Skip---I doubt that Illinois much cares that your 250 has all of the
smog equipment in place, given the impact of so few cars on the entire
picture. Even here in fussy California, such cars are now exempt from
the bi-ennial tests for compliance.
So far as I know, there are only two kinds of distributors for the six
cylinder TR. One has both pots that gives a mix of retard and advance,
depending on throttle position. This is what your car had when it left
the factory. The little trumpet valve that connects to the end of the
throttle linkage supplies vacum to the retard pot when the throttle is
closed, and retards the timing. As you press the throttle, the valve
interrupts the vacuum retard, and the vacuum advance begins at varying
degrees, again depending on throttle position and engine load.
I suspect the one you have is the later distributor that has vacuum
retard ONLY. You can test this by connecting any operating vacuum line
to this pot, and using a timing light. Vacuum will retard the timing.
Usually a dwell meter won't pick up a bouncing distributor, but a timing
light will. The cause of such bouncing can be from any or all of the
following:
Worn bushings in the distributor.
Loose or worn timing chain (esp. the single chain version, as the early
sixes)
A bent distributor shaft, near the cam that opens the points. (common)
I have yet to see a TR that does not bounce at least two degrees at some
point along the curve. This does not mean it won't run well. While it is
a worthy project to make things "right", don't look for any performance
gains in doing so. Most engines run well with just the centrifugal part
of the ignition advance set and working properly.
Dick Taylor
'73
|