A carb runs good but B carb doesn't

1

1929tudor

Senior Member
I bought a B carb a couple years ago (actually forgot I had it) and put it on my 31 roadster today after a good cleaning and it runs good idling but when I give it gas fast it sputters and spits. I put my A carb back on and it runs fine. What would cause it to do that? Would like to use the B one if I can get it running better. If not then I'll sell it and go back to the old standby. Thanks
 
The B-carb has many small and convoluted passages that are bound to be occluded after all these years and a bear to clean out well. Incomplete or erroneous diagrams and instructions abound--I would start with a search of Charlie Yapp's Secrets of Speed magazine. I fiddled with myself and tried two professional rebuilders on the two B-carbs I bought before finally giving up and going back to a Zenith-1 that ran pretty well. Recently switched to the more modern Zenith 13922.

Your results may vary. Some folks have had good luck with them. They usually conclude that the rest of us are just incompetent, which I will happily grant IF they likewise agree that others may be just lucky.

Steve
 
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1929tudor said:
I bought a B carb a couple years ago (actually forgot I had it) and put it on my 31 roadster today after a good cleaning and it runs good idling but when I give it gas fast it sputters and spits. I put my A carb back on and it runs fine. What would cause it to do that? Would like to use the B one if I can get it running better. If not then I'll sell it and go back to the old standby. Thanks
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Try opening the GAV about a half turn or more and see if that helps, if it does, then run it that way untill it warms up. after the engine warms up close the GAV all the way, this is the way you should run the B carb after warm up. If it still sputters after warm up, you have a partial blockage and more cleaning will be needed. Maybe you will need to remove the passage plugs and run a wire or small 1/16 welding rod through the passages. Good luck.
 
forever4 said:
My experience is just the opposite. What convoluted passages? Much easier than an 'A' to remove plugs without drilling and to properly clean out.

The source of a lot of the confusion and discussion about erroneous drawings is SOSS and J.J. The Ford Service Bulletins drawings is correct, just misunderstood because some of the named jets on a Model A look nothing at all like the same named jets on a Model B.

I have a number of pages on my web site with original Ford and Zenith drawings and specifications for the A and B carbs.

I have rebuilt many of both carbs successfully, including about 35 A carbs and 5 B carbs this summer. I am also the source for the power jet tube, which is not reproduced or available anywhere else.

Short story:
They are both good carbs when properly cleaned and rebuilt, and I believe the B is superior.
Patience and attention to detail is all anyone needs to work on them.
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Only repeating what I recall hearing and reading over the years. Glad to learn I was wrong. Guess I picked the wrong rebuilders.

If anyone's interested in the SOSS archives, a full index is available online:

http://www.secretsofspeed.com/MAG-INDEX.htm

I see stuff listed for volumes, 3, 6, 10, 13, 14.

Steve
 
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