Tom,
I cannot elaborate much as I cannot remember exactly where the fault was.
When I got my Jensen Healey some years ago the Pertronix Ignitor
(LU-142A/143/144/162A/163/164/166A, one of these types) was already
fitted and the tachometer was erratic and often read double revs.
The tachometer is from around 1974 and the Pertronix is from
before/bought in 10/2004.
The wiring was a bit dodgy and tired and I replaced some bits and pieces
I think the wire from the Pertronix and/or tachometer was connected to
the coil+/resistor junction (this is what I am not sure about), so the
resistance was only 1,5 Ohms, not the required 3 Ohms. I changed it to
the other side of the ballast resistor so the Pertronix and the
tachometer had the resistance of both the ballast resistor and coil, 3
Ohms together. I also disconnected the wire from the starter motor that
shorts the resistor to get a higher voltage on the coil when operating
the starter to compensate for the voltage drop during starting. When
using an electronic ignition however this is not needed.
After this all worked as it should and I did not have any problems since.
Way back in the early 80's I sometimes encountered a similar behavior of
the tachometer on another Jensen Healey. I had a conventional points
distributor on that car. The erratic behavior always disappeared when I
changed/cleaned the points and renewed the capacitor.
Cheers,
Kees Oudesluijs
[demime 1.01d removed an attachment of type text/x-vcard which had a name of
coudesluijs.vcf]
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