> My 72 TR6 is running a little rough and has a hesitation when
> accelerating from idle. I was doing my normal tune up for my emission
> testing and things seem to be going from not too bad to worse. I believe
> the vacuum advance is not working properly.
Unless it has been modified, or is a PI model, your 72 TR6 does not have
vacuum advance. What you are looking at is actually the vacuum retard. The
advance was deleted for carbed models in 1969-70.
> When I remove the vacuum
> line from the distributor there isn't much change in the timing.
Then something is not working (since it's vacuum retard). If it was vacuum
advance, then you would expect nothing to happen when you disconnect it at
One possibility is that the engine was warm enough to activate the TVS
(thermal vacuum switch), which disables the retard and thereby increases
idle rpm, when the engine starts to overheat.
> I adjusted the timing to 4 degrees ATDC
That is the correct value _only_ with the vacuum retard connected and
working properly. If the retard is not working for some reason, the correct
timing is the 'static' value, around 10-12 BTDC.
> The distributor cap, rotor and points (checked gap) look ok. The lugs
> inside the distributor cap look as if they are aluminum. Shouldn't these
> be copper?
Aluminum should be OK.