Model B Carburetor

[JimK1930A]

I know some people use air filters on their Zenith 1, 2 or Tillotson carburetors, but am wondering if there are any opinions about using an air filter on a model B carburetor?
I am interested to hear from those that have converted from using a Zenith 1, 2 or Tillotson carburetor to a Model B carburetor.
I would especially like hearing about your experiences good and bad.
Thank you,
Jim Kelly
Minneapolis, MN

[pat in Santa Cruz]

I made up a filter horn using a piece of 2 inch copper street 90, shortening the flare end by 1/2 inch and soldering the cut off piece inside to bush it to fit the carburetor. Then I adapted the filter element flanges from an A airmaze to the horn and to accept the longer filter element. Since then I have seen the aluminum Airmaze horns meant for A's used by routing out the inside with a carbide bit until it fits the carburetor . That's cheaper, less time consuming and easier than modifying a copper 90. I use the 5 or 6 inch K&N filter, which number I cannot remember. I found it in their catalog.

There were filters available for B engines back in the day that were filled with oil soaked steel mesh/ heavy steel wool. In both cases of an A or B zenith, using the filter with the least restriction as possible is best, as neither carburetor has an ambient air tube to the fuel chamber from the intake side of the butterfly to equalize the air pressure. Using a more restrictive filter, such as paper or small surface area will result in a richer running engine. My experience with the low restriction elements is good as far as engine performance goes. The smaller paper elements made the engine too rich. Both the larger and smaller paper elements can get pretty clogged up if the carburetor leaks and soaks the element. In the case of the K&N or oiled steel mesh, any leakage just washes out the oil.

I only use the elements during dry weather anyway. The engine still seems to run better without any element, but that could be attributable to the moisture in the air or the cold air in winter and not the lack of a filter. Its all subjective on my part anyway. I haven't seen a definitive tests, like dyno tests to verify any of this. Opinions on filters will generate as much difference of opinion as what oil to use, Float O Motors, or whether or not to use marvel mystery oil.

[Manuel]

My car [a RHD 4 cyl B] came with an air filter [factory] which was missing all its internals.
Would any owners from RHD countries have one of these?
Would love to see a complete one or a pic.

Thanks,

Manuel in Oz

[Charlie Stephens]

Originally Posted by Manuel

My car [a RHD 4 cyl B] came with an air filter [factory] which was missing all its internals.
Would any owners from RHD countries have one of these?
Would love to see a complete one or a pic.

Thanks,

Manuel in Oz

If it doesnt look like the one on Vince's site it is probably the heavy duty oil bath filter. Can you post a picture? Do you have a copy of "The 1932 Ford Book" from the early Ford V8 club? (earlyfordv8.org)

Charlie Stephens

[Manuel]

Originally Posted by Charlie Stephens

If it doesnt look like the one on Vince's site it is probably the heavy duty oil bath filter. Can you post a picture? Do you have a copy of "The 1932 Ford Book" from the early Ford V8 club? (earlyfordv8.org)

Charlie Stephens

It is not the oil bath type. They were the same as the V8's but had different mounts and brackets etc to suit the 4 cyl motor.
This is completely different and like I said it is missing its internals [probably had some sort of mesh in there I guess].
Now it is stashed away with all my other "essential" spare parts :-)
Can't afford the 32 Book. Love to have one but it costs a fair bit by the time it gets here! [does it have pics of air filters??]
Cheers,
Manuel in Oz

[pat in Santa Cruz]

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as is often the case, photos and info on B carburetors can be found on Vince's website here:

http://www.fordgarage.com/pages/bairintake.htm

[Slantwindshield]

How many of us REALLY drive our Model A's down a dusty gravel/dirt road where we need an air filter????? Not many of us around here do. Howard

[Karl]

Originally Posted by Slantwindshield

How many of us REALLY drive our Model A's down a dusty gravel/dirt road where we need an air filter????? Not many of us around here do. Howard

I do - I did 160 miles on a rally on the weekend Probably 30 percent of it was gravel roads. Fortunately it was raining the whole time so the problem was not dust but mud ! Last year I took the coupe and the whole engine bay was covered in dust at the end of the run. Karl

[Manuel]

Originally Posted by pat in Santa Cruz

as is often the case, photos and info on B carburetors can be found on Vince's website here:

http://www.fordgarage.com/pages/bairintake.htm

Mine looks nothing like that Pat. Probably because the car is RHD.

Manuel in Oz

[Ian in Mississauga]

Manuel, are you sure you don't have a "silencer"?

[Manuel]

What is that?

[steve s]

Don't know how big a part it might be of your problem but neither the A or B carbs were designed for air filters; there is no provision for balancing the atmospheric air pressure in the float chamber with the slightly lower air pressure between the air filter and the jet outlets. Air filters necessarily make such carbs run richer. Whether or not it's a problem depends on how everything else is set up.

Here's a picture of the balancing mod made to my B carb. It was the last straw I grasped at before giving up on ever getting it to run right. Just one man's story.



Steve

[Ian in Mississauga]

Manuel, I bought a Zenith B carb a few years ago and it came with what looked like a filter except it was open at the bottom. I thought part was missing and I donated it to an auction. Someone said it was a silencer and did nothing except muffle the sucking sound. I hope yours is more useful.

