I'm checking the installed center line (ICL) on my 440 that I'm putting a Summitt 6401 cam in (LC '77 440, Holley SD intake, headers). I'm going to set it up with the dial indicator on the lifter and no valve train, but I got to thinking that with the valve train set up it will effect the #'s, I'm just not sure how much. Has anyone ever compared the two?

Your doing it the correct way now All of the cam makers I know of want you to degree the cam off the lifters, not at the retainers due to the rocker arm ratio changing the lift and timing I've done more than one cam both ways,there are definetly differences I now check the intake lobe center at the retainers, if it is where I want it I then check the exhaust at the retainers to make sure the cam is ground on the lobe seperation the cam card says The motor knows what the valves are doing ( I've found more than one cam ground on the wrong lobe seperation angles )
BTW make sure and check the cam timing at .050 lift on both lifters also

I just bought 2 new cams for my 416.. but on the
one I would have to buy new intake rockers.. dont
feel like doing that... they cost more than the cam
but the second one looks better for the long run.. I
can keep the same rockers and be very close to the same
lift with a little less duration... both were ground on
a 110 lsa so the EFI will like it better... I always use
the lifter for checking center line... but then I check
the retainer to see what the final lift is(being a SB you
lose a fair amount)... once I get the other cam I will swap
out my heads and the cam... I have the W-2s on it now but I
will put my W-5s back on... dont know if I will set the center
line at 104 or 106

Thx for the answers guys. I installed it at 106 (dot to dot , it's supposed to be in at 109 but with the tolerances stacking up it came in at 106). I checked the LSA and its at 114 like it's supposed to be. Duration @ .050 and lift checked out as well. Wasn't that hard and went pretty smoothly