Autometer tach on my MAX

[Paul Novak]

I am installing a 5" Silver monster tach with shift lite on my '99 Max. (Automotive type 10k)   I know that tapping off one of the coils for a tach signal will only give me half of the actual RPM's. So I searched the mailing list archives and found a comment about attaching diodes to the either the front or the rear coils and then attaching the tach wire to both diodes (should block one coil from firing the other?), and since the cyclinders are 180 degrees opposite firing, it should give me a 100% tach signal   Problem is: attaching both diodes to the tach wire gives me 0 RPM. Attaching only one diode at a time will give me 50% RPMs.   I have both diodes pointing away from the coils:   [COIL]----->|--------+----------[TACH]                           |                           | [COIL]----->|--------+   I must be missing something - looks right on paper.   Any suggestions?   Thanks, Paul VMOA #941