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Old 08-06-2018, 10:26 PM   #1
noyo55
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Default Model B Carb

I have decided to install a B carb on the B engine in my 30 Coupe. I dredged up a B intake, from all the stuff in the back of my shed. What am I looking for, part numbers for a Zenith and what aftermarket carbs were made for it? Thanks.
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Old 08-06-2018, 10:38 PM   #2
Terry, NJ
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Default Re: Model B Carb

I think it is wise decision! The "B" has it all over the "A" for at least three reasons. 1) The float is hinged sideway, not fore and aft as an "A" carb. Sudden stops don't make it stall.
2) The "B" carb has an accelerator jet tube that helps with acceleration.
3) The "B" carb has a much larger bore (1.250) and can process more air. If you go to my album "Miscellaneous stuff" I took some pics for a side by side comparison.
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Old 08-09-2018, 05:46 PM   #3
noyo55
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Default Re: Model B Carb

Thanks Terry I did look at the carbs. Good to see what I'm looking for. Tom
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Old 08-09-2018, 07:24 PM   #4
Gene F
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Default Re: Model B Carb

I went with it due to a bigger bore, and more air too.
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Old 08-09-2018, 10:34 PM   #5
lake_harley
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Default Re: Model B Carb

I'm a complete noobie to Model A's, but I thought that linkages line up better if a B carb is used with an A manifold. If I recall correctly, it has something to do with the flange on a B manifold being angled slightly that then puts the carb at an angle. To gain the performance benefit, I also understand that the A manifold needs to be bored to match the larger B carb. I also have a B carb to put on an A and would like to know if my understanding and/or information is correct, or all messed up.


Lynn
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Old 08-10-2018, 04:22 AM   #6
Tom Wesenberg
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Default Re: Model B Carb

Lynn, you are correct.
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Old 08-10-2018, 11:21 AM   #7
Terry, NJ
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Default Re: Model B Carb

Lynn, I've gone with the bored out A manifold (1.250 VS 1.125) and I have had no problems, No "Chinese" screws. In the shops, a "Chinese" screw or bolt was one where the shank was smaller than the thread size to accommodate misaligned hole. My linkage seems to work OK. If you want to bore out your manifold, you'll need a Bridgeport or a large heavy Drill press with a large angle plate, and a 4" LG locating pin approximately 1.100 dia. Write me for details.
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Originally Posted by lake_harley View Post
I'm a complete noobie to Model A's, but I thought that linkages line up better if a B carb is used with an A manifold. If I recall correctly, it has something to do with the flange on a B manifold being angled slightly that then puts the carb at an angle. To gain the performance benefit, I also understand that the A manifold needs to be bored to match the larger B carb. I also have a B carb to put on an A and would like to know if my understanding and/or information is correct, or all messed up.


Lynn
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Old 08-10-2018, 12:54 PM   #8
denniskliesen
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Default Re: Model B Carb

Most people bore an A manifold, I elected to weld up the flange on my B manifold and drill the holes the same angle as an A. My GAV works perfect as well the rest of the carb linkage.
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Old 08-10-2018, 02:25 PM   #9
Purdy Swoft
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Default Re: Model B Carb

I also cut the flange off the model B intake and brazed it back on at the model A angle . The model B intake is a better choice to get the full power of the B carb . Boring out or reaming out the model A manifold runner gives improvement but the runners that connect to the engine are also larger on the model B intake . The top of the model B intake is flat and had an effect on distribution of the mix to the intake valves. If the intake ports are enlarged on the model A block to model B size and used with the B intake manifold you should get nearly a three horsepower increase with the B carb . Another consideration is that two different inside diameter venturis were used with the model B style carburetors . The smaller venturi was used when the B carb was sold as a replacemnent for the model A carburetor after the model A Zenith carbs were discontinued . Both venturis are available but if you want the full effect you will need the larger model B venturi .
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Old 08-10-2018, 03:08 PM   #10
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Default Re: Model B Carb

I like Purdy's idea of cutting the flange off and brazing it back on. Much easier to do and I'll do that to the next B manifold. Thanks Purdy!
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Old 08-10-2018, 05:22 PM   #11
Purdy Swoft
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Default Re: Model B Carb

You are very welcome .
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Old 08-11-2018, 05:14 AM   #12
Dave Slater
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Default Re: Model B Carb

Purdue, would you know the Venturi ID measurements of the two "B" ones. I would like to know which one I have. Thanks Dave
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Old 08-11-2018, 11:51 AM   #13
ursus
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Default Re: Model B Carb

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Originally Posted by Dave Slater View Post
Purdue, would you know the Venturi ID measurements of the two "B" ones. I would like to know which one I have. Thanks Dave
22mm I.D. for the Model B and 20mm I.D. for the Model A replacement. They are otherwise interchangeable.
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Old 08-11-2018, 12:04 PM   #14
Charlie Stephens
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Default Re: Model B Carb

Sacramento Vintage Ford has (or will soon have) the bolts that allow the carburetor to be rotated under part number 5112. The part is not in their catalog, call them.

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Old 08-11-2018, 12:35 PM   #15
Purdy Swoft
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Default Re: Model B Carb

Dave , I'm having problems finding exact sizes of the two venturis that could be used with the model B carbs . If it has the same inside diameter as the model A venturi, it won't be the one that you want to use. Try Dave Renner at Renners corner , He should have the parts and dimensions PH 734-428-8424
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Old 08-11-2018, 02:34 PM   #16
Benson
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Default Re: Model B Carb

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Originally Posted by Purdy Swoft View Post
Dave , I'm having problems finding exact sizes of the two venturis that could be used with the model B carbs . If it has the same inside diameter as the model A venturi, it won't be the one that you want to use. Try Dave Renner at Renners corner , He should have the parts and dimensions PH 734-428-8424
Purdy,

The Zenith Model B carb for the Model B engine uses a 22 mm (.866 inches ID) Venturi.

The Model A version of the Model B carb uses a 20mm (0.787 inch) Venturi.
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Last edited by Benson; 08-11-2018 at 02:58 PM.
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Old 08-11-2018, 03:46 PM   #17
Charlie Stephens
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Default Re: Model B Carb

Just got a call From Dave Renner and he has those bolts that allow the carburetor to be aligned when using a B carb on an A manifold, rennerscorner.com, (734) 428-8424. His part number is B 9510-SS. He is a small supplier that specializes in Model B Ford parts in case anyone is into that kind of thing.

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Last edited by Charlie Stephens; 08-11-2018 at 05:58 PM.
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Old 08-11-2018, 04:42 PM   #18
Purdy Swoft
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Default Re: Model B Carb

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Originally Posted by Benson View Post
Purdy,

The Zenith Model B carb for the Model B engine uses a 22 mm (.866 inches ID) Venturi.

The Model A version of the Model B carb uses a 20mm (0.787 inch) Venturi.

Benson ,

Thanks for the info . Its hard to tell the size when buying B carbs at swap meets . I've got one of the model A replacement venturis for the model B style carbs that I sometimes use for comparison when working on model B carbs . Its good to know the exact sizes . Thanks again .
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Old 08-11-2018, 04:49 PM   #19
Purdy Swoft
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Default Re: Model B Carb

Thanks Ursus for the info . I misplaced my measurement info and have been using a used venturi for comparison. I will write this info down and try not to lose it again . Thanks , Purdy .
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Old 08-11-2018, 09:15 PM   #20
Benson
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Default Re: Model B Carb

Looks like I missed Urus' post 13 with same info I posted.

I was posting from the tiny screen of cell phone while over at the hospital (interruptions)
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Last edited by Benson; 08-11-2018 at 09:22 PM.
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