black spark plugs

Unknown

I pulled my spark plugs to check them on my 54 wasp 232 and they were black and sooty. They were also set at 16 thou gap. I increased the gap to 35 thou and reinstalled them. I started the car up and watched the carb as the car warmed up what I noticed is that there is a brass tube half way down the carb that spits gas periodically as the car is idling. When I move the throttle the brass tube then shoots lots of gas to rev the car up. I put a new carb kit in and set the float level to proper specs but the brass tube is still spitting gas. Is it supposed to? I noticed too that my exhaust pipe is as black as the spark plugs were so it has been running rich for quite a while. Any suggestions of what I can do to improve the situation?

Unknown

Yes, a black/sooty residue on plugs and in the exhaust indicate a rich condition. From what you describe, it sounds like your accelerator pump must be leaking at idle. Check the accelerator pump. If gas is spilling from the bowl vent, your float setting is too high.

Unknown

Dave, thanks for replying. What exactly am I looking for with the accelerator pump? Do I need to lower the pin?

Unknown

If your accelerator pump is leaking, it will need a new leather seal. It should only admit gas into the carb throat when you hit the gas pedal. It is possible that your linkage could be maladjusted. This is assuming that I'm understanding your explanation. To make sure we're on the same page, I'll be happy to check my carb manual if you'll give me your carb number.

Unknown

Jim, assuming the float level is correct, it does indeed sound like the accelerator pump is leaking; did the rebuild kit you got include a new one, or at least a new seal to put on the old piston? If so, did you put oil on it when you installed it?



The spark plugs being set at .016 were a great deal of the problem, as that close a gap will produce a weak spark insufficient to fully combust the mixture. This will create an artificially- over-rich condition at the exhaust. However this doesn't explain your leakage from the pump at idle. Make sure the pump linkage is adjusted so that the piston is not at all applied when the motor is idling.



I have seen the accelerator pump cylinder (that the pump piston rides in) significantly worn on a few carburetors, this required honing with a brake cylinder hone and installing a home-made sheet leather seal larger than the original. It really takes a lot of use to encounter this condition, however.

Unknown

ok thanks for the input guys. the carb is a WA1 Dave. I bought a rebuild kit and had a friend who rebuilds dozens of carbs a month professionally redo it for me but he had never done a wa1 before so wasn't sure of the settings. I'll recheck the float level and see about the accelerator pump.

Geoff

Jim, the Wa1 have ball check valves for the accelerator pump, and it may be that these have been left out. You cand check the operation by looking donw the carby throat, and opening the throttle, you should see a good squirt of fuel squirt out of the discharge nozzle. If not it is likely the check balls are displaced, or the leather cup is worn, but if the carb has been rebuilt this is unlikely. Then again, what you are seeing may be just a normal thing. It's not possible any more to diagnose fuel mixture by the clour of the exhaust or the plugs. Since unleaded gas has been the norm, all exhaust pipes are black. And until you have done a decent high speed run with the engine thoroughly warmed up the bottom of the plugs are likely to bit on the black side. If the check valves are missing there will be a definite flat spot on acceleration. You really need to judge the mixture on the performance on the road, and the fuel economy before you get too carried away.

Geoff.