Quote: So taking a 440 (10:1) with 906 heads, popping em off and putting on Eddy heads would lead to problems?
Problems? No.
HP loss ... hard to say. If you were comparing two IDENTICAL castings where the only difference was cast iron vs aluminum then there might be a HP loss with the aluminum because of heat loss.
However, there is no aluminum head that is a plain ol' copy of an iron head. Even the base 440Source head flows better out of the box, has larger valves than stock and will provide higher compression with its closed 80cc chamber design.
There's no reason bolting on any aluminum head should cause any power loss unless the head is a clear mis-match to the application - like bolting a B1 head on a stock 440 !!
