MSD Rotor phasing

[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.

[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]

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]

Your crank triger is right next to your Nitrous Oxide bottle (which is probably behind the chair in your office).

[RodKnock]

Originally Posted by patrickt

Your crank triger is right next to your Nitrous Oxide bottle (which is probably behind the chair in your office).

How did you know I was a dentist?

[patrickt]

Originally Posted by RodKnock

How did you know I was a dentist?

Cause you're not smart enough to be a lawyer.

[mrmax]

Who's on first?

[patrickt]

Originally Posted by mrmax

Who's on first?

No one; I just rounded the bases.

[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.

[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.

[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.

[Rick Parker]

This is a Crank Trigger, absolutely dead nuts accurate. It does not provide for any advancing of the ignition timing based upon RPM. It fires at the same instant each time. To change when it fires with relation to crank rotation the "Pickup" is moved in a slot on its mount to a slightly different location around the perimeter of the Trigger Wheel (just a few degrees).


http://www.msdignition.com/info.aspx...=32&taxid2=447

[FatBoy]

I've been plagued with a misfire since first getting the car on the road nearly two years ago and I've just got round to checking the phasing. I was putting it off because it meant butchering a distributor cap. But now, having checked it, I can see that the spark is firing way past the terminal post.
I'm irritated that MSD have apparently assembled the distributor wrongly, but I'm also pleased that I have found the cause of the misfire at long last.
I suppose I now need to order one of their adjustable rotors.
They should really supply these free of charge given that it is needed to rectify their error.

I marked the position of the distributor before pulling it out, but forgot to note the position of the rotor.

[Eljaro]

You can not imagine how many times I removed the Webers and the jets and the MSD box and the cables and the alternator and I do not want to go on.
In the end it was that damn rotor in the MSD distributor not being aligned correctly.
Misses at max advance and at cruising speed for several months until I did the cut-up-the-cap thing and found that the phasing was wrong.
The problem is that when they fit the gear at the factory it can be just a matter of a few degrees wrongly pinned to the shaft and the phasing is off. So they should just supply an adjustable rotor if they can't do it precisely.
The same thing applies when you change the gear. Depending the location you are disturbing the phasing in relation to the reluctor.
I had to replace the iron gear for a steel gear because I have a hyd roller cam and that also has made the phasing to be off. So if you start playing with those things an adjustable rotor is probably a must.

[Gaz64]

I can't see the gear relationship being a problem, it's the relationship between the reluctor wheel (at the trigger point) and the rotor.