Like the title says, ive seen a bunch of mazda facts about stock port timing and so on, and ive seen posts regarding moving port timing while porting, but how do you determine the port timing to begin with? Is there a rotary degree wheel? Can someone help me out here? Thanks

 

to be honest, i printed one from a website (i think it was tavia.com or something) a few years. it is what it is (free), but it's worked out okay for my uses so far. i had priced a few "real ones" at the time and i think they were $30-40.

 

Preciate it

 

A degree wheel is not engine specific so they work on piston engines or rotaries equally as well. I too have just used one that I found online and then printed. It works fine. The one thing that will get you is that the reference point you line the degree wheel up with is not the same for both intake opening and intake closing. Or exhaust opening and closing for that matter. One is based on TDC of the compression stroke. The other is based on BDC of the compression stroke which isn't simply 180 degrees of eccentric shaft rotation. It sounds confusing but is actually quite simple. You'll see.