Lead additive?

[johnnymcl]

I have a 1947 flathead V8 Mercury that I just purchased. Do I have to add a lead additive to the gas?

[65comet]

It depends on if it was rebuilt in the last 30 years with updated combustion chamber valves. The old style valves are what require the lead additive to keep their edges from pitting and wearing away. It won't hurt the newer valves to put the additive in. At my families construction company we had some old cranes from the 40's powered by Industrial Chrysler Hemi's. The 500 gallon tank we fueled them from got lead additive and all the construction vehicles and small equipment that used gas got filled up from the same tank.