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rotor phasing experiment. whats this mean?

Posted By: aarcuda

rotor phasing experiment. whats this mean? - 05/25/09 01:22 AM

i wet to check my rotor phaing. I cut a slot in a cap and aligned the relutcor woth the pickup and then put the cap on. the rotor was dead center on the cap terminal.

So i starteds it up and fired a timing light at it. it was dead on at idle. every now and then i see what looks like a flash of the rotor way to the right. not sure bout that

When i sped it up, the rotor would move to the right of the terminal by about a 1/4" at first then come back to line up with the terminal.

when i let off the gas from revving it, the rotor goes about 3/4" to the right of the terminal as the motor slows down and then quickly returns to dead on the terminal.

Whats loose? 416 small block with stock type distributor
Posted By: RapidRobert

Re: rotor phasing experiment. whats this mean? - 05/25/09 01:44 AM

Quote:


When i sped it up, the rotor would move to the right of the terminal by about a 1/4" at first then come back to line up with the terminal.

when i let off the gas from revving it, the rotor goes about 3/4" to the right of the terminal as the motor slows down and then quickly returns to dead on the terminal.

Whats loose?

(A) any advancing centrifugal(springs) plus vac adv is going to move the rotor more clockwise(SB) (B) when you let off the gas the vac is VERY high for a split second which pulls the rotor way CW then the vac lessens and the eng slows(less adv both of which move the rotor more CCW. (C) nothing loose that's normal. As Andy put it you just want that range of rotor movement around the circumference to be pretty much centered on the dist cap metal terminal or at least not so far off that it misfires under load when your moving which will happen at a shorter distance from the dist terminal than it would in your driveway.
Posted By: AndyF

Re: rotor phasing experiment. whats this mean? - 05/25/09 03:05 AM

Use a Mityvac or some other vacuum source to run the vacuum adavance and you'll see the rotor move away from the post. Vacuum advance is what causes the biggest problem.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 03:11 AM

forgot to say. my vacuum advance is DISCONNECTED- i mean, theres no vacuum line to the can. the can is still screwed on buts theres no vacuum line to it. is the plate moving around in there?

Im seriously considering a new MSD distributor
Posted By: RapidRobert

Re: rotor phasing experiment. whats this mean? - 05/25/09 03:58 AM

Quote:

is the plate moving around in there?

You could pull the reluctor to get to the 3 sided dark colored snap ring piece & then bend the 3 ears a bit to try & tighten things up or w no vac adv you could drill a small hole vertical between the 2 flat plates & with a small bolt/nut pin them together to gain some rigidity. Something looks too loose that you're not comfortable with?
Posted By: Magnum

Re: rotor phasing experiment. whats this mean? - 05/25/09 04:01 AM

If there is no vacuum to the advance mechanism, that plate is not going to move.

Pull the distributor cap off and twist the rotor clockwise and CCW. Not to the point of going into the advance springs but try to feel for slop in the oil pump to dist drive.

How is the timing chain?
Posted By: RapidRobert

Re: rotor phasing experiment. whats this mean? - 05/25/09 12:55 PM

Quote:

Pull the distributor cap off and twist the rotor clockwise and CCW. Not to the point of going into the advance springs but try to feel for slop in the oil pump to dist drive.
How is the timing chain?

I think you nailed it that this is the "movement" that he is seeing at idle, that they both can(& do)make the rotor & therefore the timing marks jump around at idle. I used the collar on the dist shaft & a good chain & marks are rock steady now
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 02:23 PM

Quote:

Quote:

Pull the distributor cap off and twist the rotor clockwise and CCW. Not to the point of going into the advance springs but try to feel for slop in the oil pump to dist drive.
How is the timing chain?

I think you nailed it that this is the "movement" that he is seeing at idle, that they both can(& do)make the rotor & therefore the timing marks jump around at idle. I used the collar on the dist shaft & a good chain & marks are rock steady now

I think that may be it. I did this last night when I first saw the rotor moving and ya, I can move the rotor back and forth quite a bit before getting into the mech advance. I do have a collar on it btw but my distr and oil pump drive are both used- probably got some slop (also two thinks I didn't replace when I built the motor last summer)

I'm going to try and video it. It's unreal
Posted By: Magnum

Re: rotor phasing experiment. whats this mean? - 05/25/09 02:26 PM

If that turns out to be the problem. Either a new HD oil pump drive or an ugly fix it to hammer the dist end and peen it wider.
Posted By: Anonymous

Re: rotor phasing experiment. whats this mean? - 05/25/09 05:02 PM

Quote:

If there is no vacuum to the advance mechanism, that plate is not going to move.

Pull the distributor cap off and twist the rotor clockwise and CCW. Not to the point of going into the advance springs but try to feel for slop in the oil pump to dist drive.

How is the timing chain?



Slop in the dist drive and chain should not affect rotor phase
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 05:05 PM

well, its not as loose as i thought. its is loose a bit but thats not the oil pump drive thats loose. its a little slop up in the rotor, and where the cent weights slide in the slots. I get a bit there too.

but its not enought to make it like Im seeing it.

and since im looking at only the distrib/rotor any slack in the drive, souldnt matter. my plug will fire when the reluctor passes and show me where the rotor is in relation to the terminal.

