Does anyone have an idea of what to size or type of bolt to use to plug the holes where the air injection tubes go? I am rebuilding my 2.0L motor and do not plan on reinstalling all the emissions equipment.

Don't know the metric size in the head to plug. That was covered here in the last few months. I'm not good at searches. If you re-use the nipple then a 3/8" pipe cap will screw on the end.

.....I don't know the details?but.there is also a copper
plug that is used. that i've seen on heads that were done
on my cars!

One of the air tubes was torn up pretty good when I removed it because it had rusted into place and is not re-usable...otherwise I would get the caps--unless I can find another one, but so far they have been pretty hard to find and/or way to expensive for my taste.

Bring the tube to the hardware store.....it's not a special order bolt.

Rich

Call Engine Builders Supply in Reno. IIRC they are the same plugs 911s use.

The threads are M10x1.00. A bolt of the correct length will work fine. You can get plugs that will go down inside, but I prefer bolts because of the friction of the bolt head will help keep things in place.

ball bearings and caps (American thread works believe it or not)

go to ace hardware with one of the injection plugs and its easy to piece together

Same size as the 2 Liter valve adjust screw. I have inserted them covered with teflon tape, works well unless the threads are screwed up.