I've popped then 2 ways. One is to just weld and let them shrink as you say, sometimes with an old valve in behind to tap it out if needed. Very easy as you say and seems to leave the hole nice....but I've always seen afraid the hot seat could stretch the whole, not that I've ever seen it happen, so a couple times I either cut a lot of seat way to make it thin then welded or cut 3 or 4 grooves leaving a thin section so I sdon't touch the head and weld across the grooves so I need way less total heat....but I never had any problem doing it the just weld method.....probably what I should do.
I just realized that months ago lent my very VERY old valve spring compressor to a guy at work I talk to at lunch sometimes.....but we've been reorganizing and I've not seen him or his girlfriend (I assume)since before Christmas when the reorgs began. I need to get a new valve spring compressor. The one I had was an old version of this:
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large spring compressorCapture.JPG
and it was kind of a pain in the butt to use on my tiny little valves. So I'm thinking the smaller cheaper design might actually be better...and it looks like free delivery by the 3/17...that's Sunday which depending how much Lana work there is to do this weekend (it spring again! so yard work and yesterday garage doors went on sale so 2 more more doors ordered, that will mean lighting choices finalized and installed before they arrive) is about when I'll want it...done.
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small spring compressorCapture.JPG
I bought one like that and modified it to be the length I needed. i like it a lot. I have the same lever style in the picture too. Don't like it at all.