Since the rotor and reluctor are fixed together (except for a little slop with the rotor mounting), slop in the TC, oe distrib drive would be invisible to me cause im looking at the plug firing.

So why would the rotor move back and forth like that? it seems like quite a bitthe stuff im seeing supposedly shouldnt be happening because i dont have vacuum advance hooked up
Posted By: Anonymous

Re: rotor phasing experiment. whats this mean? - 05/25/09 05:07 PM

Quote:

Quote:

Quote:

Pull the distributor cap off and twist the rotor clockwise and CCW. Not to the point of going into the advance springs but try to feel for slop in the oil pump to dist drive.
How is the timing chain?

I think you nailed it that this is the "movement" that he is seeing at idle, that they both can(& do)make the rotor & therefore the timing marks jump around at idle. I used the collar on the dist shaft & a good chain & marks are rock steady now

I think that may be it. I did this last night when I first saw the rotor moving and ya, I can move the rotor back and forth quite a bit before getting into the mech advance. I do have a collar on it btw but my distr and oil pump drive are both used- probably got some slop (also two thinks I didn't replace when I built the motor last summer)

I'm going to try and video it. It's unreal



IF YOU ARE POINTING the light at your test hole, the movement you see should NOT be caused by the cam drive or intermediate shaft. It should all be in the relationship of the dist, possibly shaft wear, slop (looseness) in the advance plate, slop in the centrifugal mechanism, etc

What you are seeing in the test hole is the time difference between when the points open/ magnetic trigger and the spark happening at the rotor. You should be able to turn the dist. with an electric drill and get the same results.
Posted By: AndyF

Re: rotor phasing experiment. whats this mean? - 05/25/09 05:11 PM

You think you see the rotor moving back and forth but that doesn't mean that it is actually moving. You are using a timing light as a strobe correct?
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 06:08 PM

Quote:

You think you see the rotor moving back and forth but that doesn't mean that it is actually moving. You are using a timing light as a strobe correct?

yes. the timing light fires on the wire coming from the cap terminal I windowed.

Im definitely seeing the rotor move first clockwise (to the left of the terminal) and then shoot over to the right wheni let off but it will center on the terminal at idle and after it settles at higher rpm.

I think my distributor is a pos that is just all wore out.
Posted By: RapidRobert

Re: rotor phasing experiment. whats this mean? - 05/25/09 06:46 PM

The rotor position(seen w the strobe light effect) is going to change constantly as the rpm changes(until you(at higher rpm's) hit the point where the curve is maxed out) & thats normal. I was thinking that the rotor was dancing at idle which would indicate tchain or intermediate shaft slot clearance or less likely dist shaft runout.
Posted By: AndyF

Re: rotor phasing experiment. whats this mean? - 05/25/09 06:55 PM

Try a different timing light and see what happens.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 07:17 PM

Quote:

Try a different timing light and see what happens.

i only have one. a snapon electronic and i trust it.

here a picture of the rotor with the reluctor lined up engine not running.



Attached picture 5251509-IMG_0025.JPG
Posted By: RapidRobert

Re: rotor phasing experiment. whats this mean? - 05/25/09 08:48 PM

Quote:

So i starteds it up and fired a timing light at it. it was dead on at idle. every now and then i see what looks like a flash of the rotor way to the right. not sure bout that

When i sped it up, the rotor would move to the right of the terminal by about a 1/4" at first then come back to line up with the terminal.

when i let off the gas from revving it, the rotor goes about 3/4" to the right of the terminal as the motor slows down and then quickly returns to dead on the terminal.

(1)My light acts like that when I have a poor(light) connection or maybe crossfire (2)"Comes back to line up with the terminal" if this is when you let it go back to idle its normal (3)it is not 3/4" to the right(its less than that) but goes out that far when you let off the gas? So you let off the gas & it advances(more CW)? If so that sounds like the classic increase of adv with vac adv but you dont have vac adv. bottom line is it missing at any point in time & with it dead center at idle it will always be moving more CW & is it moving enough to cause you a problem. I like to extend the rotor tip w solder & have the tip more CCW so the dist terminal is more in the center of it's range of travel. I'm picky I want everything perfect as the chebby/furds guys will not be so meticulous
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/25/09 08:51 PM

im going to buy me an MSD distributor. i have to find one that fits under the six pack air cleaner
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 12:27 PM

Quote:

The rotor position(seen w the strobe light effect) is going to change constantly as the rpm changes(until you(at higher rpm's) hit the point where the curve is maxed out) & thats normal. I was thinking that the rotor was dancing at idle which would indicate tchain or intermediate shaft slot clearance or less likely dist shaft runout.



no, its not dancing at idle (although every once and then it looks like the rotor os at the terminal right before the one Im looking at).

