MSD Rotor phasing

[FatBoy]

Originally Posted by priobe

Am I missing something?

Yes.

The firing point doesn't move with the change in advance. The reluctor and rotor arm are fixed relative to each other, so once it is set, it is set for the full range of ignition advance.
If the tolerance within the pickup mounting holes gives you sufficient adjustment, then go with that. If it doesn't, you will more than likely need the adjustable rotor. This is a nicely designed and adjustable unit and should arguably be included as standard with the Pro-Billet dizzy.
The misalignment that necessitates the adjustment is between the rotor mounting and the reluctor and has nothing to do with the cap mounting. Therefore, once the phasing is set, you should be able to swap caps at your leisure without need for further adjustment.

Paul

[priobe]

Originally Posted by FatBoy

Yes.

The firing point doesn't move with the change in advance. The reluctor and rotor arm are fixed relative to each other, so once it is set, it is set for the full range of ignition advance.

Ok school time... Please help

Ok I thought when the the rotor moves (not the motion driven by the camshaft) advances, this is what causes the distributor cap to receive voltage before it is aligned on the terminal.

I am I wrong here.

[/quote]
The misalignment that necessitates the adjustment is between the rotor mounting and the reluctor and has nothing to do with the cap mounting. Therefore, once the phasing is set, you should be able to swap caps at your leisure without need for further adjustment.

Paul[/quote]

Then why are we referencing the to the terminal on the cap.

I'm confused?

[FatBoy]

When the rotor moves with the advance, the reluctor also moves with it. Therefore, once the rotor is setup to align with one of the posts at the same time as the reluctor is aligned to the pickup, it will always be so, regardles of the advance.
I did write in post #43 that the misalignment on my distributor got worse as the advance came in. This was an error on my part as at that point, I didn't realise the reluctor moved with the rotor, so I apologise if this cause some confusion.
Does that help?

[FatBoy]

Originally Posted by priobe

Ok school time... Please help

Then why are we referencing the (rotor?) to the terminal on the cap.

I'm confused?

Hi Priobe,
My statement could be a little ambiguous. Of course the position of the cap is crucial, but the point I was trying to make was that the cap isn't where the error is and therefore, any replacement cap will be okay and not require adjustment of the rotor.
The adjustable rotor is to correct a manufacturing misalignment between the rotor and the reluctor.

[Gaz64]

The point of the check is to ensure the rotor button is aligned with any post at its firing point.

As the advance mechanism operates it moves the reluctor (trigger wheel) AND the rotor forward in timing (ignition advancing) in relation to where the engine is at that point.

The rotor button will still be in the same place with a timing light regardless of the timing, be it 10 BTDC or 35 BTDC etc.

Only changes position on vacuum advance distributors.

[RET_COP]

Im' getting it now, the adjustable rotor separates the rotor movement from the reluctor so alignment can be changed, otherwise moving the rotor also moves the reluctor ( the reluctor being the trigger) and No change occurs.
Lou