Carter WCFB Troubleshooting
Thread Starter
Instructor
Joined: Jan 2002
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Carter WCFB Troubleshooting
Good Afternoon Vette People,
I am in the process of troubleshooting a Carter WCFB on my
327. The problem is 2 fold. The Idle is erratic (up and down). But the big problem is it intermittenly stumbles on acceleration. Or should I say it intermittently acellerates properly between stumbling... Just did the rebuild on this one. I'm hoping I can adjust this away. It was a little strange that the rebuild kit didn't address the throttle plate. The Throttle Plate does have a bit of play in linkages and butterfly rods. Any suggestions would be helpful...
Also can anyone tell me, Can an Edelbrock 1405 (AFB remake) carb bolt on to a WCFB compatable intake Manifold? My Manifold is a '57 chevy the WCFB bolts right onto it. THinking about changing over to a carb that is still in production for this one as it is a driver...
Thanks Take Care,
Shawn :chevy
[Modified by stouro, 2:38 PM 4/21/2004]
I am in the process of troubleshooting a Carter WCFB on my
327. The problem is 2 fold. The Idle is erratic (up and down). But the big problem is it intermittenly stumbles on acceleration. Or should I say it intermittently acellerates properly between stumbling... Just did the rebuild on this one. I'm hoping I can adjust this away. It was a little strange that the rebuild kit didn't address the throttle plate. The Throttle Plate does have a bit of play in linkages and butterfly rods. Any suggestions would be helpful...
Also can anyone tell me, Can an Edelbrock 1405 (AFB remake) carb bolt on to a WCFB compatable intake Manifold? My Manifold is a '57 chevy the WCFB bolts right onto it. THinking about changing over to a carb that is still in production for this one as it is a driver...
Thanks Take Care,
Shawn :chevy
[Modified by stouro, 2:38 PM 4/21/2004]
Race Director
Joined: May 2000
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Re: Carter WCFB Troubleshooting (stouro)
Did you check that all adjustments are with shop manual spec?
Notwithstanding the above, throttle shaft bore wear will cause differing idle speeds. If the throttle shaft has noticeable play it's time to send it out to a specialist who can rebush the throttle shaft.
Duke
Notwithstanding the above, throttle shaft bore wear will cause differing idle speeds. If the throttle shaft has noticeable play it's time to send it out to a specialist who can rebush the throttle shaft.
Duke
Drifting
Joined: Feb 1999
Posts: 1,808
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From: CA central coast
Re: Carter WCFB Troubleshooting (stouro)
Just a bit more info is needed: what were the symptoms BEFORE you rebuilt it? (ie, are these new symptoms or still the same old, same old?)
What year Vette and what version engine is this?
If you did the rebuild to get rid of those symptoms, it may not have been the carb, although the loose throttle plate linkages could be an issue.
Erratic idle could be a vacuum leak; vacuum leaks can be chased by running an unlit propane torch slowly around the intake manifold edges and along vacuum hoses... the engine will smooth out if the propane gas is sucked in (this method is not always foolproof, but can be helpful). Of course there are other possible causes like valve lash, worn valves, windshield wiper vacuum line, bad head gasket, etc.
Stumbling on acceleration (assuming the spark plugs aren't misfiring) is usually an accelerator pump or pump adjustment... you should see a strong stream of fuel immediately when you open the throttle while looking down into the carb; I think it could also be a bad distributor vacuum advance unit.
Hmmmm, both problems could be caused by a vacuum leak. Might be useful to measure engine vacuum at idle.
What year Vette and what version engine is this?
If you did the rebuild to get rid of those symptoms, it may not have been the carb, although the loose throttle plate linkages could be an issue.
Erratic idle could be a vacuum leak; vacuum leaks can be chased by running an unlit propane torch slowly around the intake manifold edges and along vacuum hoses... the engine will smooth out if the propane gas is sucked in (this method is not always foolproof, but can be helpful). Of course there are other possible causes like valve lash, worn valves, windshield wiper vacuum line, bad head gasket, etc.
Stumbling on acceleration (assuming the spark plugs aren't misfiring) is usually an accelerator pump or pump adjustment... you should see a strong stream of fuel immediately when you open the throttle while looking down into the carb; I think it could also be a bad distributor vacuum advance unit.
Hmmmm, both problems could be caused by a vacuum leak. Might be useful to measure engine vacuum at idle.
Melting Slicks
Joined: Oct 2001
Posts: 3,025
Likes: 12
From: Pleasant Grove AL
Re: Carter WCFB Troubleshooting (stouro)
Don't think the AFB will bolt on the WCFB manifold. I THINK the bores in the AFB are larger.
You can try loosening the screws on the throttle plates, tap the plates with a screwdriver until they are as tight as possible, and then retighten the screws. This adjustment is commonly overlooked on WCFB's and can cause a lot of leakeage.
If that doesn't help, the shaft bores probably need to be bushed.
As far as the stumble goes, that would seem a classic example of accelerator pump malfunction/misadjustment. :auto:
You can try loosening the screws on the throttle plates, tap the plates with a screwdriver until they are as tight as possible, and then retighten the screws. This adjustment is commonly overlooked on WCFB's and can cause a lot of leakeage.
If that doesn't help, the shaft bores probably need to be bushed.
As far as the stumble goes, that would seem a classic example of accelerator pump malfunction/misadjustment. :auto:
Thread Starter
Instructor
Joined: Jan 2002
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Re: Carter WCFB Troubleshooting (62fuelie)
Good Morning Vette People,
Thank you Duke, yes the over all throttle set up has considerable play and bushings and pressed fittings on the shafts probably need attention.
Wayne, the symthoms are the same old same old and yes I did the rebuild to correct these problems. It always did have an eratic idle.
But It didn't stumble under acceleration before. I've had this problem for about 3 weeks. As far as I could tell the settings are in accordance with the manuals. I even removed it a second time and rechecked the float adjustments and had to make some corrections. But that didn't work. The books I have keep refering to a Lean Mixture, BUT the carbon coming out of the exhaust and strong fumes make me think too rich? This particular engine is a 66 block with 67 heads and a 57 intake manifold. Other than some choke issues this carb performed pretty well for the last couple of years, although the idle never was really steady. I guess I will hook up the timing light and check out the vacuum advance operation. I don't know if this is really important, but the acceleration stumble occurs weather the engine has the load of the transmission being applied or not. I will also check the bolts on the throttle plates...thanks 62 fulie!
Again thanks for the Help..
Take Care,
Shawn :chevy
Thank you Duke, yes the over all throttle set up has considerable play and bushings and pressed fittings on the shafts probably need attention.
Wayne, the symthoms are the same old same old and yes I did the rebuild to correct these problems. It always did have an eratic idle.
But It didn't stumble under acceleration before. I've had this problem for about 3 weeks. As far as I could tell the settings are in accordance with the manuals. I even removed it a second time and rechecked the float adjustments and had to make some corrections. But that didn't work. The books I have keep refering to a Lean Mixture, BUT the carbon coming out of the exhaust and strong fumes make me think too rich? This particular engine is a 66 block with 67 heads and a 57 intake manifold. Other than some choke issues this carb performed pretty well for the last couple of years, although the idle never was really steady. I guess I will hook up the timing light and check out the vacuum advance operation. I don't know if this is really important, but the acceleration stumble occurs weather the engine has the load of the transmission being applied or not. I will also check the bolts on the throttle plates...thanks 62 fulie!
Again thanks for the Help..
Take Care,
Shawn :chevy
