I'm just curious if there's some rule of thumb for how big a cam can be before you get dangerous PTV clearance. Anyone pushing ~.600" and ~240 degrees of duration?

 

I'm not sure what the limits are, but I know that a lot of people on here are running the GM847 cam which has .575/.595 lift and 234/242 duration (int/exh).

 

its not the lift that gets you its the duration and valve timing. you can have a lift of 2.00"s if you want to, but it better but it better be a real small duration becuase the lenght of time that it is a that hieght is what will get you. the only thing that limits you on lift is the valve length and spring ability. but if your running a stock cast head anyhting over a .600 lift will not benifit you enough to justify the exrta money for springs and pushrods, and ect.