8cm head specs

[doublezo]

hi. i recently had one of my heads milled. its now being hit by the #8 piston. just wondering, how thick are these heads stock, and how much is the max that can be milled away. trying to figure out where i am and how much the machine shop removed. thanks.

[Walt Dupont--Me.]

Usually .050 is the max you can mill those stock heads without the pistons hitting. Walt

[doublezo]

ok, .050 is the max that they can be milled. now i just need to find the stock thickness spec. anybody know?????

[Jack 34pu]

Not sure what you are asking. Measured from where? I have a set of 8CM heads that I measured the volume. 83-84cc's. I put a spark plug in and purchased a 100cc cow suringe from a local Tractor Supply. I found a small piece of sheet plastic (big enough to cover one cyl area and drilled a small hole in it. I used kerosene and filled thru the hole. Apply some vasolene or grease to seal the plate and set some weight on it. Make sure you have the head blocked level. Fill and measure. If you are way off from 83-84 cc's, your heads may have been milled by previous owner and your second milling was too much. I'm going to use EAB heads on my Merc - (64cc's)

[Ol' Ron]

What's important is the piston to head clearance. Milling to get.050" will increase the turbulence prier to combustion giving better throttle response and economy.

[doublezo]

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thanks for the replies guys. i guess im just trying to find out how thick stock heads were from the factory.

[rotorwrench]

It seems like somewhere on the HAMB there was a cut away through the dome area. They aren't real thick there from what I can remember maybe 0.25". I'd say definitely not much more than .3125". I don't know if Flatdog cut one up or not. I remember he cut an unrepairable block up so the port & cylinder wall thicknesses could be verified. I might be thinking about Barney Navaro too. He cut them long way so he could see how Ford did the sand casts for his own head production.

Kerby

[Big Shark]

Kerby, I have a stock 8cm head. I can measure it for you. Let me know before the weekend. Bruce

[Vergil]

Is this what you are looking for? 8BA

Hard to see but this head was .325".






Vergil

[Lawrie]

I have a cut up head ,it measured .258 in over the piston,and in the transfer area is .295 inch.
Lawrie

[JWL]

The Ford drawings call for .250 minimum casting thickness after machining. Of course the actual thickness will vary but should be .250, or more.

[Ol' Ron]

Why would anyone want to use a merc head. Low Compression.

[rotorwrench]

As far as the cast iron ones go it seem like the EAB heads are an inexpensive alternative to the aluminum high compression types. Mercs are like truck heads but you don't have to worry about pinging (detonation) as much thats for sure.

[doublezo]

Originally Posted by Ol' Ron

Why would anyone want to use a merc head. Low Compression.

its just what i have ron, thats why. i plan on changing heads and intake later. for now i just want my car to run again. also, thanks for the info on the heads everybody. i think i have what i need and yes the machine shop took to much off of the head. im gonna look for a set of the eab heads, guess i better look for a new machine shop too.