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i dont believe thats true. i believe mechanical advance as well as the initial timing will change the orientation pickup /cap terminal to the rotor/reluctor spline

the relationship of the rotor tip and star wheel is fixed to the distrib shaft and is driven by the cam (but the relationship can be adjusted as stated above).

The cap terminal is fixed to the body of the distrib housing and will be moved back and forth as the housing is twisted CW or CCW.

When the housing is twisted CW or CCW, the pickup moved forward or aft of the reluctor. thats how mech timing is adjusted. Move housing so the pickup moved toward the reluctor spline and the coil fires off earlier thereby advancing it. move it away, the timing is retarded.

When the coil fires it sends the pulse down to the rotor to arc out to a plug terminal. it WILL JUMP A GAP here. the question is how much.

as the centrifigal advance kicks in, the rotor and the reluctor move so that the reluctor spline moves towards the pickup thereby advancing it

Now, i would imagine the width of the conductor on the tip of the rotor is such that one corner of it aligns with the front edge of the 1/4 wide contact on the cap and as the engine advances, the rotor contact swings through the terminal contact.

point is, the mech and the vac advance changes the relationship of the reluctor spline to the pickup. since the reluctor spline is tied to the rotor it will move in relation to the housing annd the cap terminal is tied to the housing.

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Ignoring vac advance for a second.

The reluctor passing by the pickup is what triggers the coil to fire. When it does fire you want the rotor lined up with the cap terminal.

Since intial advance (rotating the distributor in the block) shifts the cap and pickup together as one, and centrifugal advance moves the rotor and the reluctor together as one the timing of when these events occur in relation to the crank may change but the rotor will always be in the same position in relation to the cap when the reluctor tooth lines up with the pickup.

The only thing that will change this is when the vacuum advance pulls the pickup around in relation to the cap terminal.

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To simplifiy ( I hope) this further, the rotor and reluctor/ points cam ARE ON THE SAME SHAFT so the mechanical advance has nothing to do with a change in phasing. Neither does changing initial timing.

the only thing that can affect phasing CHANGE is the vacuum advance or problems with the advance plate--loose, misaligned, etc.

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