Carter Carb with off idle stumble

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Nov 17, 2003 | 06:31 PM

carp1

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Carter Carb with off idle stumble

Hello

I have a 400 and I just put a carter carb on it and now I have a bad stumble from 1000 to 1400. I think it is about were it transfers from idle to the primary circuit. Any guesses on how to fix this? It idles good and runs down the road good just taking off slowly it stumbles bad. In drive and brake on at 1000 to 1400 it runs rough and surges.

Thanks
Chad

Nov 17, 2003 | 07:34 PM

danlee

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From: Delaware

What size carb is it?

Nov 17, 2003 | 07:44 PM

carp1

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The carb is a 625 cfm. I had the carb on the truck when I had it rebuilt about 50,000 mile ago. I had a shutter in the engine then so I put a holley on it then found out that I had an internal vaccum leak "manifold would not seal" Got that fix so I decided to put the Carter back on. Then is started to stutter. I just put it back on this morning.

Thanks
Chad

Nov 17, 2003 | 08:01 PM

danlee

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From: Delaware

It sounds like a 'lean' mixture. Are you sure that vacuum leak is fixed?

You could try to change the metering rods to give a richer mixture in 'cruise'.

How about your accelerator pump and float level? If your float level is too low, then there is no fuel in the accelerator pump at light throttle.

Nov 17, 2003 | 08:18 PM

carp1

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Everything is set to the specs. I think you can rule out the accel pump because it you torque up the engine with the brake on it surges and stumbles I dont think the accel pump has an affect on it holding at one constant speed. Right now the carb is still jetted stock. It seems like it is having trouble going from the idle circuit to the primary circuit. Once you pass that point it runs great. Free reving at that rpm does do it a little but not like under a load.

Thanks
Chad