Well if you would takes some advice from someone who now I am sure knows way less than you and have the heads set up right in the first place you won't have that problem. Or even better yet don't bother to change the cams. So before you put the Zippers 557 in maybe you should check and see what your stock spring height is set up for. Then maybe you will not have COIL BIND or a VALVE STICKING! Oh but wait you don't know how to R & R the heads and don't want to pay someone to do the job right in the first place!
Now in reality the lifter has a lot more play even if the valve hit the piston. Which by the way will not happen with your stock heads and pistons and your less than 9.0 compression ratio at .557 lift. Now if you ask any engine builder they will tell you to use the stronger of the two. Light weight was mentioned at first like someone thought you would gain any horsepower. Which by the way again YOU WON'T
Let me guess you must be an engineer???
Be Safe
THE DAWG
Nope not an engineer actually I don't even like riding on trains, and let me guess as a child you liked lighting fires right?
Oh yeah zippers may own the red shift technology but they did not develop it.
my stock 103 heads are setup for .575 lift and that doesn't mean that what ever cam I have installed I wouldn't clearance check everything (been their done that)
and to the contradict your thoughts not EVERY engine builder agrees with the stronger is better in the pushrod areana!!!
So let me understand something, you're telling me that if someone like zippers sets up my heads their is 0 (zero) chance of valve failure. Does somebody other than you warranty these?
I'll buy those heads everytime, how much? [smiley=brood.gif]
If someone can build it I'll break it [smiley=oops.gif]