My 422 smallblock build
I tried the mgispeedware calculator and all it tells me is exactly what my cam car tells me. I tried putting in 106 as ICL and I can’t see any difference in the percentage numbers. Guess I’m not as smart as the calculator.
Go back and where it asks for Lobe Separation Angle you type in 108 (because that is your LSA according to your cam card) and just below that there is a box to put in the amount advance the card call for, which in your case is the number 4.
Then look very close at the overlap triangle and see how it’s centered around TDC. It’s not. Theoretically if your cam has 4 degrees advance ground into it, when you input 4 into the advance box, the overlap triangle would be centered. Again, it’s not.
Then go back to that box and change the 4 into a 2 and look at the overlap triangle. It’s now centered. That means your cam is ground with 2 degrees advance in it, not 4. You can also input a 0 in that box, and you’ll see the overlap triangle is now to the right of TDC (which is retarded from the LSA).
Godbold said in the HR article when the engine combo is well sorted out, they generally call out for tighter than “normal” LSA numbers, and rather than install the cam advanced, they center the overlap triangle.
The whole article is worth reading. I think it’s the March 2020 issue of Hot Rod magazine.