Civic Tach Info
Old thread, but wanted to add some info for anyone else interested in trying this.
EG tachs (92-95) use a tach signal from the distributor (Ignition Control Module).
For EK tachs, 96-98 also use a signal from the distributor.
99-00 EK tachs use the square wave signal from the ECU.
DC2 Integras might have the same transition period (94-98 for Distributor, 99-01 for 5V square wave)
My Integra tach is from a 96.
I've tested a DC2 Integra and EG tach on a 240 by wiring the Signal to the Negative terminal on the coil. Both worked without issue. (The EG tach needed some adjustment, read a little low).
From what I can tell, the EG and early EK tachometers can handle using the signal off the negative Terminal on the coil, without issue. Not sure about the later EK tachs.
Don't have one to test (and possibly fry).
The Integra tach is too big to fit in the Tach/Clock section of a 84+ 240 cluster.
Unfortunately, it's roughly the same size as the Speedometer.
Might be nice for a custom cluster, like a STACK style.
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Really liked the response and sweep vs the EG tach I ended up installing for a friend's Wagon (Part #: HR 0143-013)
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Though the EG tach worked and looks cool (9k rpm), I'd say use an EK tacho if you don't mind the Blue.
The shape of the Gauge face requires more trimming to fit the 240 cluster vs the OP's EK tach.
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Also, the location of the EG tacho PCB makes it a bit tough to fit. It's mounted off center towards the top of the gauge, so it touches the opening in the top of the Gauge Cluster PCB.
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Required some clearancing with the dremel, as well and trimming the tachometer PCB edges. Still, is a friction fit. But, it does work.
Power and Ground are taken from the pins that used to power the 240 Clock.
Then add a wire to the TA on the Tacho, and run it to the Red/White wire that's not plugged into anything behind the dash (on 86+ 240s).
The 85 Wagon I put this tach in required me to run a wire through the firewall. Pretty easy. The grommet for the throttle cable has plenty of give and the wire is easy to see/pull through when the cluster is removed.
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