Ditched the "Air Maze"...

[RENNERS CORNER]

I have wonder if most people know that all of these carburetors Ford released for the model A & B were NOT designed for air cleaner use ?

It's NOT about opinions....

Zenith released this document in 1937 warning people about this, but people act like Zenith must be stupid and want us to ruin our engines.

I guarantee that people are not smarter today than they were back then.

It is 100% true that an air cleaner will make your engine last longer, but that's only if the carburetor internally was designed for it, if the carburetor is not designed for it, then the opposite happens. If air flow into the carburetor is restricted even a smallest amount then vacuum from the engine pulls air through the float bowl vent. This inrush of air pushes extra fuel through the jets. Then the raw fuel going through the engine washes oil off the cylinder walls, causing scoring and accelerated engine wear far worse than any dust would ever do in a lifetime.
You cannot compensate for this by adjusting the carburetor or changing the jetting.

The reason why people say that they put an air cleaner on there and they take it off and they don't notice any difference is because this is not something that happens overnight just like a dirty filter, it gets worse with time.
There is no warning or symptom that tells you this is happening. It's a slow death, but worse than dust would cause.

It's the design of the float bowl vent circuit that makes adding ANY potential restriction to the carburetor cause a problem.

All carburetors released for use on the model A have the float bowl externally vented. Every carburetor that has an air cleaner has the float bowl vent inside the carburetor near the choke plate so that all the air entering the carburetor must pass through the air cleaner.

When people talk about a pressure balancing circuit basically they're talking about relocating the float bowl vent from externally to internally.

It's a relatively simple job. If anybody is interested, I'd be glad to share the procedure for all Zenith, Marvel and Tillotson Ford released carburetors.

So here's where a little bit of speculation comes in.... so why didn't Ford put an air cleaner on this car?

I believe it's because you have a gravity supply fuel system, and a needle and seat fuel shut off assembly that can stick open with dirt and when this happens, you will fill any kind of air cleaner or contraption full of fuel, and when you do that combined with poorly adjusted spark advanced lever, you will create a fire that you cannot put out. People will say well Fire won't go through the screen on an air maze that might be true, but that does not prevent a backfire from blowing the whole canister right off the carburetor spreading the fire everywhere.

Ford knew all this that's why they didn't add the pressure balancing vent relocating circuit, why would they design a circuit into a carburetor that would never be needed. At the time Zenith had plenty of carburetors designed for air cleaner use. That wasn't the issue, they knew full well what air cleaners did and how to make them work on carburetors.
I believe that Ford's idea was to let accidental extra fuel just run on the ground where it would be no problem and that the fresh air coming through the radiator would pressurize the area under the hood, and the engine pans would funnel clean air into the carburetor.

In 1932 Ford released two items that attached to the carburetor. The first was called an air silencer, which was a noise baffle, it had a very course piece of screen on the bottom, which was unrestrictive. Then they had a firewall mounted oil bath air cleaner, which traps dust by passing it by a pan of oil, and these will not cause a restriction to the incoming air.

This is carburetor design 101 not opinion.