Luckily I picked up a spare tach (same prefix, different suffix on the notation at the bottom of the dial; probably has more to do with the yellow/red markings than a mechanical or electronic change to the unit) from a fellow participant a couple months ago...while out and about leaking oil over the streets of Fall River...the original tach at normal cruise speed suddenly bounced a couple times and went right to red line (and I was only doing 60 in 5th gear and the tempo of the mill did not change. Damn.
So...went home, assumed a partial Lotus position (if you take out the steering wheel, it's a lot easier on the driver side), disconnected the old tach and removed. Will send out for repair/calibration later...installed new old shelf spare (it's good to have spares, right?) tach (which is from an S2, albeit with a lower yellow at 6K vs 6500 on the TC) after burnishing up the connectors, a little penetrox anti-corrosion goop on the cleaned fittings, and reinstalled. Fired up the engine (with my garage handheld tach/dwell meter hooked up to the coil), and calibrated the new old tach to the reading on the dwell meter. Must be lucky, had set the idle by ear when I was syncing the carbs...and the idle was at 1K on the dwell meter...it now reads 1K on the Smiths tach after tweaking the adjustment pot on the back of the tach.
OK, so it's an S2 tach in a TC. lower yellow/red. That's ok. Says I'm idling at 1K agreeing with the dwell meter. I can live with that.
