Have seen alot of information on this subject in the archives. I dont know the answer but bet i could figure it out if i searched.

 

i know my tach didnt work when i put in my msd 6al box. I ended up plugging a wire into the side of the box, but then again i also have an aftermarket tach (autometer).

 

I do not know your particular hook-up, but I recently installed my msd6 on my 240z (1972) and my tach had the signal coming from the positive side of the coil, when I disconected (as required by the instructions) I lost the signal and hooking it up to the side of the msd tach signal gave the wrong reading. Anyway, I called the MSD tech people (Tel 915- 855-7123) and was told I needed a tach adapter (there are two types be sure you find out which one you need). If you need it , it set me back another $50. the question is was it worth it. It was to me I like that MSD6 smooth idell and less smoke. I think they have them fix that way to get some more $$. What can I say...

72 240Z 2.8L, 5sp, 200R 3.9, and MSD, work in progress..

 

Search, I posted info about bypassing the first internal resistor -inside- the tach and conecting it directly to the tach output on the 6AL (don't use the wire in the harness). Tach should work perfect. Otherwise, buy the tach adapter and figure that out!

 

thanks

 

Yup - tach adapter - read your instructions...............