On a Honda or Acura? I don't think it matters... I could be wrong. When I installed mine even the guys at the store said to look at how the grooves in the cam are sitting and match it with the pins( or whatever they are called) on the distributor. Thats what i did and it runs good. I do know that you have to get the distributor TIMED after you install it, or you won't have as much power, or you won't pass smog... So just get it timed after its installed...