[Manuel]

Originally Posted by Ian in Mississauga

Manuel, I bought a Zenith B carb a few years ago and it came with what looked like a filter except it was open at the bottom. I thought part was missing and I donated it to an auction. Someone said it was a silencer and did nothing except muffle the sucking sound. I hope yours is more useful.

Hi Ian,
It is not a silencer. From memory it sits at about the same height as the head with a long tube going down to the carby.
That way it clears the steering box.
All cars are RHD here.

Manuel in Oz

[Bruce Lancaster]

The standard USA filter was called a silencer in the book...it had double walls, like most later Ford filters, as the silencing part. The opening was covered by a couple of circular pieces of mesh sandwiching in a little cloth filter...this version was standard on passenger, commercial, and truck B's. A simple snap ring held the elements in place.
There were two optional heavy duty filters, both big oil bath rigs much like the ones used on many older industrial engines and '50's jeeps. Both mounted high, with a tube down to the carb...the earlier version bolted to the firewall, the later was bracketed to the head.

[Ian in Mississauga]

Originally Posted by Bruce Lancaster

The standard USA filter was called a silencer in the book...it had double walls, like most later Ford filters, as the silencing part. The opening was covered by a couple of circular pieces of mesh sandwiching in a little cloth filter...this version was standard on passenger, commercial, and truck B's. A simple snap ring held the elements in place.
There were two optional heavy duty filters, both big oil bath rigs much like the ones used on many older industrial engines and '50's jeeps. Both mounted high, with a tube down to the carb...the earlier version bolted to the firewall, the later was bracketed to the head.

Bruce, thanks for the info. That makes more sense than what I was told originally.

[vtwinsideways]

Jim, I am currently running a "filter" from a '40- '50's era Jeep on the B carb on my A p/u. Seems to work OK, but it requires cleaning and re-oiling on a regular basis. I had to reduce the neck slightly to fit it to the B. It fits quite nicely with a good gap between it and the exhaust. It has screen material in the bottom and some type of flame resistant mesh inside. I assume it is some form of asbestos fiber. It does restrict the airflow, so some carb adjusting is necessary when going from filtered operation to unfiltered. I haven't noticed any reduction in top end, but she is a little less snappy. I acquired a good oil bath to replace it, but have yet to find or fabricate the "snorkel" for it. Luke McLeod

[Bruce Lancaster]

Well, the B carb was always supplied with an air cleaner from the factory!
On design, there is a need for low restriction in an uncompensated carb. The big problem in the Ford four cylinder world is that most attempts at adding an air cleaner involve TINY filter elements, partially for easy mounting and partially an attempt to maintain a resemblace to the wretchedly undersized air maze. If you add a filter...get a good OEM remote can type, common on 1980's cars, with good quality paper element. All remotely recent filters are designed with lots of extra area so they can run for long periods without restricting flow. (an edit...if an aircleaner has any effect on your mixture, it is simply of inadequate capacity for your engine and needs to be bigger or to have a better quality element. Big paper filters are essentially non-restrictive until they accumulate a LOT of dirt.)
I think the newest car I have had without internal balancing vent was a '68 Chevy six. This type of vent was killed off about the next year by smog related redesign.
Worked fine unless maintenance got REALLY sloppy...if a sleazed off for about 2 years, the air cleaner would announce that it was full by a sudden drop from 20 MPG to wheezing around in a cloud of black smoke.
I think all Fords from 1932 up had filters, all silenced except for some truck variants, and first internal venting was on some later, roughly 1942-up, Ford 94 carbs. This development seems to have been for an entirely different mixture reason...the high mounted flathead fans tended to pressurize the float bowls through external vents!

[steve s]

Originally Posted by Bruce Lancaster

Well, the B carb was always supplied with an air cleaner from the factory! ...

Bruce,

According to my reading of the Ford Service Bulletins, the air cleaner was introduced in July 32 for trucks as a service item available from dealers for operation "where the dust conditions are most severe". Instructions are also included for significant trimming of the engine pan necessary so cleaner will fit. The Sept-Oct 32 bulletin mentions "available through service for installation on the improved 4-cylinder chassis", which I assume means the cars. In March '33, a redesign of the cleaner is announced that permits mounting to engine cylinder head studs, rather than firewall. The Feb '35 bulletin mentions use "where the dirt and dusty conditions are too severe for the ordinary screen type silencer." That same bulletin also has a digression on the relative hazards of different types of airborn dust. Also, they give best oil levels for operation above 3500 rpm (70 mph!) and below 1000 rpm. Really doesn't sound like they quite all came from the factory with the oil bath air cleaner, but rather the screen silencer, as described in Vince's website linked by Jason above.

I guess they must have worked ok, but I still think the carb wasn't really designed for them. My understanding is that somewhere in the mid-30's, Zenith started compensating its carbs.

Steve

[Jason in TX]

Here is a link to the heavy duty oil bath everyone is talking about.

http://www.fordgarage.com/pages/3233...aircleaner.htm

Pearsons in NZ sells Right Hand Drive gear. Their Website: http://www.pearsons.co.nz/

And a link to the current air filter they sell.
http://www.pearsons.co.nz/PDF%20and%...2017-02-10.pdf