Cam Phasing

jos51700 said
That's not really how it works....

Modern engines, my foot. (other than that, DemonX2 is 100% right).
The key was never designed to carry load, ever.

The sprocket bolt that clamps the cam sprocket to the cam is what makes the spinny-magic happen. The clamp load from sprocket to cam is what locks the two together. I ain't doing the math but there's hundreds of pounds of force holding the cam to the sprocket when the bolt is properly torqued.

The keys are supposed to be weak. If something goes south, the intent is to shear the key and not eat up the nice expensive components (although on a small block Mopar you're likely going to trash the valves if this happens).

The key is an alignment aid only and carries no, I repeat NO load.

Well, as an engineer, I don't like to assume anything "back in the day." I know the physics didn't change but I wasn't there so I hesitate to say for sure what someone was thinking for the design.

We're all familiar with the "3-bolt" cams vs 1-bolt. The 3-bolts were used on the more radical cams. Again, I assume the engineers decided they needed increased clampload for the harmonics associated with the bigger lobes so they went to 3 bolts to get that added clampload/friction.

I'll share this: for the crank damper joint (which also uses a key for location), there are highly complex models/calculations run to come up with a calculated value that has to meet a spec to insure the damper joint will not move. Again, the bolt supplies the clampload and the joint is then held tight by friction.

Some of you may have disassembled a modern engine and found a "gritty" washer between such a joint. We call those "diamond washers" as they are impregnated with diamond dust/chips to enhance friction and thus the integrity of the joint. You engineer things to NOT need them (unnecessary cost) but sometimes field data or a challenging design forces you to add them. FWIW