What head is this?
 

Can anyone tell me about this?
It appears to be a 5.2:1 head but it does not have a "B" cast into it.

Re: What head is this?
 

Is a high comp head! Made in the good ole USA. Clean it up good inside and out and use it!

Re: What head is this?
 

Looks like a police head, wonder why it isn't marked with a "B" See info.
https://www.fordgarage.com/pages/hea...ssionratio.htm

Re: What head is this?
 

Yeah I was on that site earlier looking for info.

Re: What head is this?
 

Aftermarket head more than likely. But still Hi compression.

Re: What head is this?
 

As Vince Falter's most excellent web page notes (see Stickshift's post #3) there are a lot of aftermarket heads. I have a "Model A" aftermarket head on my '31, which apparently came in both 4.2 and 5.2 configuration. I pulled the head off last week to change the head gasket and sure enough, I have the "high compression" version. I put that in quotes because a 5.2 compression ratio ought to put cylinder pressure somewhere in the 70's psi. Well, I have 80s and 92 in one cylinder! I suspect that the block and head have been decked sometime in the past, the engine is 0.080" overbore so it likely has been rebuilt at least twice and the block possibly decked each time. The head appears flat, I used a 0.003" feeler gauge and a straightedge and could not get it in anywhere, either lengthwise or crosswise. So I'm going to put it back together (after I get the broken stud out, of course...) and run with it.

JayJay

Re: What head is this?
 

Most likely the head listed as "F2 MF" on the spreadsheet list. Copy of a Ford 5.2 A-6050-B police head.

Re: What head is this?
 

I have a Brumfield. So how do you measure these things for compression ratio?

Re: What head is this?
 

Re: What head is this?
 

Y-B has given the definition of compression ratio. Practically speaking, most folks simplify it as

*measured compression test pressure divided by 14.7 = compression ratio.

So the "standard" psi of say 62 psi would be 62/14.7 = 4.22 (round to 4.2). And a 5.2 head would be around 75 psi on a compression test.

JayJay

Re: What head is this?
 

Re: What head is this?
 

I agree completely. I'm not suggesting to use it, but it's simple and what a lot of folks can relate to easily. That method doesn't account for the difference between absolute (the 14.7) and gauge (what you measure) pressures, for example.

And the 14.7 only applies at sea level.

JayJay

Re: What head is this?
 

So after leaving the head in a rust911 solution for a day and cleaning off I think I know why it was sitting on the shelf. It has cracks across the top of the head and I don't trust it enough to try it out.

Re: What head is this?
 

Looks like freeze cracks to me. If there is no other cracks I would solder them up and give it a try.

Re: What head is this?
 

I thought about grinding out the cracks a little and using some JB but I'm worried about the crack near the #2 spark plug especially with the higher compression.

Re: What head is this?
 

5.2? How about a Winfield red head? 7.5 to 1…she’ll pull your hat clean off your head.

Re: What head is this?
 

Thanks Jay Jay

Re: What head is this?
 

Plus, cranking speed varies, ring seal may not be very good, valve timing varies (affected by lash), ambient temperature and coolant temperature vary, etc., so the compression gauge method is a waste of time!

Re: What head is this?
 

And let's add - overbore increases cylinder displacement relative to combustion chamber volume.

All in all, a lot of variables. That many degrees of freedom makes the engineer in me cringe. Having said all that, it's an attractively simple formula. And it's at least qualitatively correct - compression ratio and cylinder pressure do co-vary.

I think you, Y-B and I all violently agree.

JayJay

Re: What head is this?
 

I have a red winfield been tested and resurfaced is ir worth much> had fir 50 yeara,