When the cam is advanced it moves the cam in relation to the crank. If the intake closes at 60° with the cam installed straight up it will close at 56° with the cam advanced 4°. Closing the intake earlier moves the peak power rpm down - ~500 rpm for each 10° is a pretty good rule of thumb.
I read in a Hot Rod article that you can advance or retard you timing checking the #1 cylinder. When you get the max cylinder pressure that is what you want to go with.....I wanted to try it but installed mine straight up.....most cams are ground with some advance as stated above.
The Summit cam you've got is ground with 4° advance (112 LSA/108 ICL).
Excelent point = do your home work. Always degree any cam in first so if you are not satisfied you know for sure where your at before discussing the situation over with the cams mfgr. Blindly changing cam timing without degreeing in & talking it over with it's mfgr is taking nothing more than a shot in the dark. No one wants to take it back apart and put it back at zero where it probably should have been degreed into in the first place.
Nice to play with the cam sprocket but PITA having to drop pan to take timing cover off. Did mine on rebuild and while pretty happy with the 265DEH comp cam in my 400 I just cannot be fecked undoing everything again especially as it does not leak. At the time I spotted a couple of two piece timing covers to make the job easier but budget (and the reality that I really wouldn't be mucking with it that much).
Damn chebbies beat us there in regards to cam replacement and adjustment
I had to change the timing cover gasket on my 302 recently, and I was apprehensive because I had just changed the oil pan gasket a year before. That was a pain because I had to drop the front cross member (87 Mustang), so I was worried about causing a leak when I pulled off the front cover. I loosened oil pan gaskets to allow pulling the cover off over the ridge in the front part of the oil pan. In the process, I did break off the front part of the one-piece Fel-Pro gasket. When I put it back together, I used lots of Permatex Ultra Blue, especially in the corner. It's been a couple months, and so far, no oil leak in that area.