My dad figured this one out while we were rebuilding my Miata's engine. Those little valve spring compressors they sell at the local parts store for $15 won't fit on a lot of overhead-cam engines. The tool they had at NAPA was between $100 and $150, and looked just like a huge C-clamp.
So, my dad got a cheap spark plug socket and cut a window into it with a Dremel tool. We used it to squeeze the valve spring, and we could pull out the keepers with a small telescoping magnet.
When reinstalling the keepers (after lapping the valves), we put grease on the keepers to stick them in place before releasing the tension on the spring. I held the keepers with a tweezer to get them in there.
DrBoost
PowerDork
11/5/13 2:58 p.m.
I've got two of these, 5/8 and 13/16.
Why a park plug socket specifically?
yamaha
PowerDork
11/5/13 3:49 p.m.
In reply to ultraclyde:
Any socket will work......I bet they just got this one cheaper. 
DrBoost
PowerDork
11/5/13 4:10 p.m.
ultraclyde wrote:
Why a park plug socket specifically?
I don't remember if it's because I have 100 of each size laying around or if it had something to do with the particular wall thickness or depth...
Bonus points for setting it up so you can change the springs without removing the head.
Use a couple of right angle brackets to attach a rod to the head that runs parallel to the crank. Make a lever that pivots on said rod and pushes down on your modified spark plug socket. Pressurize the cylinder with a leakdown tester, fill it with rope, set it to TDC, whatever you want to do to hold the valves up.
Now you pull down on your lever and pop out the keepers.
We have a rig like this at FM, I used it to change out some leaky exhaust valve seals on a car and I didn't have to disassemble any further than pulling the valve cover.
ultraclyde wrote:
Why a park plug socket specifically?
Yeah, any socket will work. The spark plug socket is extra long, mostly, and we had plenty of extras.
