The Ford Barn

old28 · 10-21-2016, 02:08 PM

Got a friend that picked up a Model A police head and wanted me to get some information on the head. This head as made was 5.22 CR and had a flycut for the piston pop up in the head.

Will the head chamber take 1.7" intake valves?

If used on a 4" bore motor with 0 deck & .052" crush head gasket how much can be milled from head face surface to increase compression ratio a point or point and half (6.22 - 6.72)?

Capt Quahog · 10-21-2016, 07:56 PM

Way back in the late 1960s, I acquired a blue 1930 Ford tudor sedan that had been purchased by the City of Fitchburg, Massachusetts in a fleet of new police cars. That automobile was that fastest Model A Ford I for one have ever owned or driven. Until modern times, the existence of a "police head" for Model A Ford cars was unknown to me. Have since speculated whether or not that old Ford may have had one of those type heads factory installed . . . If so, then such an item would no doubt enhance the speed of a modern day civilian's Model A Ford car.

Dodge · 10-21-2016, 08:04 PM

Wont take the big valves, combustion chamber not great for going that high on compression. That head is great for a stock motor, but for a hop up get a proper head.
It's breathing as well as compression.
My 2 cents.

old28 · 10-22-2016, 12:19 AM

Dodge ---- I'm not an expert on model A stuff but what you said was what I told him might be the case. A good old used head for a stock motor, but with 4" bore, big valves & 2x2 intake he would be better off with one of Tod heads that would have a little more compression and flow better.

PC/SR · 10-22-2016, 01:10 AM

What Dodge said. Get a head designed for that CR. Then check measurement for bigger valves and after you get the valves in, including Tod's heads. Have not seen anything about bigger valves on his heads. But, no matter what, measure anyway. Get a couple of tubes of Prussian Blue. If you do not assemble or measure it yourself, hope for the best.

Kurt in NJ · 10-22-2016, 08:34 AM

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most of the "B" marked police heads that I have seen have a crack through the center, I don't think thinning the gasket surface will help that tendenacy

old28 · 10-22-2016, 01:34 PM

PC/SR ---- We are both old drag racers, built our own motors, and have done lots of clay measurements. As we have never worked on an A motor we will check everything 2 or 3 times and continue to ask questions. Hang with me and thanks for all the information & replies.

Kurt in NJ ---- This is a nice old "B" police head. It has been Maged & Pressure tested. I think he may go more into a stock motor build and use this head.

10-21-2016, 02:08 PM	#1
old28 Senior Member Join Date: May 2012 Location: Camarillo, CA Posts: 288	Police Head Got a friend that picked up a Model A police head and wanted me to get some information on the head. This head as made was 5.22 CR and had a flycut for the piston pop up in the head. Will the head chamber take 1.7" intake valves? If used on a 4" bore motor with 0 deck & .052" crush head gasket how much can be milled from head face surface to increase compression ratio a point or point and half (6.22 - 6.72)?

10-21-2016, 07:56 PM	#2
Capt Quahog Senior Member Join Date: Jan 2016 Location: Barren windswept mountain somewhere in bleak Northeastern Pennsylvania Posts: 294	Re: Police Head Way back in the late 1960s, I acquired a blue 1930 Ford tudor sedan that had been purchased by the City of Fitchburg, Massachusetts in a fleet of new police cars. That automobile was that fastest Model A Ford I for one have ever owned or driven. Until modern times, the existence of a "police head" for Model A Ford cars was unknown to me. Have since speculated whether or not that old Ford may have had one of those type heads factory installed . . . If so, then such an item would no doubt enhance the speed of a modern day civilian's Model A Ford car. __________________ I wouldn't be so paranoid if people weren't plotting against me all the time

10-21-2016, 08:04 PM	#3
Dodge Senior Member Join Date: Nov 2011 Location: Sonoma, CA. Posts: 1,495	Re: Police Head Wont take the big valves, combustion chamber not great for going that high on compression. That head is great for a stock motor, but for a hop up get a proper head. It's breathing as well as compression. My 2 cents.

10-22-2016, 12:19 AM	#4
old28 Senior Member Join Date: May 2012 Location: Camarillo, CA Posts: 288	Re: Police Head Dodge ---- I'm not an expert on model A stuff but what you said was what I told him might be the case. A good old used head for a stock motor, but with 4" bore, big valves & 2x2 intake he would be better off with one of Tod heads that would have a little more compression and flow better.

10-22-2016, 01:10 AM	#5
PC/SR Senior Member Join Date: May 2010 Location: Santa Rosa, CA Posts: 1,279	Re: Police Head What Dodge said. Get a head designed for that CR. Then check measurement for bigger valves and after you get the valves in, including Tod's heads. Have not seen anything about bigger valves on his heads. But, no matter what, measure anyway. Get a couple of tubes of Prussian Blue. If you do not assemble or measure it yourself, hope for the best.

10-22-2016, 08:34 AM	#6
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,159	Re: Police Head Sponsored Links (Register now to hide all advertisements) most of the "B" marked police heads that I have seen have a crack through the center, I don't think thinning the gasket surface will help that tendenacy

10-22-2016, 01:34 PM	#7
old28 Senior Member Join Date: May 2012 Location: Camarillo, CA Posts: 288	Re: Police Head PC/SR ---- We are both old drag racers, built our own motors, and have done lots of clay measurements. As we have never worked on an A motor we will check everything 2 or 3 times and continue to ask questions. Hang with me and thanks for all the information & replies. Kurt in NJ ---- This is a nice old "B" police head. It has been Maged & Pressure tested. I think he may go more into a stock motor build and use this head.