I would buy a new set of valve springs. Cheap insurance...413_Dart said:Resurrecting an oldie. SO I can run the single springs up until .550" lift? Am getting ready to fire this beast and may be getting a cam swap before I do. Just trying to cover my bases. Thanks in advance.
Sometimes I wish I would've just gone with the .509 and saved a few hundred on machine work.speedymopars said:.509 is the biggest lift you can go on average. Remember you have to allow for about .050 clearance at full lift, so .559 coil bind is really .509 (or so) max safe lift.
I have run the .509 cam on a set of untouched 906 heads with just changing the cam and lifters. In reality we changed the valvesprings out a month later so longterm reliability is unknown.
My buddy tried that on the .528 cam and the heads couldn't take it - coil bind, retainers hitting, etc.