[lust4speed]

Somewhere way up above I read something that could confuse you. The cam manufacturer has cut the keyway to give you their desired advance. In a perfect world you would set the timing dot to dot and you would end up at 109°. You don't add the additional 4° since the cam company already did.

Now we are a long ways away from perfection and that is why you need to measure. It might be on the money at 109° or advanced or retarded. They did the grunt labor for you and now you just have to fine tune.

Also, because crank pulley keyways and the scarce offset keys are approximately 2° increments, you might only get close to 109°. Like horseshoes, sometimes close is all you are going to get. Most of us will error slightly to the advance side since as the chain stretches it will slightly retard timing. Not unusual that your choice ends up being something like 108.5° or 111.5° because 2° in the real world usually comes out to almost 3°. Do you choose 2-1/2 degrees advance or only a half degree retarded? Tough call. With a good timing chain I'd probably go the half degree retarded because we only need so much tire smoke and a little better top end might be the correct choice.