Posted by chriscase on Tuesday, January 02, 2007 at 13:57:37 :
In Reply to: Re: Valves posted by Vaughn on Tuesday, January 02, 2007 at 13:14:44 :
Hard seats are inserts, cut in by the factory or by a local machinist. "Hardened seats" came later. They are the actual head, flame hardened, or latest , induction hardened ('70's?). Seems cast iron has plenty of carbon to make it harden when flash heated. Easy to do a head at the factory with 4 flames. Takes just a minute.
I accidently hardened a Jeep block once, by heating a broken stud red hot. I used a battery and jumper cables. I wanted to take the temper out of the old stud so I could drill it out. Once things cooled, a drill bit wouldn't touch the block. It was a real pain tapping out the hole later.