Kenneth,
I thought hardened valve seat came into production Olds in
'71 or '72.
It was in '72. That's what the addition of the small capital letter
A behind the 7 (sbo) and G (BBO) heads means.
I know what you're saying. I've read it before. But I can guarantee you that
Gary Kimball and John Steinhauser in our speed shop machine shop and Dale
Korneman and Jim Jennings at Kahan Chevrolet never saw alloy steel ring
hardened valve seat inserts in any GM head in the early '70s. I didn't see
them, either, in all of the Olds heads that I handled. As for the flame
hardening to the stock valve seats in the cast iron heads, we could rarely
see the carbon blackening around the valve seat, and that was only in
mid-'70s heads. I can't tell you the precise years, but in our experience,
the flame hardened cast iron seats weren't near enough to protect from the
valve slamming closed abuse on the valve seat, when only alloy steel intake
valves were still used. Only when GM finally switched to stainless steel
intake valves did that problem go away, which was also about the same time
alloy steel hardened valve seat inserts were finally installed, like they
should have been from DAY ONE!
Without the lubrication and cushioning effect of the Tetra-Ethyl Lead in
automotive gasoline, the valve seats were dead meat.
I simply can't believe '72 Olds heads had a flame hardened cast iron valve
seat. We will have to agree to disagree. I would need to be shown a '72 Olds
head with the telltale flame hardening carbon marks to believe it. I can
also guarantee the first valve job on a GM head will most likely
***remove*** that flame hardened surface from the cast iron valve seat on
heads so treated. The flame hardening of cast iron valve seats was one of
the worse shams that GM ever pulled off to abuse the car buying public. The
worse was in telling buyers of '71 GM vehicles to, "go ahead and use
unleaded gasoline in your brand new '71 GM vehicle. It won't hurt a thing."
Yeah, and I've got a bridge in Yuma, AZ, I need to sell you! GM learned that
lesson real quick with massive warranty claims for '71-'72-'73 engine valve
jobs after only 10K-30K miles. I was there. I saw it. GM didn't start to get
a handle on premature valve jobs due to the use of unleaded gasoline until
the '74-'75 model year engines. That still doesn't explain why my '76 350
Impala, which I thought would be safe from the unleaded gasoline valve
problem, lost 4 intake valve seats at the same time!!! But my Impala's 350
didn't have stainless steel intake valves. GM wasn't using them, yet.
Milton Schick
1964 442 Cutlass
All ultra highly polished stainless steel valves running on cast iron valve
seats, and she runs plenty of lead in her gasoline.
[EMAIL PROTECTED]
