Another C1 2X4 problem?

[Dave Christensen]

The front carb on my 56 2X4 drips fuel (a lot!) from the primary venturi while it is idling. I have set the floats, and rechecked the floats. I have pressure tested it for leaks. I had a carb shop pressure test it and check the floats. No problems found.

Except it still drips fuel. What could be wrong?

thanks
Dave Christensen

[Ed Jennings]

Re: Another C1 2X4 problem?

Have you tested the fuel pump pressure? WCFB's typically don't like more than 4 to 4-1/2 psi.

[Dave Christensen]

Re: Another C1 2X4 problem?

I have not tested the fuel pump pressure.

Will most parts stores have a gauge for doing this? The other carb is fine.

I have a stock passenger car pump (not the correct 2X4 long screw pump).

If the pressure is too high, what can be done about it?

thanks
Dave Christensen

[James F.]

Re: Another C1 2X4 problem?

Dave,
Most vacuum gauges have a pressure side on the scale enough to indicate fuel pump pressure. My 4262 pump indicates about 3.9 lbs pressure. Slightly low but OK. Unless your Corvette is produced after July the correct pump for your '56 is the 4262 and not the "long bolt" pump (which requires a 3/8" fuel line). Pump pressure can be lowered by drilling a small hole (max 1/8") in the pressure side valve. I've never done this, sounds like a way for me to destroy an otherwise good pump! As you said the rear carb is fine, I don't think fuel pressure is your problem. Sounds like one or more of the vent passages in your front carb is/are plugged. Both discharge passages to the venturi have anti-percolator vents. If air pressure can't get out then fuel is pushed out wherevere it can. Or fuel is leaking around the float needle valve. Regards, Jim

[Clem Z.]

Re: Another C1 2X4 problem?

i have seen leaks between the needle seat and where it screws into the carb body. you need to pressure check this with the carb top off and upside down.

[Dave Christensen]

Re: Another C1 2X4 problem?

Clem,
I did have a problem with a leak around the seat gasket. I finally got that fixed several weeks ago. I did take the top off and pressurize it with air underwater to find that. I am sealed up tight, at least in that area, now.

Do you have any other suggestions?

thanks
Dave Christensen

[Clem Z.]

Re: Another C1 2X4 problem?

drop the float level 1/8" and see if this make any difference. if it does try 1/16" and see what happens.

[Dave Christensen]

Re: Another C1 2X4 problem? fixed - thanks!

Thanks for everyone's help. I spent this afternoon with Chuck Smith and he went through the carbs for me and they now work great!

About the only thing that was right on the carbs were the castings. Chuck put in the correct jets, metering rods, and throttle plates. I can see that without a large parts supply, to go along with the knowledge of the carbs, there is no way to get them working properly if they are messed up.

thanks again

Dave Christensen