Re: Cracked block- how serious is it?

Posted by PackardV8 On 2011/7/26 20:30:18

I'll second that David M about the valve seats.

I was a bit alarmed some 8 or 10 years ago when i received SS valves from a vendor. At that time i had not ran any SS valves in anything. Urban legend (albeit rather recently) has touted hardened seats for SS valves. Of course we're assuming castiron here not Al heads. They seem to run just fine.

A different engine i've ran for over 40 years every year at speeds alot higher than it was designed for and runs hotter than ANY automobile engine including racing engines got SS valves for the first time about 6 years and 9K miles ago. NO hardened seats. THis engine requires rings and a valve grind about every 5K miles or every time i change the rear tire. So i've had it apart twice in the 6 years for inspection. NO valve recession whatsoever.

The hardened seats are necesary for Al heads or damaged heads. OTherwise the hardened seats are just 'make work' for the machine shop.

BTW the intake valves of the Indian engine set extremely close to the bore even with std bore. I would sure hate to weaken that any at all. I've seem many where the seats cracked over into the bore just due to overheating.

Overheating or other extreme demands can cause any insert to work loose. On the AL heads the hardened seat is locked in during the casting process.

Bottom line, the hardened seats for water cooled, CI, passenger car and lite truck engines is just one more mahine shop 'make work' gimmick on a par with milling every head that comes thru the shop wheather it needs it or not..