I'm going to step out on the ledge and say what I'm sure others are thinking....you are in way over your head if you are pulling valve springs with no idea of how to do it. Read some magazines such as car craft or Hot rod specifically to do with rebuilding heads. Also you can't just drop in new springs without checking installed height and seat pressure. If you get it wrong, you will most likely drop a valve and grenade your motor. Good luck!!

Hello Pete, Mark here saying thanks again for the ride at the fun run...... I would also try to hit the top of the retainer with a rubber mallet but not too sharply... Just a medium tap should be enough to break that stickyness..... It works good but don't whack too hard as the keepers can go flying. Using your clamp idea sounds like cheap insurance against the valve dropping. Or you can bring the cylinder you are working on to tdc and if the valve falls it won't go down far enough to drop out of the guide.... But if all the plugs are out the compressed air might push the piston back down and rotate the engine slightly.....

I agree with VI Outlaw. You dont seem to know what you are yourself into. You dont have the right tools. Holding the valve with some type of medical clamp through the exhaust port is not the right way to do this. If you tap the top of the retainer ( the round thing) you may force the valve through the clamp and down the cylinder. Try to find someone who can come down to your boat and help you out.
Again, why are you changing the valve springs?

Mark. It was good to have you on board. Still working on this spring thing. Give me the phone number of the guy we talked at lunch, The "head" mechanic. I think I am pushing the valve down as the spring compress. I have to come up a way to keep the valve up.

Got that darn spring removed. I'm only removing one, might be a "lazy" spring so I wanted checked. I had to make my own tool, from a unistrut. lol. The "standard" store thingie just didn't do it. That's all. Thanks for the input.

BTW.. I hold the stem inside the exhaust port, under the guide. You can actually grab it with a niddle nose, but I have a long clamp that I can adjust so it's just snug and it won't fall down. But the cyl is TDC. JIC. Anyway the spring is removed, valve slides up and down nicely.