How a Model A Engine Breathes.........

1. A paper filter (no matter how large) can be soaked with gas. Then one backfire can start a fire. Of course you can install one of those high rise filters that look like a WWII u-boat snorkle. The only problem with that is. . .UGLY!

2. There is no doubt that good filtration will reduce engine wear and increase engine life, however in my case (and the case of many fellow barn members) my engine will certainly outlast me - even without any filter! :eek:
 
There is some confusion, those little, add on paper filters are NOT an Air-Maze & they are very restrictive to air flow. The TRUE Air-Maze is wire mesh & NOT restrictive. Their main function is a FLAME trap, to prevent FIRES, when you get a "cough" back, out of the carb.
Those LARGER paper element filters Like Carls', that mount high above the rear of the engine, work VERY well & are safe from burning.
On those little, hang down filters, you can buy a longer center bolt & a longer filter element, but there's still the FIRE danger from carb dribbles.
Ol' Henry didn't put filters cuz at the time, he DIDN'T know how IMPORTANT they were!!! Just pay attention when you BLOW your NOSE, & think of how MUCH stuff gits SUCKED into Yo' ENGINE & GRINDS away the PISTONS/RINGS/ETC!!!
Would someone please post a pic of beating that DEAD HORSE, again?
Bill W.
 
BILL WILLIAMSON said:
Just pay attention when you BLOW your NOSE, & think of how MUCH stuff gits SUCKED into Yo' ENGINE & GRINDS away the PISTONS/RINGS/ETC!!!
Bill W.
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My K&N Filter MUST be filtering SOMETHING. Otherwise I wouldn't have to clean it all the time!!:cool:

And I can honestly say it has never been "Saturated with Gas". :eek::eek:

BILL WILLIAMSON said:

Would someone please post a pic of beating that DEAD HORSE, again?
Bill W.
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Now where did I put my DEAD HORSE beating stick... :rolleyes::rolleyes:
 
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I live in a small town but no dirt roads. You'd be surprised at the amount of airborn dirt and sand that settles in my pool every day. I have the K&N "snorkel" type Snyder's sells on a Marvel Schebler and runs great.
Hugh
 
I have the old Air Maze mesh filter that I upgraded by spraying with K&N filter oil. Can't hurt, looks vintage, and engine runs good.
 
Breathing refers to air entering the carburetor, mixing with gasoline and flowing into the engine via the intake manifold, and intake valves. The more air+gasoline mixture that can be put into the engine, the more power the engine makes.

It stands to reason that if anything is put into the air+gasoline flow stream, breathing is reduced. So adding any kind of air filter into the breathing system reduces the air+gasoline flow into the engine, thus reducing its power.

When the Model A was being designed, Henry Ford was interested in its low cost of operation, especially by having excellent gas mileage. So the Model A was given a small carburetor to assure that the Model A had good gas mileage at the expense of higher power production.

The best power increase for the buck is to put a larger flow carburetor on the Model A. Ford did this in 1932 on the Improved 4-Cylinder Engine.

By the way, breathing flow is measured in cubic feet per minute (CFM), and so to are carburetors sizes measured in CFM.
 
CFM is measured in inches of vacuum on a U tube manometer filled with mercury - HG. Manufacturers of speed equipment and shops that do port and valve modifications Didn't specify what vacuum they used to measure air flow in the 1970's when I worked in the motorcycle racing business. Suck harder, higher vacuum, and you get better numbers for your sales brochures ! Things may be more standardized now, I don't know. We used 12'' HG because that was what most manufacturers used ie. Ford & Harley. There is an equivalent to the 12'' in MM and that may be more the standard now if in fact there is a standard now. Also laminar flow benches ARE the std. for real flow benches, Most are orifice types and are not nearly as reliable.
 
Any kind of filter put into the intake side of the breathing system of the Model A reduces power production of its engine.

Devices that have intake air filtering have breathing systems designed to correct for the flow restriction, and carburetor jetting / reeds sized for a proper air-gasoline ratio to run the motor efficiently.
 
Bob Bidonde said:
Devices that have intake air filtering have breathing systems designed to correct for the flow restriction, and carburetor jetting / reeds sized for a proper air-gasoline ratio to run the motor efficiently.
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Perhaps it is only the early V8 guys that noticed that Ford added a tube to equalize the pressure in the float chamber to that inside the air filter to correct for the flow restriction that Bob refers to. That change is part of the evolution of the Holley 94 and beyond. I added such a tube to a model B carb. Might be useful to those whose carbs suck in a lot of rocks. Good Luck: Fred A
 
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