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#1 tach wire generator wire placement? (pic included)
Posted: Sun Mar 24, 2024 11:34 am
by autoalain
Folks, old style tach, series 1, has no marking on back where + wire goes, does it matter?, I
do not want to screw it up, I will run new wires from generator a/c back to this unit. Thanks. Mike.
p.s. included pic of tach and an old pic of how my restore is going.
#2 Re: tach wire generator wire placement? (pic included)
Posted: Tue Mar 26, 2024 7:54 pm
by cactusman
It's AC...not polarity sensitive...
#3 Re: tach wire generator wire placement? (pic included)
Posted: Tue Mar 26, 2024 9:29 pm
by Heuer
The S1's used a tach generator driven off the rear of the RH camshaft. This outputs 1v per 100rpm and the tachometer responds to the total voltage, so basically a voltmeter. It is entirely independent of the ignition system, unlike the S2 cars. About the only thing you may notice is the rev counter under-reading which is caused by the magnets in the generator weakening with age. No fix other than replacing the generator and the repro items are prone to early failure so look for a good s/h one off a Mk2, Mk10 or E-Type.
#4 Re: tach wire generator wire placement? (pic included)
Posted: Wed Mar 27, 2024 12:04 am
by bitsobrits
There is a fix for under reading AC tachs-and that is to send it off (to Mike Eck in the US-see the US JagLovers Forum) to be modified to use the tach generator signal as a pulse input. The mod is an internal circuit board, and requires a switched +12v wire to be added. Not other wiring mods, so it appears stock. Found my tach was reading about 800 rpm low before having it updated.