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I just installed a msd ignition system in my '73L consisting of:

Ready to run billet #8350
Tach Adapter #8920
Blaster 2 coil

Got it hooked up and all works great except the tach reads zero. I've checked, double checked and checked again and all seems to be correct using the MSD diagrams. I have checked my wiring diagrams which indicate that the blk/blue wire is the trigger. I've also read on this forum that others have found the light blue and pink as their triggers. Any suggestions or ideas?

Thanks in advance.
Original Post
I have burned up 3 8920"s I have been using the purple wire to feed the tach from the 8920. I have given up... The first one worked for 3 months. the n burned, the 2nd worked for a week, n burned. The 3rd on burned when I hooked it up thriugh a relay direct from battery. MSD told me that low voltage would kill the 8920 that is why I used it to flip the relay and keep the unit away from he load of the tach. BE CAREFUL and use a small fuse on any power connection. Please let me know if you can pull it off...Guessing RPM in 1362..
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