I finally got the new engine installed and running... but it quickly developed what sounded just like an exhaust leak, coming from the passenger side of the engine compartment. After looking all over and trying to figure it out, I found that the "freeze plug" on the front of the head had popped out.

Now, I didn't look as closely as I should have while rebuilding it, but I had assumed that plug sealed a water passage. Since no water was coming out of it, I'm assuming it actually seals the air injection passages.

Am I right, or is something horribly wrong? I've been watching the temps and coolant usage, and so far, everything looks good, but I'm a tad concerned.

Edit: Head is from a '78 Volare.

I have never head of a freeze plug on the head. The only holes in the head that are visible from the exterior are the spark plug holes, the holes for the manifold studs, coolant passages, and the AIR injection port. But the AIR injection port is on the manifold side of the head by the firewall.

Where, excatly, is this "freeze plug" hole? Is it threaded for a fitting or is the hole smooth like a normal freeze plug hole? I have never heard of such a hole on the head.

Smooth hole, approx. 5/8" diameter. There's one on the front right underneath the ledge, and one on the back as well.

I have no clue what these might be. Picture?

I'll get pics when I can, but it will probably be a few days. (I'm gettin ready to head home for what's left of my spring break.)