TR2/3/3A Plug Weld CyL Head

Is this what is meant by having a cracked head plug welded? How reliable is this method? (the orange gunk on the valve heads is grease not rust and wipes right off.)

I could be mistaken, but I believe those are "stitches".
https://www.hotrod.com/articles/mopp-1203-cast-iron-cylinder-head-crack-repair/

That's a very common place for TR2-4 heads to crack. But since there is only water jacket on both sides of the crack, it doesn't seem to hurt anything and the conventional wisdom is to just let it be.

I have no doubt Randall is right but since you brought up the subject, I don't think it is considered ideal but is often done to parts that are hard to find replacements for. I had it done on my Healey 100 head, which have been described as having two stages in their lives, cracked, or about to crack. This was a few years back when machine shops were a little more common. I assume there is a bit of skill or art involved, because my guy and a couple other gearheads said there was only one guy that could do it, and he was a bit of a magician.

He did do it for me, I asked if it would hold, he said he wouldn't do it if it wasn't going to be as good as new, I only kept the car a couple years after but nothing blew up.

Thanks for the input guys.

I just brought my TR4A head to a LBC specialist to have it reworked, and the first thing he noticed was a crack in the same place. He said that I probably could just leave it alone, but planned to fix it using the stitching technique. He said welding was an option, but welding cast iron is often disappointing; I don't doubt it.

As it happened, magnafluxing showed quite a few more cracks, so that head will now see service only as one humongous paperweight. But I have another one that could be OK; we'll see.

There are a number of videos about the repair of cracks in blocks and heads on YouTube. The process is pretty interesting.

I always called it a "pin repair" but stitching sounds good too. Here is a pic of the repair done on the head of my Series Land Rover. It has held up nicely, but I think it may be a function of the shop doing the work. My shop does a lot of high performance work and are known to be good.

leave it

If leaving it does not seem the best option, here is a good discussion, IMO, of repair methods:
https://www.enginebuildermag.com/2015/04/engine-block-and-head-repair/

A more sophisticated way to repair a crack head or block is, flame iron spray welding.

https://www.youtube.com/watch?v=NXqVO6hFEUI

Stitching on my TR4:



I have reason to suspect this may have been done at the factory.

Lock & Stitch is it's name. Reliable when done properly, yours looks good from what I can see.