Larry,
Let's say your timing curve is correct, assuming correct springs and advance
weights, and nothing is sticking or hanging up. In cooler weather, does the
pinging
persist? Have you tried a colder spark plug? If the "Summer Plugs" do not cure
the
problem, try richening the mixture a step or two. The coldest plugs that do not
"foul" are usually the correct plugs for your particular engine. Back when I was
tuning a friends 67 XK-E, (1975 or so), I found the recommended racing plugs
worked.
However, I had to tell him to drive it like the sports car it was rather than
lugging it to keep the plugs clean. By the way, The Jag was the high
compression
version with a 9 to 1 compression ratio. On today's fuel, 9.7 to 1 may only work
well with computer injection and spark controls. Or, you could go to a racing
fuel
or octane booster. Note that aviation fuel will not work well.
Good luck and keep the shiny side up,
Mike Dwyer
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