Sorry for the delay but now the guy is swimming in an ISO audit and may not get to it for another week or two. I see him every day and the equipment is always available so it will get done. In the mean time I have put together a starting point for him to digitize from based on the following dimensions on the intake side which I would like someone to confirm on another 848 head.
Port center to center distance = 8.562” Alignment ring bore diameter = 1.562” I.D. of alignment ring installed = 1.414” Alignment ring bore depth = .188” Bore diameter @ .188” deep = 1.437” (45 degree bevel transition from this point to cast bore) Intake runner diameters: Min. found = 1.340” Max. found = 1.395” Inconsistent all around but no more oval than .03” at any point. Runner diameter continues in to a depth of 2 ¼” where it widens into bowl.
It would appear one would be able to generate a “hill” with the material available but where is the jacket and what kind of minimum wall thickness should there be?
If opened to 1.5” on the intake side the alignment rings would be eliminated. How to address this? Cut a bigger step in the head and intake for larger rings? Dowel the intake and head as an assembly? Ignore it and try to align by eye? How big is the hole in the gasket?
As far as opening up the area behind the valve what kind of radius into the bowl would be most beneficial? A lollipop cutter could do wonders there to generate a smooth curve from the valve seat into the bowl.
