On the dist., cap, where the wires go in, there is a tab labeled TACH.
first port to the right of the input block where the coil and tach wires go in. looking down clockwise
If the wires are Red,Black,Green,and White I can help you. Im also assuming you have HEI ignition. The red wire will go on the positive battery terminal, make sure you run an in line fuse. The white and black wire are for the light, so you will have to tap in to a dash light. White being positive. The green wire will go on the tach lead also known as negative. The cap has the words TACH and BAT on them. Hook it up to the TACH.
There should be a tach output connection on the side of the box somewhere, you just plug your tach pickup into that. If it doesn't work you'll need a MSD tach adapter. I'm unsure of the part numbers but there are 2 different ones, it depends on what you used to wire in your ignition. If you used the white wire there is one and if you used a magnetic pickup ( green and violet wires ) there is another one....MSD-8920. I have a sunpro tach and I had to go out and buy an adapter to make it work...for about 50 bucks.
Your two hot wires go to the load side of your contractor and the two brown wires go to your capacitor
TWO wires
You do need a switched live to the bat terminal, but not to the tach terminal. The tach terminal is the negative side of the coil, the bat terminal is the positive side of the coil. Normally the tach terminal is for the green wire from the tach.
The tach has a lot of wires coming out the back, here are what the are for: ~The RED wire goes to a power source. ~The BLACK wire goes to ground. ~The BROWN and BLUE wires are for the tach internal bulbs. ~The GREEN wire needs to go to a blue wire that is located under your hood top right corner. The blue wire has a black rubber cap on it.
All of the ones that I have worked on have the tach pickup made into the alternator, believe it or not. There are two different alternators that can go on this engine and they look the same from the outside and use all the same wires. They are delco-remy. I'll get you the part numbers.
Not sure if this will help, but on most cars now, there isn't a "speed cable", there is just wires that go to the sensor on the transaxle (transmission) that goes up to the instrument cluster (speedometer, tach, gaugees, etc...).
Make sure all of the wires on the coil are tight and if they are take it to a speedo shop for tach repair.
They go to the wire connector on the fuel tank, there are also two ground wires going from the saddle to the frame.