or braking hard, the gas would enter that tube/hole and kill the engine. I put one on and it seams to fix the problem 90%. The O-ring I put on it was the only one I had and it is a little too big, tomorrow I will put an appropriate size one. Today's test ride was much better than yesterdays.

The carb is a rebuilt unit from advance auto parts. About a year old. It runs great.

Ooooh, finding the trouble is great! Usually intermittent stuff is tricky to find.

Next I will change out the Oring and adjust the float to factory specs. Hopefully it will run right. Currently its at 1-14/32" and drop at 1-28/32". I hope this can help someone else in the future.

I just rebuilt my rochester carb and the kit came with a little o-ring I didn't need on my carb. I was looking at the blow-up diagram and it says: "O-ring - vacuum channel tube (partial-starting 1965 models)" I'm guessing you were getting gas sucked into the vacuum port causing an overly rich condition.