WCFB Question
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,102
Likes: 171
From: Colorado Springs, CO
WCFB Question
After checking everything out, thanks to the responses from this forum, I am still experiencing high-rpm "lag" or cutting out on my 57 with the 2x4 wcfb setup (on a 350 crate engine). One thing I failed to mention, and it may not matter, is that the carbs are not matching. The rear carb has the large counterweights on the secondaries, while the front carb has smaller weights. Could this have an affect on performance at high rpm? I do have vacuum advance hooked to the base of the rear carb, and a pcv valve connected from valve cover to the base of the front carb. Any more thoughts/advice would be greatly appreciated! Thanks, John
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
vettepoor, your problem sounds like a lean condition that may be caused by secondary jets that are too small. Check with the ST-12 Shop Manual and see if the jetting and metering rods are correct. The counterweights are on the shaft of the air valves above the throttles in the carbs. Their job is to keep the secondaries from opening up until there is sufficient vacuum to pull the air valves open. There should also be a mechanical linkage lock-out on the passenger side of the carbs that would keep the secondary throttles from coming open until you floored the throttle.
The WCFB is the pre-curser to the AFB. The AFB has the same type of air valve above the secondary throttle blades, but the counterweights are hidden inside the lower housing of the carb.
If you need new jets and metering rods, they can be had from Danchuk or any of the carb rebuilders on this Board. Good luck.
The WCFB is the pre-curser to the AFB. The AFB has the same type of air valve above the secondary throttle blades, but the counterweights are hidden inside the lower housing of the carb.
If you need new jets and metering rods, they can be had from Danchuk or any of the carb rebuilders on this Board. Good luck.
Thread Starter
Burning Brakes
Joined: Mar 2006
Posts: 1,102
Likes: 171
From: Colorado Springs, CO
Problem Solved!
Thanks, Coves4Me! After reading your post, I pulled apart the front carb, and discovered that the secondary jets were 2 different sizes!
Tried increasing jet size, and car now seems to pull just fine in higher rpms. Now I just need to "fine tune" everything to get it just right. Thanks again for your help. 
John
Tried increasing jet size, and car now seems to pull just fine in higher rpms. Now I just need to "fine tune" everything to get it just right. Thanks again for your help. John
