[Fot] Spitfire race motor 1296, Dual or single valve springs?

[George Harmuth]

I've been wondering what's the best approach. I've always run double
springs as an insurance policy against a broken spring dropping a valve but
I have to say I've never broken a spring. Are there any other advantages to
doubles, enough to offset the mass penalty? Neither engine has a
particularly radical cam, .450 and .470, zero lash, and I don't like to rev
over 7200. I know springs are made of sterner stuff these days, should I
use single springs and if so any suggestions?

thanks
mike

63 Spitfire