My mechanic had a professional valve spring compressor that he let me take measurements off of and I just copied the design with materials that I had on hand.
If you use the exact measurements I used, the tool should work fine. If you change any dimensions, then you may want to gather the materials needed, pull the cam and then make the tool - checking your version of the tool on the car as you make it to ensure that it will work properly.
Construction notes:
Material choice:
This tool could be made from a variety of
materials. I used some 3/4" square aluminum stock and some 3/4" flat aluminum bar stock that I had laying around. Pop
rivets were used to attach the various pieces together. Square or
round steel stock would work fine also. Rivets, bolts or welding
could be used to attach the pieces together depending on what you have
available.
Whatever material you choose to use, make sure
it's fairly stout. You'll be putting a bit of force into the
tool to compress the valve spring so you want to use materials that won't
bend or break!
"L"-shaped mounting bracket:
This bracket needs a 5/16" hole drilled
vertically in
the short leg so it will fit over the cam bearing studs. The
horizontal hole for the pivot for the lever arm should be sized to accommodate
whatever you are using for a pivot. A bolt would work fine as a
pivot, I used some clevis pins I had laying around.
The exact measurements of this part aren't
critical, however if you make this bracket a different size it will affect
the length of the foot and the locations of the holes for attaching the
foot to the lever arm.
The
"foot":
As you can see from the pictures, I used two flat
pieces of stock with a small piece of the 3/4" square stock in
between to provide stiffness. The legs need to be around 3/4"
apart so they can press down on the valve spring seat and still leave
enough room for you to reach in between them and remove or install the
valve keepers.
The foot needs to be easily removable. I
used some clevis pins I had, a bolt and nut would also work.
Lever arm:
A length of 14-16 inches will give the leverage
you'll need to compress the valve springs.
There are two holes for attaching the
"foot" to the arm. Two holes are needed so you can mount
the tool on one cam bearing stud and then pivot it left and right to get
to the valves on either side of the cam bearing stud and the valves are
different distances from the cam bearing stud.
The distances from the pivot to each
hole will probably vary depending on the exact dimensions of your
"L" bracket. The best way to get those two holes drilled
in the correct place is to first mount the "L" bracket to a cam
stud. Attach the lever arm to the bracket. Stand the
"foot" vertically on the valve closest to the cam bearing and mark
one hole on the
lever arm. Do the same on the valve farthest from the cam bearing
stud make a mark for another hole.
Using the tool:
Using this tool is
fairly simple. If you are using it on a head that is installed on
the block you will need some way of keeping the valves from dropping into
the head when the spring is removed. I used compressed air via an
adapter that goes into the spark plug hole.
Remove the cam (duh!). Place the tool over
one cam bearing stud. Use one of the cam bearing nuts to secure the
tool onto the stud. Just hand tighten the nut as you'll need to be
able to pivot the tool.
Pivot the tool so it's over a valve.
Install the foot in the hole in the lever arm that is directly over the
valve.
Place the foot on the valve spring seat making
sure it is centered. Press down on the end of the lever arm to
compress the spring. Reach in and remove the valve keepers.
Gently let the lever arm up to release pressure on the spring.