Well good news. Made it to my local awesome salvage yard and I was treated to a pallet (yes, a pallet) of 6.9 heads. Sifting through them I came across two sets. One was labeled 87 6.9 and I noticed the rocker arm keepers (excuse me I don't know the actual term) were much more of a 90° than the ones I have from the first gen 83. The other set did not have a year written on the tag, but has the number "85" cast into the driver side head on the exhaust side between the 1st and 2nd exhaust port. Also worth mentioning, on the intake side of both head sets the bottom is a smooth straight cast vs my early 83 6.9 heads that have ripples defining each port. Tomorrow I will be returning with the tool to remove valve springs and check the valve guide play in both sets to help narrow down my decision. If I am not mistaken, do not the 7.3 heads have steel rocker arm keepers? Are the best year 87 6.9 aluminium keepers a better brand of lousy than earlier ones that look more bow legged out? Does any of this matter one way or another? I'll get pictures up asap.
I took a small scratch pad along and shined up the pre chambers and that small space between the valves and I can find NO cracks anywhere. I believe I understand why the guy said he got over 12lbs boost with no load. That pump is probably balls to the wall maxed out sounding like a proton pack. I know cracks in pre chambers are permissable as long as they don't breech the fire ring but for all of my pre chambers to be cracked and 5 out of 8 cylinders cracked between valves, something funky had to have went down. Possibly multiple times. Not watching the pyro? Pushing it too hard too quickly when cold? At least the pistons are in real nice shape. Again, I'll get pics up asap.
OI82