3.5.1 - DIY Valve Spring Compressor ( Paul Saltwick/Andrew Waugh,  February 11, 2005 )

From Paul Saltwick, Feb. 11,2005

The JEC will sell you one for +$200. I made up something similar
with a seal puller handle and a threaded block, but I prefer to
use a C Clamp type with a home made adapter when the head is on the
bench.  The adapter is a 3/4'' pipe nipple with the thread cut
off (1''OD X 1.75'') with a window cut in the side to get at the
keepers. It is wrapped in plastic tape to avoid scratching the tappet
guide.

From Andrew Waugh, Feb. 12, 2005

If you take 3 hockey pucks and cut them along the
diameter, and screw them at the cyl. spacing onto a board
you'll have about the best tool for holding the head. 
    Years ago my dad made, as well as the board, a spring
compressor out of a bit of ''T'' angle to bolt to the head, a
cranked handle pivoted to the ''T'' and the compression bit
was a 1'' waterpipe fitting with a slot cut in it (to get at
the keepers) and an extension bar welded to the top of the
pipe to reach the handle.