Gday Rabs,
Just wondering if you bought your heads complete from COME racing or did you buy them bare?
If you bought them complete,did you have them checked out be fore fitting them up?
I found a heap of issues with the complete 600 series heads that i bought,form hour glassed valve guides to seats being .030" different in height.The stud holes for rocker studs weren't even tapped far enough for the studs that were supplied.Ended up having to swap out springs,locks and retainers to get them to work with .660" of cam lift.
I also had a few issues with the 396 kit. While not far out,the balance was up to 20grams out to the figures that came with kits.Rod bolts galled in the rods.
Hope you didnt have any of the issues i had,but just because your buying from a supposedly reputable company doesnt mean they'll be right! i suppose it buyer beware as usual!