so, the latest. i have been doing many other things, (like life…), as well as on the car, but here is the latest.

i disconnected the tach not far from the MSD box, so the wire was still connected at the tach in the dash, and running from there all the way through the engine compartment to where it was disconnected not far from the box.

there was no change in the behavior of the engine, but i noticed that the tach was jumping up to around 1000 rpm as i was driving! i then tried to reach under the dash and disconnect the wire at the tach, and with my fingers inadvertently made a connection between the power to the tach and the input from the MSD box. the tach immediately jumped to 3000 rpm, and from there followed the rpm of the engine, i.e. as i revved the engine, the tach responded to it!

so i'm assuming from this that there is so much RF bouncing around inside that engine compartment that the input wire to the tach is acting like an antenna, picking up the signal and sending it to the tach.

local theories are that the very, very low resistance of the fire core wires are the culprit. i finally have another set of wires, (actually labeled suppression on the wires) that i am going to try. will give an update once that happens.

once i have tried the wires, i only have one other (somewhat involved) option, and that is to relocate the box to the passenger compartment. but if it really is RF, that is the issue, then the wires should show that.

i'm still not very far from just chucking the whole thing and going to a dual point, but i'll see what the new wires do.

stay tuned...