So I plan on installing new GSC valve springs and retainers along with my new GSC cams. I have read that there is a way to remove the springs without pulling the head off. The way i have read to do this is by applying shop air to the spark plug hole to keep the valves closed. I am curious how much psi of air do I use?

 

Try researching the rope method. That way there's no chance to drop a valve in the cylinder.

 

Remove the spark plug for the cylinder your working on set that cylinder to top dead center, use the hose from a leak down tester, and pressurize that cylinder to 100psi using shop air, use the tool in the link to change the spring. You may have to use a punch and a hammer to get the original retainers/locks to "break loose". They get a tiny nit of corrosion and need to be unfrozen before the tool will compress the spring without opening the valve. With the piston at TDC, if a valve drops, it wont fall all the way in. But with the cylinder pressurized, they won't drop unless you hit them.


http://www.euroexportinc.com/mitsubi...ing-compressor

 

Just did mine over the weekend using the rope method and the euroexport tool. Was pretty straight forward!