quattroworld

that will allow the use of bolt-downs? There's a difference between the two heads - there's a 'collar' that narrows the plug hole that's at a different depth in relation to the top of the plug, approximately a half-inch; that's preventing the bolt-down style from seating properly. I haven't measured the diameters yet to see if it could be forced; it seems like that 'might' be a possibility but I'd prefer to know if there were another option/solution first, or if in fact that's what can be done.


AMU - top of plug, about even with collar:


AEB; hard to see, but the plug is about 1/2" lower than the bore offset (collar):