Fellow Floggers-
I have been chasing a high speed miss all season. The Duke will pull the
lower gears as far as I dare, but on the straight in top gear, anything over
about 5000 -> 5500 will end up with a very unhappy motor, missing and cutting
out. In fact the miss was so bad the whole car was vibrating and shaking. It
was evident that the miss was a lean out condition at the higher revs, but
why? I tried the usual, higher floats, higher fuel pressure, softer mounts on
the carbs (I got them so loose I think they actually lifted up into position
only when the engine ran...), and fatter needles. Nothing really worked and I
knew that whatever it was, it was something other than the engine.
Today I was checking the front end and realized that the rotors were so far
out of balance that they would spin around and always stop in the same spot!
Thirty or forty years ago I found that Brembo rotors were pretty bad in that
they would wobble all over the place when installed, so I never used them.
Today half the cool cars around have some sort of Brembo "big brake" kit on
them, so when Moss sent a set of Brembos I Froze them, mounted them up and
the runout was pretty good. What a fool, I never checked them for balance.
Early on I had even rebalanced the wheel/tire setup, but again never thought
about the rotors, but from the amount of misbalance I found on these puppies,
I think that what has been occurring is that the rotors were so far out that
they would vibrate at top speed and foam the fuel in the carbs and lean out
the motor to such an extent that it would fall all over itself at high speed.
I have installed an old factory set of rotors which seem to be spot on,
balance wise, and we will see what happens at the next outing...
That's my story and I'm stickin to it...
A little off balance myself...
Nick in Nor Cal
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