I still have a completely broken 1.7L head from about 20 years ago when my original car was wrecked. The head is broken but has been useful over the years for learning stuff on. I originally learned how to pull valves and valve guides on this head.
I spent a few hours playing with the welder to see if I could expand my skill with heads just a bit.
1) How hard is it to pull valve seats?
2) How much welding can I accomplish with only 225 amps max?
3) I bought a VFD for my mill so at some point I'd like to learn to cut the valve seats.
Turns out pulling valve seats really isn't hard at all. Now getting a fresh set back in is likely to be a completely different story.
Click to view attachment
I didn't bother pre-heating the head other than what ever heat was put in by removing the valve seats. Turns out 225A goes pretty far. I was able to build up a cracked valve guide boss and was able to lay in some puddles on the combustion chamber side of the head without too much hassle.
I'll have to try pre-heating and see how that goes but it should help a lot.
on item #3 - that involves re-wiring my mill to install the VFD and making a bracket to hold the VFD on my mill so that project is likely a winter project.
I'm a long way from entertaining doing any real head welding and/or valve seat installs but thought I'd post the entry level learning point.