APT Adjust

[Paul]

I would like to thread and install a plug into the air horn for the APT on my 17057266 pontiac quadrajet What would be the best way to do this so the APT can be accessed?

[Cliff Ruggles]

Our HP rebuild kits come with a plug for the APT hole in the airhorn.  It must be tapped about 3-4 turns deep with a 3/8-16 tapered tap, so the plug sits flush with the top of the casting.....Cliff