I need to change my valve springs on my motor.

I have this funny feeling these GX springs did there time and wants to be retired.

I have heard of people making some sort of gadgit to compress the springs while the head is on the sub. I'm looking for pics of this kind of setup please, as I would like to make something like this and change the old timers out for a new set. Just don't want to take the head of at this stage, as it is a good gaskit and everything is working good.

Keeping the valve from falling into the cylinder is no issue, will either use air or dd's soft tubing method.

Any help will be appreciated.