To some of my readers, I know this is all meaningless gobbledegook, but to others, it's rich, greasy poetry. Marvel if you will, at the retro concept of crude engineering, cast iron, holes not drilled or milled by CNC, and, even wilder, only two valves per cylinder!
Argleblart! The swine! The recon head had some helicoiled inserts. Now I've nothing against helicoils, if they're done right they're tougher than the original thread, but dammit, one exhaust stud was out of alignment. Much filing ensued.