Background: most people know that before about 1975 most IRON cylinder heads had "soft" valve seats. Once USA decided to remove lead from gasoline (and our air), the auto manufacturers started installing hardened valve seats in IRON cylinder heads. Hardened valve seats stand up better to unleaded gasoline in engines that get a lot of hard-driven mileage.
I've been led to believe that virtually all aluminum cylinder heads ever made... including especially ALL Buick, Olds and Rover "aluminum V8" engines (and also Buick 300) came from the factory with hardened steel valve seats standard.
Is it true?
I'm pretty sure that is incorrect. For instance, Triumph motorcycles used cast iron seats pressed into their aluminum heads. In some cases particularly with older engines, valve recession may still be a problem unless the seats are replaced.
Jim
I believe that the seats needed to be induction hardened to stand up to unleaded fuel. Even though the early seats may have been cast iron... it doesnt mean that they underwent induction hardening.
I've never heard that and I don't think it's true. The man who rebuilt my engine has done a number of 215s and he pulled and scrapped the stock seats and put in hardened. If I learn more, I'll post it.
Kris Palmer