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Titomars · 03-27-2015, 10:36 PM

Most GM AIR injection tubes are fitted to the manifolds with flare nuts which are straight threads not NPT. I always use Allen head set screws. The size I have used is 1/2 X 20 the taper of the set screw tip is close enough to the 45deg flare which lets the set screw seal at the flare not the threads. I also use anti-seize on the threads for removal at a later time.

03-27-2015, 10:36 PM	#11
Titomars Registered User Join Date: Feb 2015 Location: Santa Rosa, Ca. Posts: 539	Re: air injection manifold plugs Most GM AIR injection tubes are fitted to the manifolds with flare nuts which are straight threads not NPT. I always use Allen head set screws. The size I have used is 1/2 X 20 the taper of the set screw tip is close enough to the 45deg flare which lets the set screw seal at the flare not the threads. I also use anti-seize on the threads for removal at a later time. Attached Images __________________ 1977 Chevrolet C/10 Silverado. Step-Side, Factory 454, TH400, 3.73 Posi 12 Bolt. 1975 Chevrolet El Camino. 350, TH400, 3.08 Posi 10 Bolt.