Fitting size for 1988 chevy 454 air injector manifold

what is the diameter and thread count of the fittings on the air injector manifold that screws into each of the exhaust pipes on the factory header of a 1988 454CID engine????
I really need some help here. Thank you very much
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How do you plug the holes in exhaust manifold after removing air pump and injectors on chevy
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roger454 wrote:

Standard pipe threaded plugs.
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Thanks, but size is not standard pipe thread, I think it may be metric and it is fine thread. Do you know the actual size????
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roger454 wrote:

No, but it would be trivial to run a NPT tap through it.
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roger454 :

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