Measure the thickness of the outer head bolt bosses and see how thick, tall, they are now and please post them.
I'll bet a nickel they are closer to .960 to.950 now than they where new
I'll do that if my memory cooperates. I wish I had cc'd them before sending them out to be machined, just to have the data. What do you guys suppose unmilled open chambers cc at? 95?? 100??
My 906 heads measured out at 92cc.
How thick are the outer head bosses now?
I had a set of "516" close chamber heads converter to 1.74 exhaust and some bowl work done for a 440 bracket motor years ago, I ended getting a use set of 906 heads that had some poring work and bigger valves in them and swap them onto that motor, I ended up checking the CC on both sets of heads while doing the swap and the 516 had right at 90.0 CC and the 906 had right 74.0 CC
The 516 set had taller outer head bolt bosses than the 906 did
I ended up learning from that you can tell if a heads has been cut very much based off of the head bolt boss thickness
EDITED: One of the older Mopar HP bible section on BB stated that to remove 1.0 CC form a open chamber head like the 906 to remove .010, I think, from the head surfaces for each CC and to remove .012 from the intake side of the heads to keep the intake manifold fitment correct
I should have dug that book out before posting this but I can't remember which book and where all those books are stored now, CRS
