eab vs 8ba heads

If all components are up to the proper specifications, the change should increase the compression ratio from 6.8:1 to 7.2:1.
 
I understand that EAB are the heads to use, much better than the Merc heads..and in the OLD days I pitched them for the Mercs!!!!Newc
 
The Merc EAC heads have a larger combustion chamber than the Ford EAB heads, EAC=75-77 cc and EAB=70-72 cc.
 
FoMoCo wanted the 255 to have the same compression ratio as the 239 and the only way to do that was increase the clearance volume.
 
Funny how some people use Merc heads on an 8ba with a 3 3/4" crank thinking that Merc heads mean better performance. Not.
 
8BA heads, when milled .050, deliver almost identical C.R. as EAB heads. However, there is also a small difference in the transfer area design.
 
When I was doing my Flow bench work I made up a wooden head and with all kinds of combustion chambers and tested them all looking for the "Holy grail" of flow The transfer area is interesting, by changing the angle of it it increased flow untill about 12 degrees, Unfortunately the castings were too thin for this angle so I use the Offy heads (thicker casting) to make my chambers and use an 8 deg transfer angle. un fortunately this reduces the CR some. Every little bit helps.
Gramps
 
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