My 73 coupe became increasingly difficult to start after a wash or if left in the rain overnite. Cranks fine, lights, radio ect fine. I listened carefully at the firewall just left of the mastercylinder and I could hear what I thought was a short or loose wire beneath the cowl when the key was turned to the start position. I contorted myself to peek under the dash and check for loose connections ect. Luckily I got the girl fired up and as I was checking the underdash ignition switch wiring on top of the steering column she died and will not restart. How difficult is this switch to replace and how far can I safely lower my steering colum to get to this switch? The wires all seem tight in their connectors.....Still cranks but no run

Here's the procedure for a '68 from a Haynes Repair Manual:

1) Disconnect the battery ground cable.

2) Insert ignition key in the lock.

3) Remove the screws that secire the Corvette cover plate to the top center of the instrument cluster.

4) Remove the ashtray and radio.

5) Turn the ignition key to ACC and then insert a piece of wire or a thin rod into the hole in the face of the lock cylinder. Depress the wire to activate the plunger, at the same time turning the key counterclockwise until the lock cylinder can be withdrawn.

6) Unscrew the ignition switch bezel nut and remove the switch.

7) Using a screwdriver, release the anti-theft locking tangs and unplug the connector.

8) Snap the connector into the new ignition switch and install by reversing the removal operations.

Thanks for the info Gunslinger, but the 73 has a regular column switch( 68  has a dash mounted switch and is different) that interlocks with the ignition switch which is located on top of the steering column underneath the dash over the brake pedal ect. and the only way to get at it is to lower the steering column, but I have heard that lowering the column too far can damage the steering components? Any suggestions/comments appreciated.

here is pic of switch in question http://cgi.ebay.com/ebaymotors/NOS-GM-69-79-CORVETTE-IGNITION-SWITCH-W-TILT-and-T-TEL_W0QQcmdZViewItemQQcategoryZ34205QQitemZ110098271283QQrdZ1#ebayphotohosting

This is the ignition switch itself. If this is what you are replacing, you do not need to lower the column, unless you just want to. This switch is located towards the lower end of the column, near the firewall. There are two screws that hold it to the column, either 1/4", or 5/16". Take the screws out, unplug the connector, lift the switch off, and insert the new one. It is a fairly simple project.
The switch has a indented section in it that fits over the pin/linkage from the key cylinder. Just make sure you get the indent lined up with the pin, and all should be well.

Another thing that could be causing your starting issue is the firewall "pass-thru" connection, at the fuse box. You may want to take the bolt out of the center of it(from the engine side), unplug the connector, and check to see if there is any heat damage, or corrosion in the terminals. It is a common problem.

Your method sounds much easier than the one in the 1969 Chassis Service Manual!!  How do you get at the ignition switch; what trim pieces have to be removed?  The ignition key can't be turned on my 69, which hasn't been started in years.   I'm guessing the switch has corroded to the extent it can't be moved.  Does this sound right to you?

what is the problem if you can turn the ignition with out the key. I put the key in and it makes the left your key in the ignition tone I pull the  key out and tone keeps singing. I have to  shake the igniton