ignition switch wiring issue

[vintage_car]

When I did a temp wire up on my truck yesterday to get it to fire up the ign. switch was not doing what it was supposed to do. I'd like to know where the problem is at with this diagram. I bought an ignition switch since my truck didn't have one. From the wiring schematic on the back of the switch the wires seemed correct, but it was obvious it wasn't. With the turn of the key the ignition switch has the ACC position, OFF, Run and Start. On the back of the switch it had Start, ACC, BAT, IGN. So when I would move the key to RUN it would start the car and continue to turn the starter over...not something I want. It should just hit the starter when I move the key to the Start position. So I'm a bit confused as to where the wiring mistake is at, hopefully someone can make heads/tails of this.
To fire up the truck I just took the start wire and held it to the bat post on the switch and once fired up released the start wire. to shut the car off I pulled the IGN wire from the HEI Distributor. That all worked, but I really don't want to do that every time.

[dwcsr]

It sounds like you have your solenoid wire connected into the ignition circuit. Disconnect the solenoid wire on the switch and with a test light turn the key to start and see what terminal lights up. Connect the solenoid wire to that terminal. See what happens. If that doesn't work then disconnect the tach and see what happens. The ignition is somehow feeding the solenoid. The key switch could also be bad, even new ones can be defective.