[Healeys] Octane ratings

[Healeyguy]

Steve
In the old days valve jobs were simply a resurfacing of the valve and cutting the seat. Valve jobs or decarbonizing were also very cheap.  The end result is a deeper seat and a thinner valve. Result, the head appears to have valve recession. With our current thinking that "I only want to do this once more in my lifetime," we replace the valves and just about everything else and insist on addressing those deep seats. Result, like new appearance and a much bigger repair bill. As an aside, some heads are tolerant of deep seats and some crack like fried marbles. AH 100 heads are prone to cracks (in various places), six cylinder heads less so. Also remember that replacement valve seats are not fool proof (good machinists or not so good, overheating, etc) and can come lose during use. Not often but neither is the failure rate with deep seats. Just a few thoughts....
Aloha
Perry



In a message dated 10/02/09 13:09:48 Hawaiian Standard Time, sbyers at ec.rr.com writes:
Mike, when I had my BJ8 head rebuilt, the machinist told me that I had 
significant valve recession.  He showed me my head, in which all of the 
exhaust valve faces were flush with the adjacent head surfaces, and a 
rebuilt head from another type of car where the valve faces were 
significantly proud of the head surfaces.  When I got the head back, the 
valves were like the other head. 
I haven't seen any Healey engine head but my own, so I don't know.  Was my 
machinist correct or not?