plugging this port on headers

[KRS1]

Hey guys,
I bought these Flowtech headers and there is a open port on them. I am going to a carbed system so no need for this port. What sensor/probe normally would go in this area? The hole is around 7/8 of a inch in diameter. I cannot seem to find a plug for it. Normally the ports to plug would be the O2 sensors which are already "plugged" on these headers.
I can fit a 7/8 fine thread bolt in these ports and then cut the bolt and weld it. This would create a "plug" but just wondering if there is a neater way to plug these? Perhaps even just using a "dummy sensor" which originally came with these trucks..
Thanks!

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[b454rat]

Does it go thru into the port?? Dunno what that could be. Looks almost like for a heat for air filter on carbed motors

 

[Nad_Yvalhosert]

Secondary Air Injection tubes. The early TBI engines had an air pump and tubing go around the motor, and thread into the #1 & #2 cylinders.
Get the new tubes, with 1-way valves on each, then loop a hose around the intake to connect them together

 

[KRS1]

Thanks! I am going to the u-pic yard tomorrow and I will look for those air injection tubes. This yard had a few 88-94s available. On the 1994 Suburban (I removed the engine brackets on) doesn't appear to have the air injection tubes..I am guessing like 88-92s or so might have them..
Would anyone happen to know what wrench size works to take these off?

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[Supercharged111]

If it's threaded you should be able to just get a plug instead of tying the things together. My 88 had it, but I don't know what thread they are.

 

[arrg]

I don't know if it's the right size for our trucks, but I've plugged these on other GM vehicles of the same era with a M22x1.5 drain plug from the auto parts store.

 

[KRS1]

Thanks again guys,
I see if I can get these locally
https://www.dormanproducts.com/p-1199-090-055.aspx
M22X1.5 drain plug.

 

[dlindsey19]

I think that is the heat riser tube for the air cleaner if you were running a closed element style air cleaner.

 

[KRS1]

I will probably be using a old Edelbrock open style air filter..
https://www.summitracing.com/parts/edl-1208

 

[PlayingWithTBI]

On the 1994 Suburban (I removed the engine brackets on) doesn't appear to have the air injection tubes..I am guessing like 88-92s or so might have them..

Some states like CA (the most restrictive) had A.I.R. required where Federal Emissions didn't require it. IIRC they are M22 X 1.5 but, the seat is tapered so, you may need to use some type of sealant.

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Here you can kinda see the tapered seat.

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