Local auto parts stores (Kragen, etc.) often rent out valve spring compressors, I think it's $7/day. There are two kinds - one that requires the head to be off, and the kind that works with the head on. Just be sure you get the right kind.

-Boyo

'48 Willys CJ-2A / '55.1 Chevy 3600 / '66 Austin-Healey 3000 / '04 Volvo wagon (parenthood!?)