Revolutionary
A few months ago, I replaced my broken Herald speedometer with a Spitfire Mk3 gauge. The style is similar to a 13/60's, but it goes to 120mph... not that the Herald will! To match it, I've had a Mk3 tachometer converted to electronic operation.
The conversion was done by Lionel Otto Instruments (http://www.ottoinstruments.com.au) near Brisbane, who replaced the cable-driven workings with a VDO mechanism. It originally over-read by a factor of two, but this was adjusted by fiddling with some jumper switches and a fine-tuning potentiometer. I used the Herald's old and nasty (but accurate) tachometer to get a baseline reading.
Another recent modification is to fit a proper factory overdrive switch and cowling. The overdrive used to be switched on and off by a toggle switch in the dashboard - again nasty, but it worked. I've wired in an indicator switch as well. One discovery - if you switch off the overdrive while holding the switch, you can get a significant electric shock!
Repainted case
Looks like new!
Calibrating
The conversion was done by Lionel Otto Instruments (http://www.ottoinstruments.com.au) near Brisbane, who replaced the cable-driven workings with a VDO mechanism. It originally over-read by a factor of two, but this was adjusted by fiddling with some jumper switches and a fine-tuning potentiometer. I used the Herald's old and nasty (but accurate) tachometer to get a baseline reading.
Another recent modification is to fit a proper factory overdrive switch and cowling. The overdrive used to be switched on and off by a toggle switch in the dashboard - again nasty, but it worked. I've wired in an indicator switch as well. One discovery - if you switch off the overdrive while holding the switch, you can get a significant electric shock!
Repainted case
Looks like new!
Calibrating
posted by Nick Moore at 5:43 pm
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