1970 W-31--Ten years ago my engine builder bought into Mondello’s program of a roller cam, roller lifters, rocker arms, and AutoTec pistons. At the time I agreed to go with their milder cam (#RH-94-95) so I’d have enough vacuum for a bake booster and some low end torque. Well, the low end torque never developed, vacuum bounced between 9 and 11. For a number of other issues we tore the engine back down this month, but not before checking the cam timing. We found the cam to be 4º retarded. Trusting this was the main cause for the poor performance my current engine guy recommends sticking with the cam and just correct the timing.

Now, before all the W-31 purist out there give me heat for messing with a good thing, I’d appreciate some wisdom regarding the spec’s of this cam? I’d like to know if there’s anyone using a roller cam in a W-31 block? Looking at the lifter picture you’ll see the lifter tie-bars facing the outside do the interference with the intake manifold crossover. Choosing a cam is similar to finding a compatible wife; however, changing out a cam tends to be cheaper than getting a divorce…

 

I'm sure someone will always claim there is a better/newer cam grind out there, but what you have is not bad by any means.
Yes, it appears the duration numbers are swapped on the cam card (as you highlighted) based on the open/close events.

Going from 4 deg retarded to maybe up to 4 deg advanced would make a huge difference in low-speed cylinder pressure, torque & idle quality.

I had a similar result once when changing a water pump & thought it's not much more work to throw a new timing chain in while the front is apart.
The results from getting the cam advanced back to where it belonged really surprised me,