Checking Healey Mechanical Tach at idle

[steveg]

Maybe there are some issues with the BJ8 electronic tach, but my unrestored mechanical tach is quite close according to the Sun Engine Analyzer:

Healey steady 1000 rpm

Healey oscillating 600 - 700 rpm

 

[Bob_Spidell]

FWIW, my BJ8's electronic tach is spot-on and steady as a rock. I calibrated it years ago and it hasn't wavered.

 

[steveg]

FWIW, my BJ8's electronic tach is spot-on and steady as a rock. I calibrated it years ago and it hasn't wavered.

If ours are accurate, another previously mentioned was evidently 300 rpm off in the neighborhood of 1000 rpm.

As a "science project", it would be interesting for folks who have access to dwell tachs to compare them to the cars' tachs and see if there's any pattern of them being off by an appreciable amount in the 1000 rpm area.

 

[Bob_Spidell]

If ours are accurate, another previously mentioned was evidently 300 rpm off in the neighborhood of 1000 rpm.

If it's an electronic tach it's likely it can be adjusted to be more accurate. There's a trim pot on the circuit board for adjustment, but you have to drill a hole in the case to get to it. The mechanical tachs are essentially a speedometer without the gearing needed to drive the odometer and trip meters; and the only adjustment I'm aware of is to re-position the indicator needle.