Rotor phasing?

493 Mike

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Is there an adjustable rotor to fit my MSD RB distributor? I checked the MSD site-nada.
Mike
 

steve340

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From what I read I think they only make them to fit the Pro Billet and race style distributors. I am thinking I may get one.
Do you know the part number of your MSD?
 

Wietse

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Rotor phasing kit 84211, fits the below distributors.
Since you have not mentioned the part number of yours i don't know if it is helpfull.

The Adjustable Rotor is for use with MSD Distributors using the PN 8437, PN 8433, PN 8431, PN 84333 or PN 84313 Caps. The two piece Rotor provides up to 40° (+/- 20°) of adjustment to achieve proper rotor phasing.
MSD 84211 Rotor Phasing Kit for MSD Distributors
 

6PKRTSE

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My distributor is locked out, no mechanical advance. I use an old cap with a hole drilled inside the number 1 location and adjust distributor accordingly and lock down. Then use the MSD 7531 and Grid to pull timing as needed for traction control and on Spray.
 

steve340

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Why do you need one?
I thought I would chime in and answer this. I always check rotor phasing on a performance engine and it is a must if you use electronic timing control like the original poster.
I only use electronic timing control now so I can easily alter the RPM point the ignition starts to advance and how much it advances. No messing around with springs, weights and bushes anymore.
Rotor phasing is pretty simply the position the ignition fires a particular cylinder in relation to that cylinders distributor post position in the cap.
I will assume it is a points distributor.
In a traditional distributor you have a mechanical and a vacuum advance. When the ignition advances mechanically the rotor moves in relation to the points plate and this maintains rotor phasing. When the vacuum advance operates this moves the points plate in relation to the shaft with the rotor attached to, so the rotor phasing is maintained.
When you use a electronic timing advance or delay controlled from the ignition box or ECU it is electronically delaying or advancing when the ignition fires the cylinders. Because of this you can get the rotor being somewhat out of phase with the cap because nothing actually moves in the distributor to maintain rotor phasing.
 

493 Mike

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Thanks for the responses fellas! I came to the conclusion that I had been thinking incorrectly all this time, believing the rotor would be different in a Mopar MSD distributor than a Chevy. The caps and rotors are universal to the design/all the same. Just another brain fart in my old age I guess.
Mike
 

Wietse

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When you use a electronic timing advance or delay controlled from the ignition box or ECU it is electronically delaying or advancing when the ignition fires the cylinders. Because of this you can get the rotor being somewhat out of phase with the cap because nothing actually moves in the distributor to maintain rotor phasing.
Just to get my head around it, if I understand correct there is quite an angle (rotation) that the rotor is before-at-after a cylinder tip where it can transfer the voltage correct?
Meaning, the rotor does not have to be exactly "spot-on" in facing the tip. So this angle is used with a phased rotor to allow the electronic control to alter the timing where it needs it.

believing the rotor would be different in a Mopar MSD distributor than a Chevy. The caps and rotors are universal to the design/all the same. Just another brain fart in my old age I guess.
Don't worry about that, now you said it I also realized I never gave that a thought.
And I am 40, were just too focused on Mopar that we have no time to look at Chevy or Ford parts. :)
 

steve340

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Yes you are quite right - there is some tolerance either way either to the right or left of the post.
You cannot get it totally perfect just close enough that you do not have a misfire, a crossfire in the cap or waste spark energy jumping a super wide gap.
You try and adjust to a point were the rotor "sweeps" past the cap post through the timing curve.
Get the rotor as close to the post as you can and job done.
An engine with a traditional timing curve and somewhere around 14 degrees of advance is not to problematic but a turbo engine with boost retard can cause some issues.
 

Wietse

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Yes you are quite right - there is some tolerance either way either to the right or left of the post.
You cannot get it totally perfect just close enough that you do not have a misfire, a crossfire in the cap or waste spark energy jumping a super wide gap.
You try and adjust to a point were the rotor "sweeps" past the cap post through the timing curve.
So in this time (in crank degrees) the rotor is at/near the post is where an ignition control can control the timing by advancing or retarding the coil to create the spark.
To me it seems that it would not be possible to have a, say 40* advance/retard range in that short period of crank degrees the rotor is at/near the post.
Then again, is that the reason you need to phase the rotor? (like with a Sniper EFI it states to install the dizzy at the 15* BTDC mark)
FAST EFI might have the same or similar number I guess for phasing.
 

steve340

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I don't get too hung up on rotor phasing but I do like to check it during the bed in/tuning phase.
On most engines it would qualify as a small tuning tweak.
However if for some reason it was well out it would cause problems that would be had to find and it is worth checking so you know it is correct or close.
I have never had an MSD be that far out that it caused a problem. I do not mess with turbo or nitrous systems that need to retard timing electronically.
Most engines no matter what they are used for only have say 25 degrees maximum advance from the base timing.
The adjustable rotor is really a great idea.
 
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