Trying to figure out if I have a stock cam. Looks like a stock '71 383 4V, stamped HP, with windage tray, and I assume it's the smaller cam shared with the 2V and 350hp 440. Here's what I have so far:
@.050" lift at the lifter
IO 6°BTDC
IC 19°ABDC
205° duration@.050"

EO 55°BTDC
EC 26°BTDC
209° duration@.050"


@.006" lift at the lifter
IO 31°BTDC
IC 50°ABDC
261° duration @.006" lift

EO 81°BBDC
EC 8°ATDC
269° duration@.006" lift

Intake is .274" lift at the lifter X 1.5 = .411" lift at the valve
Exhaust is .267" lift at the lifter X 1.5 = .401 lift at the valve

This gives me a 205°/209°@.050" cam or 261°/269° gross, 113.5 LSA.

Now I get two numbers for ICL. Measuring at .050" before and after max lift, then averaging, I get 96.5°ATDC, and averaging from .050" lift I get 102.5° ATDC. Sloppy chain, so that explains the retarded ICL.

There's wear on the cam, too, so that explains the low lift, but the lifter faces still rock against each other showing crown.

Am I doing this right?