i would call them for info my buddy ran the voodo valve springs off the sight just got the dual to be conservative i personaly if i go comp cam for example ex274h id go with the comp dual springs. crane on crane. id do the same with this cam keeps things consistent and my 340 has a near 500 lift cam and my motor has mp stock style rocekrs and push rods work great. i always like to port and gasket match
