MSD Rotor phasing

[FatBoy]

I'm with you on that one Gary.

I'll order the adjustable rotor tomorrow and look forward to the engine running as it should.

[Eljaro]

Gaz64, you are right, it is the relation between the reluctor and rotor.
I achieved the correction by loosening the pickup screws and taking up the slack of the two holes towards the advanced direction. If that is not enough you need the adjustable rotor.

[FatBoy]

I did do as you suggested and tried moving the pickup as far as possible in the appropriate direction, but it was nowhere near enough to correct the problem. The spark was way past the post and only got worse as the advance came in.

[FatBoy]

Well, I've fitted the adjustable rotor, set it to the right position and re-timed the ignition and..........no change.

The symptoms are exactly the same as before.

[Eljaro]

I'd say shiiit. I also had misfire symptoms at higher rpm before the distributor thing, and that was the cable going from the MSD box to the distributor. I made myself a shielded one ( a good shielded mains cable will do) and guided it along the firewall and the left engine compartment well away of the alternator. That did away with the most noticeable misfire. The rotor thing did away with the hesitation at cruising speed.

[RET_COP]

I read this late but was interested in the topic. Couldn't you just pull the distributor up and rotate the shaft/rotor counterclockwise or clockwise depending on the pointer location to the post and drop it back in, thus realigning the pointer closer to the post, or would that be too much of a jump either way?
Lou

[Gaz64]

Originally Posted by RET_COP

I read this late but was interested in the topic. Couldn't you just pull the distributor up and rotate the shaft/rotor counterclockwise or clockwise depending on the pointer location to the post and drop it back in, thus realigning the pointer closer to the post, or would that be too much of a jump either way?
Lou

If you reread the problem you'll see it has nothing to do with the distributor fitment.

The phasing issue comes about from the rotor misaligned to the lead posts at the trigger point, hence the relationship between the reluctor and the rotor is wrong, no amount of "turning and/or refitting" the dizzy will fix it.

[priobe]

ok sorry I am coming into this late. I would just like to recap to make sure I understand this correctly ( there was alot of chatter here).

Originally Posted by Tom Kirkham

Well with all the problems with phasing distributors, I thought I would take some pictures on how to make a tool and phase your rotor in your distributor. You will need an old distributor cap and a timing light.

The first step is to modify the distributor cap. The V shaped notch on the top is to check and make sure that the top of the rotor is contacting the terminal inside the cap.


I cut two large windows so I could better see what is going on.


Next I marked the rotor with a Sharpie.


Putting everything back together


In this picture I hooked up the timing light to the post I wanted to illuminate. This picture was taken with the engine running and with the timing light hooked up. Note that the mark is lined up with the post. This is what you want.


Hope this helps.

Now from my understanding you are suppose to check this at idle and normal cruise RPM, along with what ever rpm is set for your full advance.

And the line should be straight with the terminal at all three position of testing?

Now with the motion of advancement, I am guessing you will see the line move but still should be pretty close on the terminal line up. Is this correct?

Is the phasing that far off from MSD that you have to make these adjustments.

If so, I would favor Ejaro modification rather than the MSD adjustable rotor. By adjusting the Adjustable rotor, you will have to perform this excersie everytime you replace your rotor, with Eljaro you can use the fixed rotor without checking.

Am I missing something?

[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

[JAC]

Shouldn't MSD correct the problem?

[Tom Kirkham]

To help clear up the confusion... here is a picture of the distributor with the phasing wrong (I flipped the wires so I could get a photo with the phasing wrong) and the engine running. The black blurry thing in the photo is the timing light. Note: how the black mark does not line up with the terminal (the bulge in the cap).



Hope this helps