Tried to remove cover plug by drilling 5/64 hole 1/8 deep in plug and turned in #8 self tapping screw and tried to pry out plug with screwdriver as shown in 84 Olds manual. The screw puled out taking 3 threads of aluminum with it. The plug did not move. Tried running screw in farther till it hit adjusting screw, again just pulled more threads without moving the plug. Tried to drill out the plug to clear 3/32 hex wrench hit the adjusting screw destroying the hex socket in it. How can I get the adjusting screw out?

 

I ruined my original carburetor's air horn trying to do just this!

For all intensive purposes, I'd just stick with the factory set adjustment of the TPS. The other plugs were easy to drill out..like on the throttle plate and the idle air adjust.

 

I successfully removed the TPS adjusting screw. I found out the screw is a hard steel hex headed screw about 0.100 to 0.112 across the flats. Older ones are the smaller. I made a hollow left hand spot facing cutter of soft steel so it would not damage the screw head. ID #30(.129) and OD filed to .167 inches. I ground the cutting teeth with a Dremel tool. No fancy teeth just some cuts with relief on the back side.I had to resharpen the teeth eight times before it cut through the remains of the aluminum plug. The plug had apparently been driven in so forcefully that it had formed completely around the screw head into the small machining relief under the screw head. When the cutter finally got deep enough to clear the screw head the screw came right out with the cutter. The soft steel bit expanded so it cut the bore where the Plug seats out to about .188 ID. When I get it back together I will apply some silicone in place of the aluminum plug.

 

"Hugh" came up with a "Bright" idea.