Help me make a CA/SOHC KA Tach work on a SR!

[kazuo]

Okay.

So I have a digital gauge cluster. I like my digital speedo. I like my HUD. No analog clusters for daddy.

Anyway, as we all know, CA/SOHC KA tachs do NOT work on a SR20DET. I had a SOHC vehicle. Tach no worky.

They didnt have digital gauge clusters on SR20's in Japan.

I need to get this tach from a CA18DET cluster working in the SR20DET.

I have been told I can run a wire from some place or another to the tach and make it work, OR I can take the circuit board off the back of a SR tach and screw on a CA18 face.

The problem with method one is i dont know what wire(s) to run, or where.

Problem with method two is the analog/digital tachs are different sizes, so im not sure if switching the circuit boards and faces will result in inaccurate tach readings.

Any ideas?

Thanks in advance