Originally Posted by
Glowgeek
Here's a thought. I wonder if the previous owner of that 120 overheated the top half of that intake spring during an attempt to remove the rocker pin, or even the keeper C-clip. One of those little butane torches would make quick work of taking the temper out of the top half of a valve spring. Just a few seconds of misdirected flame is all it would take. Always safer to use a heat gun.
And yes Dave, I'm wondering again,
Yep,
Very possible.
Any tech worth his salt would never bring a torch flame near that spring.
My favorite heat source in close quarters is a soldering iron or gun.
At the shop when rebuilding cylinder heads, we 100% checked seat pressure at installed height. Any springs not within mfg spec were replaced.