So, if the 3-rotor fires every 120 degrees of crank rotation, can I just take an off-the-shelf unit and set it to 6 cylinder mode and be good to go?  Sounds too easy! 

Mark Steitle 

A 3 rotor will give you 3 pulses per rev, so a standard 6 cyl tach will work if you can use the LS-1 coil trigger signal.  I put a scope on the LS-1 coil trigger, and measured 4.04 VPP for the square wave.  So far, no tach I've tried will work with this, but if Todd has one that will work with less than a volt, anything's possible. 

If you're planning to use the tach output, you'll still need a divider. 

BTW, I bought one of the BIG round tachs that I mentioned yesterday.  I'll hook it up tomorrow to see if I can at least verify the Tiny Tach reading.  I'll try to find a place for the new tach in the plane, but I'm running out of velcro to stick any other temporary gauges :-)

Rusty (Large print so John can read it <g>)