why do you need an idoit light?.... just shift when the tach stops moving @ 8000 rpm
lol
Remembering electronics from A boy scout merit badge you would need to find out what the voltage and amperage of the lead line when it reaches the desired RPM then build a device to switch the LED on when the requirements are met. A resistor setup would probably to the trick if you tapped the line and used the resistor only to activate a transistor that would allow and alternate power source to power the LED. I am not certian how the tach works electricly so i cant give you any specifics....someone might make one you can splice in....or you might go to a junk yard and pull one from a late 80's s-10 and see how it works...it has to do witht the distributer p/u but i dont know if it is voltage/amperage/pulse driven....good luck
jon
