Model A "B" Police Head Information + Carburetor

[Alex Dragone]

I recently came across a police head with the "B" cast into the top of it and I would like as much information as I can get on the head. I would like to put it on my Deluxe Phaeton 180 A. Would it give me better performance? Will I see a difference in top end speed? And on Hills? How does this compare to a stock model A head? Also Does anyone have any historical info on these heads? Were they actually used on police cars? Lastly, what is the best carburetor to use for best performance? Tilliston model X? Zenith etc... Any thoughts on this? Thanks!

[Hicktick]

Alex if you will use the search feature at the top and search police head you will find many discussions on it .

I am sure others will comment with their knowledge of your questions .

[Alex Dragone]

Hicktick, Thanks! I have viewed most of the discussions on this head and still would like more information on them. I also forgot to ask, how this head compares to the new aftermarket high compression heads available today such as the Snyders 5.5:1 head?

[1930artdeco]

I think the Snyder head gives a bit more compression if I remember correctly. But, I put a Snyder head on T.S. which outweighs your car by several hundred lbs. I routinely cruise at 50 mph with a Zenith that runs a bit rich on the freeway. So that should give you an indication what your car will do.

Mike

[Purdy Swoft]

The police head is 5.2 compression ratio. It will add torque and hill climbing ability. Higher compression will slightly increase R.P.M. and top end. If all other things are right, it will slightly increase M.P.G. You should notice a day and night difference over the original 4.22 head , in hill climbing and driveability in general. It won't perform as well as the 5.9 heads that are no longer produced but it is well worth the effort. I think that the police head was offered in 1931 after tetraethyl Lead was added to the gas so as to prevent most timing knocks. I think that the heads were first available for police use only and were later offered as an option that could be purchased. The model B Zenith will outperform the model A Zenith 1 or 2 but will perform better if the intake manifold runner is enlarged to model B size. Acording To Richard Lorenze flow test featured in the Fast news letter around 2002 or 3 , the Tillotson model X out flows the Zenith 1 or 2 . I would prefer any cast iron Zenith or Simmons carburetor over any pot metal carburetor because of warpage and vacume leaks. My preferance is a dual up draft cast iron intake manifold with dual model B Zenith carbs. This works good for me, you still have the ability to use the original choke and G.A.V. adjustment and use the same cranking procedure that you would use with any updraft carb setup. You will probably get more top end from a down draft or Weber carb setup but they are harder to set up and not period correct.

[H. L. Chauvin]

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FWIW, for engine performance, besides trying different heads, different carburetors, etc., etc., in speaking to Mr. Ron Kelley a few years ago, (who adveritses in "The Restorer"), and who published several Model A reports on dynamometer results obtained from recording these results from his different Model A modifications, he mentioned that one amazingly easy & inexpensive way to increase engine performance he found & proved with recorded dynamometer test is do what performance engine builders recommended for years; i.e., to increase engine air flow as follows:

1. Provide porting as recommended for competition racing engines; for example, remove & slightly polish cast iron sharp edges inside the cast iron intake ports of the Model A engine. Do not cut too deeply -- the intake casting is not super thick.

2. On valves, remove the sharp lip on bottoms of valves & very slightly round the sharp edge above & below the valve's valve seats; and also remove sharp edges on bottoms of newly installed harden valve seats in the engine block.

3. Remove sharp edges & slightly polish insides of intake manifold at both ends and also at the inside curves.

4. Check carburetor/intake manifold gasket & enlarge center opening if it protrudes into the intake opening. Very alignment of intake/engine manifold gasket such that this gasket is not protruding into the intake opening.

5. Check inside of the carburetor venturi & "if" it has a sharp casting lip inside the opening, make it smooth.

He noted how he found it amazing that such simple inexpensive modifications could greatly increase engine performance as witnessed by testing each step with his engine dynamometer as opposed to just "feeling" or "assuming" these differences while driving on the highway.

[Alex Dragone]

Thanks H.L. and Purdy for the great info. I like this head because it was an original add on. My car is an extremely original 180 A so I dont want to put any un-original parts. The B head is great seeing how my car is a late 31. Does anyone think that milling the head for higher compression is a good idea? I will probably have to anyway to make it flat. But how much can I take off (assuming the head has not been milled before)?