[ShovelOwnerMaintained]

I have a set of very early Evo heads
84 A's. The combustion chamber is D shaped.
I have another set manufactured in 90? and they are 84Cs. The combustion chamber D shaped, but on both sides of the combustion chamber.
Both are crankcase breathers.
so what's the difference between these heads ? Does the later one have less CCs ? Does the later one flow better ?
Please, no guessing, I need a definitive answer. Thanks in advance ?

 

[Turboprop]

Worthless without pics..

 

[Thermodyne]

I have a set of very early Evo heads
84 A's. The combustion chamber is D shaped.
I have another set manufactured in 90? and they are 84Cs. The combustion chamber D shaped, but on both sides of the combustion chamber.
Both are crankcase breathers.
so what's the difference between these heads ? Does the later one have less CCs ? Does the later one flow better ?
Please, no guessing, I need a definitive answer. Thanks in advance ?

All oem evo heads use the same chamber. So the set with the laid back wall have been worked on.

 

[autoworker]

I know that the very early heads were sand cast and later heads were die cast.