820 BBC heads and dual valve springs

[79centurion]

Does anything have to be done to put dual springs in these heads? They only have single springs in them now, and am looking to go bigger on the cam, but want to know if I am limited by single springs. I dont want to have to have the heads machined or anything. Would like to leave them on and just replace springs.
Dan

[SmokinLowriderSS]

You're robably going to see a machinist anyhow, depending on what valve stem seals you currently have on them.
My 353049 heads fit my 3-piece (2 springs plus damper) set just fine, with no room for the umbrella stem seals that had been used. New seals required a trip to the machine shop to have the guides cut to match.
I think that unless the new spring set is huge, they will fit fine on the factory heads.