Ok engine works fine but as soon as I turn the key the engine turns over and when I go all the way as if to start it stops .I changed the starter solenoid same thing.I had taken pictures of the starter set up before I took the engine apart and it is wired the same way.I know some after market solenoids are reversed so I tried that.Same thing.I did attach my tach to the sterring colum could I have gone through a wire and screw something up.The only other thing different is my shifter but I don't see what that could do the back up and Park neutral switches all work.
I recall a similar problem years ago which turned out to be a bad ballast resistor. The problem cropped up without any apparent symptom. Might be something to check.
Hope this helps.
It is usually mounted next to the starter solenoid near the battery. My '73 has an electronic resistor that is labeled as such. I am not sure if the '72 has the same as on some vehicles, it is not electronic.
The resistor's job is to limit voltage to the coil. You get 12 volts while cranking and the resistor drops it to lower voltage once it goes to start/run.
You can use a meter to check. Hook it to the primary side of the coil and have someone crank the car. It should show 12 volts while cranking and if it still shows 12 volts when it goes to the run position, it is most probably the ballast resistor that is at fault.
If that is the case, you can get the resistor from any of the parts stores (Autozone, NAPA, Advance, etc.). They are not that expensive.
Hope this helps.
Remove the tach and see if it will work. I take that you mounted it to the column.You might have nicked or broked a wire.
Do you think it's the cylinder lock ? It's not to hard to replace.