fuel
Hi Guys,
I have no idea how many times I have heard the -must harden your valve seat talk - because there isn't any lead in the fuel. For engines of WW2 vintage this is not true for several reasons. First, engines of our period were developed to run without lead, Tetraethyl lead was added during the war to -boost- the octane level (more on that later) this was done to reduce engine knock/pre-ignition.
Secondly, the engines are of low compression and therefore do not generate the heat that one finds in modern (post-50's) engines, which could damage valves or seats.
Thirdly, the lead salt deposits actually damage the valve stems and can foul spark plugs; decoking was common practice in part because of this.
Now, back to the octane boosting, when the octane level is increased the burn rate of the fuel is actually slowed down. Think of it like this, a low octane fuel will burn -very- quickly, the resulting explosion will drive the piston down quickly as if struck down by a large hammer. Whereas a high octane fuel will burn slower and the resulting explosion will push the piston down as the fuel is still burning. This means less pressure and stress on your old toy.
By-all-means add an octane booster to your fuel, one with a top-end lubricant is also cheap insurance for flathead (valves in block) types. I have an Indian 741 and it runs so much better with a drop of Blendzall gold. My Daimler also runs better with a mix of the above product, though it is OHV so the top-end lube is probably overkill but she runs fine. If you feel you must add lead then go ahead but just be aware of what is going on.
Cheers,
Dave
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