[Rich Biebel]

Solid bronze will seize up. I had it happen on my tow vehicle. Exhaust valve got hot pulling a hill and valve started to seize and bent hitting piston. Screw-in bronzewalls or thin wall types never a problem like that. They are softer and more self lubricating. They do wear more easily though. Cast iron guides also can easily seize. I honed thinwalls and screw-ins until the valve would spin free and never had one seize. Nice pictures and work on those heads. Makes me want to go back and do that work as I did for years.