911 Tachometer Upgrade
 

I am putting a new Stack 430 Tachometer in my 82 SC and all seems OK except for the fact that there is not readout on the tach! I was hoping to use the factory harness and not have to run a line back to the low side of the coil, but that seems to be my next step...But before I do, I thought I'd see if anyone had any information...

Here's my quandry. I have connected the tach to the black/vio wire that shows as the tach output from the wiring diagram. In the original configuration there is also a white/red wire that goes to the RPM limiter and it also connects to a "TD" post on the back of the original Tach. When I check the 2 "TD" posts with a meter, it would appear that the two are bridged on the original tach.

Should I try to bridge them with the new set up?

Any information would be a huge help!

Thanks in Advance....

Colin

Hello

There is a connector in the enginbay where you can split the black/violet from the whitewie coming from the CD unit.

I just would make sure the wire is working.
Stick in the old tach and check for signal or use any Dwell angle meter to verify signal.

TD is the connector for the Tach.

This is also where the revlimiter is geting his input signal.

Grüsse

911 Tacho Upgrade
 

OK that's a help!

The tach needs a 5V pulse to read the RPM so I've got to add a 1000ohm resistor and 12V to the black/vio to bump up the voltage.

If the white/red is the input for the Rev limiter, can I bridge the white/red with the up-graded voltage now on the black/vio and still have the rev limiter work?

Again, any help would be great!

Thanks,

Colin

Hello

As far i remeber the TD signal is 6-9V.

Thats early S man playground ;)

Grüsse