Hot Rods Carter WCFB troubles

We have run into a problem with a carter wcfb that we just rebuilt. It goes on a dual quad setup on a Chevy 301 with 202 heads. That back wcfb works fine but whenever we put fuel to the front one that we rebuilt the car will start and uncontrollably increase in rpm until we quickly turn off the key. It seems that the carburetor is leaking somewhere. The floats have been double checked and the idle screw is backed out all the way. The throttle blades are also complete shut. Any ideas?

Thanks,
TR

 

I should add that the 2 high speed idle screws are also all the way in…

 

Check fuel psi.
I believe 4 psi. Is when it stopped for me, With two Carter's on 6-71
Also running a mechanical pump..

 

its obviously getting fuel to keep upping the rev's. I always thought the 2x4 setup's had to idle and run with both carbs performing like one-meaning idle on both. Maybe drop the pressure to 3, open up the screws 1 1/2 turns, (assuming float level is correct), and be sure you don't have any vacuum leaks. Or, you could block off the rear carb and keep working on the front until it runs o.k.

 

Sounds like an air leak also to increase rpm. Fuel only would load it up and air only will lean it out to misfire. Dual quad SBC’s idled on both an were progressive and only the rear had the choke if original.

It doesn’t sound like the front ones butterflies are closed. The front one should have the front barrels just slightly cracked open.

I have swapped the carbs on mine and found which way works best since both have chokes. I’ve adjust the front one so it doesn’t come on.

They should be set with a unisyn after you get them close and idling on both.

 

Dual quads run best ( IME) running 1:1 linkage , both carbs idle .

 

You might find some useful tech information here . . .

https://www.jalopyjournal.com/forum/threads/carter-wcfb-tech.851851/

. . . Courtesy of @carbking. What a guy!

 

Try disconnecting the throttle linkage connecting the two carburetors.

Also, which WCFB's are you using, and which manifold?

If not O.E. Chevrolet, have you checked the flange gasket(s) sealing to both the carburetor flanges and the intake manifold?

Fast idle linkage on the front carburetor?

Jon

 

The butterflies on the carburetors are shut, the fuel pump is regulated to 4 psi. The gasket seals hood and the linkage is off of the carburetor now. We held the carburetor linkage shut with a spring but still no dice. The carburetor in question is shown in the pictures below. The tag is gone from the carburetor so I’m not sure exactly what model it is. The intake is a stock 1957 Chevy dual quad.


Thanks,
TR