Ok, 73 240Z, original style distributor with Pertronix I. MSD box crapped out on me a couple years ago, but I wanted multiple spark again. Picked up a used crane Hi-6s. Got it wired up per Crane instructions, works but the tach reads high at idle (like 2000+ RPM, and when revving higher starts going higher, then drops, then jumps. Never stays at what sounds close to actual RPM. I tried the leftover MSD tach adapter i had (#8910), no dice. Ordered  TachMatch tach adapter and am getting the same result. If I wire either one according to the old Crane tach adapter instructions, the car won't start. Moved the adapter red wire to connect to the green/white, car will fire but won't run. Connected red, green/white, black/white, plus Pertronix red, runs but tach is still wonky. The red on the Pertronix was originally connected to both the green/white and black/white.

I've attached a diagram of how it is hooked up right now. I am out of ideas.....

The Crane Hi-6S is an Inductive box with advanced dwell and Multispark features. You don't really need the Multi-Spark feature on an inductive box. The spark duration is already very long. CDI  boxes are different as the spark duration is so short. But Multi Spark on an inductive box is really just overkill. 

You can turn off the Multi-Spark feature with the rotary switches  Then you should be able to connect the tach wire from the Factory Datsun harness to the coil negative post. Or connect the TM-02 Trigger input to the coil negative terminal. Give that a try and see how it works. 

Do you have a link to the old Crane Tach adapter instructions? That would help us follow along... 

I bought it specifically for the multi spark feature... I hear what you're saying about the spark being really long though, I guess if nothing, that's an improvement.

If I turn the rotary switches to 0 0 (diagnostic mode) then yes multi spark is off and the tach works fine.

I think I've attached the Hi-6s manual (hard to tell, I'm using my phone).

Thanks in advance? :-)

 

9000-6320_.pdf

Edited May 29, 20177 yr by BadDog
Changed file

Update: I tried wiring it according to the old diagram someone made for the MSD 6a with Pertronix on a Z. It worked!

 

Awesome!!! Good detective work. I'm sure that will help others out who may end up with the same issue. 

Just curious. Did end up using the white wire from the Crane adapter Harness hooked up through the Tach Adapter? That seems to be the same hook up as the Pertronix/ MSD diagram???

Edited May 30, 20177 yr by Chickenman

Yes, if you look at the MSD Diagram, the Crane box has the same color wires for the same purposes. So black (-) from Pertronix is the trigger, and the tach adapter Red is spliced into where the Pertronix Black hooks into the Crane White. The other end of the tach adapter gets hooked up to the "lonely" black/white from the tach i.e. NOT the one in the harness that is paired with the Green/White