Hello,

I'm slowly going through a '62 Series IIa that was originally a Central American vehicle. Having the cylinder head freshened and a while pressure testing, we found a leak in a large port, approx 1-5/16" in the rear of the head. There was an aluminum threaded plug that was pretty badly corroded and leaking. The threads are badly corroded as well.
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(sorry, the photo keeps flipping upside down, I've tried uploading and flipping the image 180 deg and re-uploading)

What purpose does that plug serve? Asking in order to decide whether to chase the threads and find another plug. And I'm curious to know.

Thank you in advance,
Dan.