MSD Rotor phasing

[patrickt]

RodKnock, if your engine is revving nicely, then don't even touch the distributor cap.

[RodKnock]

Originally Posted by patrickt

RodKnock, if your engine is revving nicely, then don't even touch the distributor cap.

To be honest, I don't have a ton of seat time, so I don't know if it's an acute or chronic issue, but yes, there's was some disturbance in the higher rpm on my last run that I took last weekend. Now, I also need to check the rev limiter to see what's the RPM limit too. I may have been bumping against the rev limiter.

[patrickt]

Originally Posted by RodKnock

To be honest, I don't have a ton of seat time, so I don't know if it's an acute or chronic issue, but yes, there's was some disturbance in the higher rpm on my last run that I took last weekend. Now, I also need to check the rev limiter to see what's the RPM limit too. I may have been bumping against the rev limiter.

Less than 5% of Cobra patients respond to a rotor-phasing. I would treat empirically with a basic tune up, after confirming of course that you don't have a simple rev limiter issue.

[scottj]

Originally Posted by RodKnock

Here's a dumb question. How does one know if he or she has a "crank trigger" system? I'm running a 8594 MSD Billet distributor and a MSD Digital 6 ignition, but now I'm curious, and would like to check my rotor phasing and I know that "crank trigger" systems are treated differently according to the MSD instructions.

Here is a picture of a crank trigger installed on an engine. The red anodized unit mounted on the balancer replaces the reluctor in the distributor and the red bracket is for the pick up. The pick up wires run to the 6al. Timing is adjusted by moving the pick up on the bracket. Phasing is adjusted by rotating the distributor.

[RodKnock]

Thanks guys, I'm 99.99% certain that I don't have a crank trigger, and the wires coming from that "black spirally thingee" go somewhere. I'll be in the garage on the weekend to confirm. I was "getting on it' fairly hard, so I may have hit the rev limiter, but I plan to check it out in more detail this weekend.

The photos really help. Gracias.

[Eljaro]

Originally Posted by RodKnock View Post
Here's a dumb question. How does one know if he or she has a "crank trigger" system? I'm running a 8594 MSD Billet distributor and a MSD Digital 6 ignition, but now I'm curious, and would like to check my rotor phasing and I know that "crank trigger" systems are treated differently according to the MSD instructions.

The 8594 Distributor has the trigger system inside, which is the magnetic pickup and the reluctor which give the signal. The cable coming out goes to the MSD box.
The problem here is that MSD is supposed to deliver the distributors with the mag pickup properly aligned so as to produce a spark when the rotor point is perfectly aligned with the corresponding post in the distributor cap.

In my case and probably in some others the rotor point and the post in the cap do not align when the spark jumps and that created some disturbing hesitation at full advance, because as I have seen while checking the problem and the spark, the spark jumps at the leading edge of the rotor point at idle but changes to the trailing edge when rpm rises.
Anyway, the only thing you can do without having to purchase the MSD rotor phasing kit (they make it because some problems with rotor phasing DO ocurr) is to move the magnetic pickup in the opposite direction of the position of the rotor towards the cap post. You have to remove the glue MSD puts between the mag pickup and the distributor housing and you can move the pickup slightly back and forth, which is what I did and solved the problem. Now the point and post aligh perfectly and the hesitation is gone. You can check that also with the timing light, as the timing will get erratic at full advance.
If you have crank trigger the problem is solved just by moving the trigger in relation to the magnet and /or rotating the distributor.

So checking the distributor phasing with a cut up cap is not to be excluded if you have some hesitation problems, which also show up if under your timing light the mark on the crank pulley is not absolute steady at full advance.

[RodKnock]

Originally Posted by Eljaro

The 8594 Distributor has the trigger system inside, which is the magnetic pickup and the reluctor which give the signal. The cable coming out goes to the MSD box.

I'm confused now. So I do have a crank trigger system, but it's not located on the balancer, but inside the distributor? I'm going to have to read again, and then read again, Eljaro's post, since my less-than-technical brain is having a difficult time understanding it.

