Quote:
Originally Posted by GordonP
I'm rebuilding an engine that has a significantly burnt first cylinder exhaust valve, valve seat, and even the piston is burnt closest to the valve. I had the same problem on my own Model A years ago.
I'm told unleaded gas is tough of the exhaust valves because it burns hotter. I have no data to support this, but the new valves are stainless, and stainless inserts don't burn like the stock block does in my experience.
I have no idea why it's always been the first cylinder. Maybe leaner?
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I fly an airplane with a tank in each wing and valve to control which tank feeds the engine.
The engine is equipped with a cylinder head temperature gauge on each cylinder and an exhaust gas temperature gauge on each cylinder. The engine monitor records those temperatures each second for later download and analysis on my laptop computer. I have flown with auto fuel(unleaded) in one wing and leaded aviation fuel (100LL) in the other. Switching tanks and recording the CHT and EGT I could never discern a difference in those temperatures whether on auto gas or leaded avgas.
Having regular access to leaded fuel I have never seen the need to put it in my Model A.