I have a 1962 235 motor with Rochester 1 bbl. I rebuilt the carb a few weeks ago and problems ever since. There was an issue with no spark for some reason, I think i have that figured out. Now it is backfiring through exhaust, and won't idle at low rpms, just stalls. I also have to keep choke on a little bit so it will not stall. I rebuilt the carb a few weeks ago and problems ever since. There was an issue with no spark for some reason, I think i have that figured out. I reset the timing (i think it is right?) I set it too 1 mark clockwise past the circle but it was at higher rpms with the vacuum line disconnected. I should set it at low rpms? But how do i do that if it will not run at low rpms? I checked the float level twice on the carb and it is right on but seems like it is getting too much gas, and the gas/air mixture screw does not seem to be doing much of anything when I turn it. So far I have checked/switched to other used: points rotor cap spark plugs spark plug wires fuel filter coil I don't know if it is a carb problem or spark problem? or combination of both? Been working on it last 5 days and getting nowhere.
Why did you overhaul the carb? Was there an issue you were trying to remedy, or was it preventative? Some of the vintage cabs have base gaskets with cutouts for vacuum passages, did you get yours lined up?
The fuel filter is brand new, and did not make a difference. I rebuild the carb cause it would idle erratically sometimes, then it would be fine the next time i started it. So i assumed there was something wrong with the carb. When I took it apart i noticed one little tiny shiny spot on the float where it was rubbing the gasket at a certain level. All the passage ways are clear. It is possible for the fuel pump to pump TOO MUCH gas in the carb if the fuel pump got messed up for some reason?
I found I had 2 small hairline cracks in the spacer between the carb. and intake once, that was giving me some issues and making performance erratic at different RPMs. Posted from the TJJ App for iPhone & iPad
I had the same problem the old base gasket was crack so I replace the spacer gasket there is is a vacum orfice that looks like it should line up. wrong flip it over so the flat side of the spacer is against the bottom of your carb. That orfice is for a vacum operated choke sounds like you have a manaul choke.
If it worked ok before the carb work then go back to the carb. Sounds like a vacuum leak. I use a hand held propane torch with a hose on the tip to find vacuum leaks, just put some propane (not lit!) gas around the carb base with the engine running and see if the idle changes.
I THINK I found the problem! There does not seem to be any mechanical advance at all! I finally got it running excellent tonight at really low rpm and checked the timing it was right on. Then I reved it up and it was backfiring like crazy and had to keep feathering the throttle to get it to a higher rpm while my dad was still looking at the timing marks with the light gun and the timing did not move at all. So I am going to change distributes in a couple of days, will let you know how it turned out, thanks for everyones help. I actually made machined a thick carb gasket (same dimensions as original) a long time ago out of aluminum because the orginal one I dropped and it broke in 1/2! I picked it up and thought "what the heck kind of material is this made of??" My aluminum one has a thin cardboard material gasket on the bottom and one on top to seal everything nicely.
Hope that fixes your problem, keep us posted. I'm still wondering about your carb spacer though, the original was made out of Bakelite and was there as a heat insulator between the manifold and the carb. Also, the spacer, and spacer gasket, has some notches, that must line up with the carb's vacuum port. The notches go against the carb, not the manifold, and they can be put on backwards so care needs to be taken. If the vacuum port is blocked, the engine will run rich because the power piston thinks you're at WOT all the time. If you need the spacer and gasket they are available, I got mine from Chev's of the 40's but other vendors have them as well.
Ya it was the mechanical advance on the distributor. for some reason it would not open properly. I put a different one in (also old one had a slight wobble in it from bearing slowly wearing out) and now it runs top notch again. I never even thought to check that, but that is all that was left!