The Stovebolt Site Forums The Shop Area Engine Shop Carb?

OK, I've already purchased the rebuild kit for the "B" carb on the '56 engine in my '53. I'm thinking that my problem is the accelerator pump.
When accelerating, if I just open it up about half throttle, it stumbles, until I open it up to WOT then it doesn't.
What do you think?
The same or more?

If it is a carburation issue two things come to mind:

A passage in the accelatrator circuit could be restricted or blocked; I delt with this last summer with a Carter. Less likely would be the power valve.

I am not to quick to rebuild a faulty or suspected faulty carb. My approach is to learn how the particular model works. Then you can Isolate the problem to a particular circuit in a carb.

The accelerator circuit is easy to test. With the engine off and better if cool , operate the foot feed and you should see gas squirting into the carb.

John B

A bad acc pump will produce a big hesitation and maybe a backfire when you try and open the throttle. As mentioned you can test it with the engine stopped.

So, what would be the next step to finding the right problem?
I'm going to rebuild anyway you look at it, just need to see if something needs extra attention.

Sure won't hurt to clean it out, if thats not the problem, then no harm done and you can look else were. Check for vacuum leaks and check the timing. It never hurts to give them a complete tune up and looking over. Never assume anything new is still working as it should.

Joe

If you hold a steady part-throttle position, does the stumble continue? If so, the accelsrator pump is not the problem. It only works to smooth out the transition from idle to part-throttle, etc. by squirting a little gas to prevent a lean condition while accelerating. It sounds like your carb has a lean condition at part-throttle, maybe an incorrect jet or metering rod, or a partially-plugged fuel passageway. Full throttle opens up more fuel passages or gets beyond the lean spot, solving the part-throttle stumble.
Jerry

If it does not squrit gas, the acc pump is worn out or a passage is blocked. At this point, I would consider and possibly replace the accelerator pump with the carb in place. Doing so may not fix the problem (pluged passage). Then you will have to remove the carb and get out the pipe cleaners and compressed air source. If you attempt to work on a carb in place, there is always the danger of dropping somthing down the carb or a small part to the ground. Now you have a bigger problem. If you have a kit, you have what you need to do the job. It is possible to cut new gaskets for the top of a Rodchester.

I am not a believer in installing a full kit for any carburation problem. Learn the carburator, use what you need. If it aint broke don't fix it. I wished I learned that one years ago.