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?

if you're looking for numbers on a stock magnum cam you're unlikely to get it from mopar. if you can find the early '68 road runner advertisements they'll state 276/292 for cam duration seat timing. if you look at modern numbers they state 268/284. the stock cam has long closing ramps and the 268/284 doesn't include all the closing ramp. the 276/292 number does include ramps down to, or very close to .006" lift. i went thru this before and being an old school cam degreeing person stuff got real confusing trying to pin down a number with an asymmetrical lobe. as near as i could tell the 268/284 number is .006" lift on the opening side and .009" lift on the closing side. it gets even more confusing when trying to pick out a stock replacement cam from the second tier grinders who include all the ramp on their seat timing specs. the cam you have might be the 256/260 cam that was commonly used in non-magnum engines. the only problem with that is the lift numbers don't jive.

Asymmetric lobes explains why I got two ICL numbers. Thanks. The cam timing is published in the FSM, but there's no lift number given that they're basing them on.

i double checked myself with a FSM before i gave a reply. the events in the service manual don't give a complete timing event. the closing ramps are so long that the last 5-10 degrees of duration occur within a few thousandths of an inch. i know when i tried to map out a stock magnum cam i was confused until i just kept playing with it. i got into the same situation trying to map out an engle solid i use that has long closing ramps. i understand it better now.