Has anybody actually answered these questions?
As to the 2* advance
This means the installed centerline has been advanced, or is to be, or is recommended to be, advanced 2 degrees from straight up; which on a 110 cam would be 108, but on a 114 cam would be 112. The cam manufacture has reason to believe that at 2* advanced, it will run the best for you. If you have the time and energy, you can try other installs,but mostly, they will have bugged it out for you.
As to the overlap.
Overlap is or can be, a distinct cycle added to the 4-stroke cycle of your engine. It is a period of time measured in degrees, wherein can be exploited the movement of air into the engine. This time-period really only responds to tuned headers and a free-flowing exhaust. Log manifolds pretty much kills it.
How it works was taught to me to be like this; a slug of exhaust flows down the individual header pipe and comes to a lower pressure area and slows down.The exhaust valve behind it is still open. Think of this slug of exhaust as a syringe. Plug the tiny needle opening and yank it apart. During the yanking you create a partial vacuum in the tube, and when the rubber part comes out, the pop you hear is air rushing in to fill the void. A similar thing occurs in the header, a partial vacuum is created by the fast-moving exhaust slug, and it is at it's highest just before the exhaust valve closes. This means the chamber is now also in a partial vacuum! If we now open the intake valve, and the carb is wide open, then we can fast-track air into that chamber, literally have it be sucked into it. And if we open the intake a lil sooner we can fast-track it, even faster.
So the overlap cycle is like a supercharger, ramming air into the chamber. I said like. And so the more overlap you have, theoretically the more air will be rammed into the engine. But big-number overlap and street engines are not the best of friends, cuz the degrees have to come from somewhere, and if you steal too many from here and there, pretty soon you have a powerhouse engine, but it has to idle at a very high rpm, just to keep running.
So the question is what kindof numbers can we use in a street engine.
Well, IMO the Mopar 292/292/108 cam is too big for most street SBMs, and that's because it has 76* of overlap. I can tell you that this cam makes a boatload of power, but if you don't build your engine to properly use it,and you don't have a matching chassis for it, you are gonna be a very cranky 273 operator.
And, the stock smog teeners had IIRC 20* advance, ran log manifolds, idled dead smooth, and didn't rum much different with headers, cuz 20* is as good as nothing.
So guess what's in between 20 and 76?... 48* is in between.
48* will idle like a 340 . But what you rarely hear about 340s is that headers really woke them up, to the tune of perhaps 30 hp I have regularly heard. So that is a difference strictly traceable to the 44* overlap of the 340 cam, and how it affects power.