Assuming I get the time, I'm going to check the rotor phasing and the rev limiter. BTW, Patrick thanks for photo. I do remember the back side of the Digital 6, but your pic makes it crystal clear. Now, I just need to contort myself under the dash to see what it's set at.

There can be a dozen reasons why it did what it did and one of them could the fact that I ran out of gas two weekends ago and the fuel pump may have sucked up something, but that's hard to believe with a relatively new tank and car.

[patrickt]

Originally Posted by RodKnock

I'm confused now. So I do have a crank trigger system, but it's not located on the balancer, but inside the distributor? I'm going to have to read again, and then read again, Eljaro's post, since my less-than-technical brain is having a difficult time understanding it.

NO, NO, NO. You do not have a crank trigger. You have a regular magnetic pickup in the distributor like everyone else. Quit thinking about a crank trigger, you don't have one. Put it out of you mind. It ain't there.

[RodKnock]

Originally Posted by patrickt

NO, NO, NO. You do not have a crank trigger. You have a regular magnetic pickup in the distributor like everyone else. Quit thinking about a crank trigger, you don't have one. Put it out of you mind. It ain't there.

"Am I clear?"

"Yes, crystal clear."

So you're telling me I have a crank trigger system right?

[patrickt]

Originally Posted by RodKnock

I was "getting on it' fairly hard, so I may have hit the rev limiter, but I plan to check it out in more detail this weekend.

I'm just pleased as punch that you're "spreading your wings" in to the mechanical side of your Cobra (that can be as much fun as driving it). Since you have a hydraulic cam, it's possible that your rev limiter was set by the engine installer at a low number, maybe even 5000RPM or so. You can't miss it when you hit the rev limiter in an MSD unit. It's as obvious as the nose on your face -- it's like kidney stone pain or trying to go through a revolving door that is securely locked down. I mean it; it's that obvious. That being said, crawl under the dash and look at the side of your Digital 6 box. You will see two sets of dials. Only one of them will be important to you (I can't imagine you have the blue line enabled for your 2 step limit). Look at the dial on the right and read the little pointers in the middle of the circular clock for both 1000's and 100's and that will tell you your rev limit. Here's a pic from the manual:

[RodKnock]

Why does a high performance car owner want a "crank trigger" system? What are the benefits and tradeoffs?

[patrickt]

Originally Posted by RodKnock

Why does a high performance car owner want a "crank trigger" system? What are the benefits and tradeoffs?

A crank trigger will give you more accurate timing. This generally doesn't matter at hydraulic-cam type RPMs, so there is no benefit over a good distributor (assuming your gears aren't worn and sloppy, which they aren't). At much higher RPMs, though, accuracy is paramount, and that's where a crank trigger will give you the edge. Now quit thinking about a crank trigger; you don't have one, nor do you need one.

[RodKnock]

Originally Posted by patrickt

At much higher RPMs, though, accuracy is paramount, and that's where a crank trigger will give you the edge. Now quit thinking about a crank trigger; you don't have one, nor do you need one.

Well, you know, when I'm driving down streets in my bucolic neighborhood, in the usual 25mph residential zone, with the Cobra in 2nd gear, trying to make as much noise as I possibly can in order to attract as much attention as I possibly can (a polished Kirkham isn't enough) and I'm thinking to myself, with my left elbow firmly resting on the top of the driver's door, "Hey, you know, I do feel the need for more accurate timing. Timing is everything."

Partick, you sound like one my buddies who works on everything cars. You only need to add the part about "Don't believe everything you read and stop reading."

Edit: I left out the swear words.

[scottj]

Originally Posted by RodKnock

Why does a high performance car owner want a "crank trigger" system? What are the benefits and tradeoffs?

Timing is rock steady and very accurate with a crank trigger since it eliminates the timing chain, camshaft, and distributor. I can also run 2 ignitions and switch between them, one off the crank and 1 off the distributor. The one off the crank is for max power and the 1 off the distributor has the timing retarded to take out a bunch of power (not really applicable for the street). Trade off is the expense.

[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.