[Scott Fisher talks about lead and valves...]
As I recently bought an old LandRover, I'm very interested in this
discussion.... Do we have first-hand case stories of unhardened
valves and seats *not* eroding in 20-30-40K miles or more with
modern unleaded fuels?
Some questions for my particular situation: For a given ignition timing
will there be a significant temperature difference between high and
low octane rated fuels? I can hypothesize arguments for all three
possible answers. Does anyone actually know?
Could the situation for low compression engines actually be worse?
As there is less expansion after ignition, there is less PVnRT cooling
before the exhaust valve opens so I imagine the exhaust stream in
a low compression engine could be significantly higher than in a
relatively high compression engine.
Hypothetical change: what if one were to retard the valve timing
some small amount... By opening the exhaust valve later, would
conditions be such to increase valve life?
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