56 WCFB Issues - A hole in my gradual acceleration

[Mark P.]

My 56 restoration project is almost complete and I am having an issue with my primary carburetor. It starts and idles great and revs fine when you pump the throttle. The problem is on gradual acceleration...it just acts like it is dying and has a huge pause in the accleration as you gradually ramp up the throttle. If you go quick, it jumps over it and seems fine. I originally thought the power valve spring was incorrect, then reworked the accelator pump. Those both appear to be fine, but I still have the problem. My car is ready to go except this last issue! metering rod issue? Power valve? Other adjustment?

Any suggestions?

Thanks, Mark

[Brooks G.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

Mark, I am also working on a 1956 with dual carbs. At times it seemed like having dual carbs was double trouble. In my case I was under the mistaken notion that the front carburetor was used only during full acceleration. Wrong! My car would drive OK till I came to a stop light or stop sign at which time it would want to die. I am not sure if it is correct or not but I have idle screws on both front and rear carburetors. In my case we ended up turning up the front carburetor and turned down the rear. That has worked so far for me. I wish you good luck! Brooks Glover Jr. (2141)

[Bryan H.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

have you cofirmed the dwell on the dist timing? also check vacuum on carbs during the acceleration. i have a early 56 and my issue sounded similar but was corrected by adjusting the dwell on the dual points. Bryan Hepper 42470

[Mark P.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

Will double check the dwell and timing, but when I disconnect the linkage on the primary carburetor, the motor trhrottles up gradually just fine. After adjusting the metering rods, re-adjusting the idle mixture screws and shifiting the accelerator pump to the lower hole (all recommended by Chuck Smith) I still have the problem of it cutting out as I gradually ramp up the accelerator. Since the secondary carb will throttle up and down without issue and the primary will not, it leads me to believe that it is carburetor related, not timing or dwell. Maybe a plugged passage? Will keep checking...

[Timothy B.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

Mark,

I don't know much about duel carburetors but is there a progressive linkage that could be adjusted wrong. Keep in mind that many carburetor related problems are actually ignition problems so make sure the dwell and timing is correct.

Sounds like the engine goes lean when the primary throttle blades open. This could be a vacuum leak somewhere, who overhauled the carburetors and are you sure the gaskets are correct?

[Mark P.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

Not ignition related...the secondary carb throttles up evenly and nicely when linkage is disconnected from the primary carb. i kind of figure that ignition and dwell problems will affect both carburetors and not be selective in the caruburetor that they will negatively impact. Pretty sure that the gaskets are correct and that the overhaul was done well. Am going to tear into it again and see if I have missed anything or if there are any blockages anwhere. Just blow it out really good and make sure it's all clean.

Any chance a non-tight (semi-stripped) carburetor screw or two near the middle of the carburetor coud be the culprit? Some of the threads are getting a little weak after all these years so I don't dare tighten them too much anymore. Maybe I'm not getting a good enough seal around the perimeter and the interior of the carb compartments.... A factor?

[Bryan H.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

you can put a threaded fitting on the back carb and check the vacuum on it. there are readings at certain rpm's that should confirm it isnt leaking. paragon carries them.. look on the carb to see if you have a bolt inserted into the fornt..distributor may be in the way...so you accelerate without the 1carb and it doesnt break up? this would indicate eithher linkage or a leak then??

[Mark P.]

Re: 56 WCFB Issues - A hole in my gradual acceleration

As an update, after checking everything out from top to bottom, a previous owner (the carburetors had never been run since I have owned them) apparently swapped out the metering rods for a larger diameter. No wonder they weren't working correctly and I had no gradual acceleration! Anyway, traded them out and the car now runs great. Thanks to everyone for your advice...even thought it was something entirely different.

Mark