Just throwing this out there, but I found my engine isn't nearly as chattery now that I set the timing correctly. It had been about 1mm away from being set at max. retard the entire time I've had the car, apparently whoever replaced the dizzy didn't bother to set it... or they confused the white mark with the red one.

Not saying you should'nt set the valve lash, but some find that doing that doesn't change the sound much.