I read on the "FAQ Olds Engines" site that the "G" series ('71) heads "possibly" have hardened exhaust seats due to Govt. regs about unleaded fuel use. Do only some of the "G" series heads have hardened exhaust seats, or do all of them have the hardened exhaust seats? I also read that the engines running w/o hardened exhaust seats on unleaded fuel wouldn't see much more than 60,000 miles, as the lack of padding f/ the exhaust valves would cause sealing failure.
My 455, an untouched '71 model w/ "G" series heads, has 93, 900 miles on it and runs perfectly. Should I assume that the heads have hardened exhaust seats due to the fact that the engine, after nearly 100,000 miles on it, still runs well w/ no evidence of head problems?
I don't plan on taking the engine down any time soon, as it runs so well and burns no oil. I'm only curious as to weather or not these "G" series heads f/sure have the hardened seats.
Thanks in advance f/ any info.

 

Jim, my 71 Olds 98 had about 90k miles on it when I bought it and the 455 with G heads ran like a champ. We've discussed hardened valve seats many times, and I think the consensus is that you should install hardened seats if you decide to do machine work to the engine, otherwise, run the lead additive only if it gives you peace of mind. There are many members on our board that run non-hardened valve seats in their Olds without lead additive without any problems.

FWIW, I'm not sure if the G heads had hardened valve seats.

 

Yes, my '71 owners manual says that ALL 1971 GM cars are designed to run on un-leaded gasoline.

 

As noted, all Olds V8 cylinder heads from the 1971 model year on have induction hardened valve seats. Note that induction hardened means that the cast iron parent metal was locally hardened around the valve seat area. These heads do not have separate pressed in seats.

 

I have 1972 GA heads with factory pressed in exhaust seats; the heads came with 2.07" intake valves and 1.63" exhausts. I have had other GA heads with 2" intakes and 1.68" exhausts that had induction hardened exhaust seats. The casting change near the seats beginning with E heads in 1970 gave better "ramps" to the seats and also provided additional cast material to allow easy machining for pressed-in seats.