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Location:
Montrose, VIC
Registered:
May 2002
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Re: Engine conversion - hooking up tacho?
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Sun, 23 May 2004 03:39
 
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If you can, by all means do use the factory tacho. However, you may find that it doesn't actually want to trigger from the output on the EMS, in which case there's a couple of fairly easy ways around it. Are you using an SR20 with a dizzy, or individual coils? If you have a dizzy/one coil, then do the obvious and connect the tacho straight to the coil - side. If you're using 4 coils however, then you'll need to take the - side of each coil, connect them all together, and use a diode between each one to stop them shorting. If it's running waste spark (2 channel) ignition, you only need to connect the coil on cylinders 1 + 2 in this way. If you need a diagram to show you how to connect it, let me know. Total cost would be under $5 including heatshrink, diodes, wire, etc. If you don't quite understand, I can probably dig you up a simple diagram showing you how to connect it together.
The other way, if you're a little more electronically minded, would be to build a small amplifier to connect to the tacho output of the EMS, and boost the size of the signal. A suitable circuit is published in Silicon Chip, I THINK it's July '99, as a side note to the CD ignition project.
Whatever happens, you don't NEED an aftermarket tacho despite what people will tell you!
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