How does cam timing affect ignition timing? In a short, two word answer... it doesn't.
I get questions from people asking: "My cam is advanced 4 degrees, where should I set the ignition timing on my engine?" The complete answer is; Wherever your ignition timing is normally set at.
Cam timing is VALVE timing. Ignition timing is SPARK timing. Just because they share the same word of "timing" doesn't mean they have anything to do with either other. Just remember; the distributor moves independently of the cam, so the ignition timing can be set anywhere you want it to be, regardless of where your cam is phased at.
I've heard some guys say that if the cam is advanced 4 degrees it'll make the ignition timing advance 4 degrees as well. Well yeah maybe if you were able to time your engine first and then go back and move the cam forward or back 4 degrees afterwards because the cam drives the distributor, but that's not the way it works. You set the ignition timing long after you've built the engine and degreed the cam, so where the cam is phased at has absolutely ZERO to do with what the outcome will be for the ignition timing. Again, they may both share the same word of "timing", but other than that, they have absolutely nothing to do with each other anymore than a rear main "bearing" has anything to do with a wheel "bearing".
If your engine likes 36 degrees of total timing, then that's where you set the timing at, whether the cam is 2 degrees retarded, 4 degrees advanced, or straight-up, it makes zero difference because neither have anything to do with one-another.
If you want to learn more about this kind of stuff, in much greater detail, be sure to check out our Auto Shop Videos series by clicking HERE. We have one titled "Heads, Porting & Valve Trains" that covers a lot of this kind of stuff and MUCH more. These make great Christmas, Father's Day and Birthday gifts!
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