OEM exhaust manifold AIR thread size?

[zieg85]

Has anyone removed leaky AIR system and plugged the manifolds?  The thread size isn't standard pipe.  Does anyone know of a source for plugs to delete these?  The application is a 1986 Chevrolet C20 7.4L  Thanks in advance

[VileZambonie]

Should be 1/2"-20 but check first to be sure.

[zieg85]

Should be 1/2"-20 but check first to be sure.

I measured the thread pitch and got 18.  I will have to mic it.  Thanks

[VileZambonie]

Let us know what you find. I have a set here I could dig out to check if it stops raining.

[75gmck25]

Its been a long time since I plugged the AIR inputs on my Ford. 

IIRC, I took off the AIR "manifold", cut each small pipe just above the screw-in fitting, and slipped the fitting off the pipe.  Then I found ball bearings that were the right size and dropped them into each hole in the exhaust manifold.  Then I screwed each fitting back on so the ball bearing sealed off the hole in the fitting.   It was in the days before I discovered JB weld, but I think that would have helped with the sealing process.  YMMV.

Bruce

[JohnnyPopper]

Very clever Bruce!

I did a valve job on a GM V6 only to have one of the center head bolts strip out in the block. 

I found a longer head bolt that would reach into the block about 3/4", so I got the idea to find a nut and get it onto the bottom of the bolt.

Problem was obvious, but I found a way to get the nut down into the block.

I brazed a steel rod to the nut at just the right angle, and dropped it into the galley and BOOM! She grabbed, I torqued, and snipped off the steel rod.

Man was I glad to move that project down the road!