Hello I have a brand new set of 243 heads. I got them from an engine builder that removed them from a GMPP crate engine a customer supplied. My question is what valve springs would it have and how much cam could they handle. They are not yellow or blue for sure. Thanks

 

Crane makes a gentle 200/200 @ .050" and .500 lift to work with the stock non LS 6 springs. Just about any camshaft beyond that will require an aftermarket valve spring to cope with the faster lobe speeds....not just the lift.