Ditched the "Air Maze"...

[Trapdoor2]

During my recent head gasket investigation, I noted that the spark plugs were seriously carboned up. Black black black. The engine wasn't running properly...like it was running rich (smelled like it too).

I still think the (Tillotson) carb is a problem...but I'm going thru all the easy things on the checklist (and I still need to finish refurb on the Marvel Schebler).

After sorting out the head gasket issues, I decided to pull the Air Maze and clean it. With it off, I took her for a drive...big difference in how she ran! Not stumbling, smooth idle at 480, no smell of raw gas from the exhaust.

Hmmmm...

Not an easy decision, I've never run an engine without an air cleaner. Yah, I know, I know. The car and carb were never designed to run with an air cleaner (not that the Air Maze does any "cleaning")...but I'm going to run without it. She certainly seems happier...now I have to see if I can straighten out the dent in the carb throat left by the screw that holds the Air Maze on.

I swapped out the plugs (from Autolite to Champion, gapped at 0.035") and I'll drive them for a while before rechecking.

[Ayers1]

I pulled the maze off mine for the same reason. Never could get it to run or idle properly.

[Big hammer]

Two thumbs up !!

[ronn]

I pull them all off. junk.............

[nkaminar]

The problem is not the filter but the design of the carburetor. The float bowl is open to the atmosphere. The fuel flow is determined by the difference in pressure between the jet and the float bowl. When a filter is installed the pressure in the venturi decreases causing more fuel to flow.

The carburetors can be modified by running a passage between the inlet to the carburetor, just before the choke, to the float bowl, and blocking off the opening to atmosphere. That way the pressure inside the float bowl is the pressure at the inlet to the carburetor. There have been a couple schemes on how to do this published here on the Barn.

[Synchro909]

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I agree with nkamoinar on this one. air balancing the carburettor would have fixed the issues some of you have had.

[old ugly]

i do believe in something to prevent crap from going into the engine via the intake, i use a wire screen air maze that stops the big chunks, it runs fine.

on the other side of the coin, i ran my model b (99% of pavement) for 40 years with no air cleaner and never had an issue.

if i was driving all the time down gravel roads i would for sure put a proper air cleaner on.

i guess it depends on the conditions you use the car in.

[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.

[German guy]

I soaked my 'air maze' in acetone...blowing it out and soaking several times again for a few days before trying it out again. I saw a major improvement! Decades of built up oily residue and crud came out. It still seems to be too restrictive of intake airflow but high quality after-market options simply look far too modern.

[Bob Bidonde]

For over 50 years I have run Zenith carburetors without any filter or air maze gizmo. I have not yet had any chunks of debris or notice accumulation of crud in my carburetors. Here is another shocker. The Zenith carburetors on both of my Model A's have not been taken apart or had any adjustment for many many many years. I do not use any additives in the 87 Octane 10% Ethanol gasoline I run. Most every engine stoppage I have experienced was due to ignition failures (coils, points, condensers, plastic body parts). I think the carburetor is the most maligned & falsely accused part on the Model A.

[cadillac512]

"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."


Yes, please do share. Thanks for your insight.

[Canton_Model_A's]

Mine had one, and took me all of 5 minutes to rip it off and find the trash can.

[Trapdoor2]

Originally Posted by German guy

I soaked my 'air maze' in acetone...blowing it out and soaking several times again for a few days before trying it out again. I saw a major improvement! Decades of built up oily residue and crud came out. It still seems to be too restrictive of intake airflow but high quality after-market options simply look far too modern.

I wasn't surprised to find that my Air Maze was filthy...on the side facing the engine. On the viewable side, it looked clean. I'll clean it up and put it in my "possibles" box with the other one. Maybe one day I'll get to a swap meet and trade them for something...

[gz]

Engine pans keep the crude from going into the carburetor. Engine pans also are used for cooling. Most all cars had them since cars were first built.
They were often thrown out because they were a pain in a$$ to reinstall them or they rusted out, but they were there for two reasons.

[David R.]

I agree with Bob Bidonde, the Zenith model A carburetor is nearly bulletproof if it is properly set up and fed a constant clean diet.
If a person takes the time to understand how it is designed to utilizes atmospheric pressure and air velocities to regulate fuel mixtures over various operating conditions it will be evident why you don’t want an air cleaner unless you air balance the bowl. The Zenith is quite a fascinating piece of work, like just about everything else on the car, simple and effective. I suspect more to blame for carburetor issues should be dirty rusty fuel tanks. People don’t want to go to the trouble to remove tank and properly clean and seal them.

[Hitman]

Originally Posted by 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 ?

Ford never released air filters for the A or B carburetors, but they did offer intake silencers for the B engine. They were mostly to silence the intake, but they did have a mesh screen that functioned as a filter similar to the airmaze, but not a filter that we know today.

They did also offer a filter for BB trucks in dusty conditions, using the oil bath style.

Air filters are quickly becoming the "what's the best oil to use" topic of the 2020's!

[RENNERS CORNER]

Originally Posted by Hitman

Ford never released air filters for the A or B carburetors, but they did offer intake silencers for the B engine. They were mostly to silence the intake, but they did have a mesh screen that functioned as a filter similar to the airmaze, but not a filter that we know today.

They did also offer a filter for BB trucks in dusty conditions, using the oil bath style.

Air filters are quickly becoming the "what's the best oil to use" topic of the 2020's!

This comment makes me think that you didn't read my entire post, it seems like I've heard all this before....


I'm sure that you're aware by now that the "what oil do I use" question is engagement farming or Click baiting.... it's done intentionally... the people know when they ask that question what they're doing and it's to get people to follow, like, subscribe, comment and click, which makes them money through monetization.

[al's28/33]

Renner, I like your post. I too had an air maze for 15 years on my "A" with the steel screen, but kept thinking over and over, hey, the "A" never came with one, why add something just because everyone else has it and there was a sale from the suppliers ... besides I'm not driving on dirt roads or trailing behind a dust cloud, no reason to have it if the carburetor and all the other motor parts are working in synchronization.

[Werner]

That's how it looks. And then the engine runs perfectly with filtered air.

[JOES31]

It has nothing to do with the carb. Except getting dirtier by the mile.
Dust & dirt, and other particles are getting into your valve stems, guides, cylinder walls,
Rings. Of course Ford never used a filter. Engines didn't go that long anyways back then.
But now, they are and need the protection. What's the big deal anyways? Just run one to be safe.