Max Cam Lift

[nivvy]

I read magazine articles and some of those guys are running like .680 - .720 lift cams???

Wont the pistons hit the valves?

I want to get another roller cam to get a little more lift when I get my new heads...right now I have .620 lift with 1.6 rockers but how much higher can I go...I wanna get in the .650 - .670 range with the 1.6's?

[Chryco Psycho]

I have heard of lifts well over .800 But you need to have custom pistons with thick enough piston heads to allow to have the valve pockets deepened enough , Also a roller cam can close the valve very quckly as the piston approaches so the pockets May not need to be all that deep depending on the duration 

[Moparal]

Do you know what your heads and intake flow at certain CFM's?  Have they been put on a flow bench or ported? These are one of the first steps in tuning your engine for max HP gains. If you have a 620 lift in there now, you have pockets cut in your pistons, or .100 thou ago you would of bent your valves.

[tactransman]

IMO the more lift you go , the higher maintenance the engine is because you put more stress on the rockers,push rods, cam lobes etc.

[heminut]

You also need to make sure you have enough clearance between your valve guides and valve spring retainers.

[nivvy]

Now that I think of it the guy who built my motor had to borrow one of my pistons before my motor got built, until he got a replacement for his motor and his cam is a solid roller with .690 lift...so I guess I should be ok...

[Chryco Psycho]

as stated more lift doesn`t = more flow unless the heads are up to the task you may just be beating up valvetrain parts for zero gains

[nivvy]

Maybe another way to go might to be intake valve size...like going from 2.19 to 2.25...??

[moper]

I see the 499 reference. What exactly are you looking to do? Why make a change? Is the combo not doing something it should, or are you just addicted and want to go faster ?(my personal favorite is that last one)
What heads do you run now? DO you have any flow specs form the heads when it was built? Most aftermarket heads will take well past .700 valve lift before retainers hit. Piston to valve clearance needs the pockets in teh pistons, but duration and lobe design make a huge difference too. I'd venture to say you could make a change easy to .650+, but really you need to measure it. If the duration of your cam is such that the valves are close to the pistons, adding extra lift may be fatal. That's why we "clay the piston" to verify piston to valve clearance witht he cam in the spot it will be run in.