Creamie,
I have the greatest of respect for John Deacon, but nobody is always correct about everything, unless you want to believe that "big oil" and "big auto" ran a con job on exhaust valves world wide.
What would the motive have been, unleaded was a done deal. Why would OEMs now be offering cylinder kits "suitable" for unleaded, if any of the P/Ns could run on unleaded for a normal overhaul life --- another big con job???
That FAA tests proved no change as described by Deacon, (you are a lawyer) didn't disprove the problem with exhaust valves and seats, because there is no information about the material used in the valves and valve seats of the "test" engines.
I have considerable experience with "old" auto engines, particularly Jaguar XK series --- it is quite remarkable how rapidly old material seats "hammered" or recessed withing a few thousand miles with unleaded. Equally, such problems ceased when we rebuilt heads with Jaguar supplied replacement seats and valves.
Old Holden "grey" motors were a particular problem, the early "Holden" 5L and the 350 Chev derived engines of the era also suffered, even with "lead substitute" additives.
This isn't my imagination, it is all a matter of records.
Tootle pip!!
Last edited by LeadSled; 2nd Aug 2013 at 06:47.