What I am seeing as I rev it up, the strobe is capturing the rotor move to the left of the terminal (reference picture above) for the reving part. If I rev it and hold it at a higher rpm, the rotor moves back to align with the terminal.

When I let go of the throttle and let it drop back to idle, the rotor moves way the heck to the right of the terminal as its decelerating and then re-aligns with the terminal again when its at idle.

Does this sound like what youve seen?

If the rotor and the relector and the puck-up and the cap are all stationary and the only thing i have going on is mechanical advance, the rotor position should ALWAYS be at the same location because I am firing off the spark plug wire and looking at the rotor. rotor being fixed to the reluctor means they always stay together irregardless of accel or decel or mech advance.

Maybe its just an inherent delay in my timing light that cant pick up the changes in the strobe as fast as its changing when i rev it. ya, maybe the timing light is not changing the strobe as fast as the spark is changing so it shows a delay
Posted By: Anonymous

Re: rotor phasing experiment. whats this mean? - 05/26/09 04:19 PM

If you are sure the advance plate is not moving around, it seems to me at least two possibilites are:

A triggering problem in the light--not likely, but not unheard of. Is this a delay light?


Worn/ loose shaft bushings allowing the shaft to move in relation to the pickup. With the Mopar aluminum housings, this used to be a huge problem, and is why I eventually ended up with a Hemi dual point which has a ball top bearing (tach drive)
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 04:51 PM

Quote:

If you are sure the advance plate is not moving around, it seems to me at least two possibilites are:

A triggering problem in the light--not likely, but not unheard of. Is this a delay light?


Worn/ loose shaft bushings allowing the shaft to move in relation to the pickup. With the Mopar aluminum housings, this used to be a huge problem, and is why I eventually ended up with a Hemi dual point which has a ball top bearing (tach drive)



those are the only two i can come up with too. i check the plate to see if it could move easy (the one the pick up mount to) and its pretty tight. doesnt want to move back and forth BUT i can tilt it and that would change the gap and most likely the timing of the spark
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 05:23 PM

At lower speeds you can have bounce especially at idle. This is normally the combination of the chain slop and the mechanical advance bouncing because of it. There is not enough constant rotation at idle on the cam and it can actually want to turn the cam the other direction for a split second during idling. On some cars with big springs and low vaccuum this will happen several times a second at idle. On many cars you will see this happen for a split second as you give it throttle and when it initially maintains an RPM. If you check the timing with the timing light this will coincide with it, and although people will argue this, this is not necessarily a problem unless it is extremely bad and happens at mid to high RPM. It can be impossible to remove this bounce completely and converting to a timing belt with a tensioner can help.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 05:56 PM

Quote:

At lower speeds you can have bounce especially at idle. This is normally the combination of the chain slop and the mechanical advance bouncing because of it. There is not enough constant rotation at idle on the cam and it can actually want to turn the cam the other direction for a split second during idling. On some cars with big springs and low vaccuum this will happen several times a second at idle. On many cars you will see this happen for a split second as you give it throttle and when it initially maintains an RPM. If you check the timing with the timing light this will coincide with it, and although people will argue this, this is not necessarily a problem unless it is extremely bad and happens at mid to high RPM. It can be impossible to remove this bounce completely and converting to a timing belt with a tensioner can help.



but i should NONE that looking at what Im looking at.

the coil fires when the reluctor spline passes by it, send the bolt thru the top of the rotr, out to its tip, over too the cap terminal and out the plug wire. the timing light fires off when the bolt goes out the wire to the plug.

the rotor and reluctor never change relativce to each other. the pick up never changes cause theres no vacuum advance.

I AM seeing the tip of the rotor move ONLY when i rev it quickly and when I let go and it drops back to idle. rotor is only displaced from the terminal during that split second of Revving it, then it moves back to the terminal if I hold it at high rpm or at idle. its only during the quick rev and de-rev that it moves off the terminal
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 06:14 PM

You have mechanical advance right?

Check this with your timing light at the timing mark (at the balancer) it will do something similar.
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 06:49 PM

Try this.
  • Turn engine over until you see the rotor move.
  • mark the balancer at this point.
  • Now turn the balancer the other way until you just see the rotor move the other way. This is ~ how much slop you have to the distributor.
This is 'A' and ideally the amount slop you will see when you first give it gas, release the throttle, and at idle

Now if you have mechanical advance with no vacuum. If you have vacuum advance just remove and plug the hose.
  • check the timing at idle.
  • Check it again at its highest point.
Subtract the two values and you have your mechanical advance. This is 'B'

Worst case scenario the amount of timing bounce you will have is A and B together. This is if you had a weak spring in the distributor. It will never get that bad because the spring will not allow that much bounce.


The amount of slop in 'A' will cause a certain amount of bounce or timing slop. But the amount of 'A' in combination with 'B' will cause a larger amount of bounce.

Either way this slight bounce is nothing to be concerned with because you are just returning to idle or you are just giving it gas, taking the slack out of 'A'. Unless of course you have a supercharged blown funny car running nitro methane, in which case an errant spark can it can potentially blow the supercharger or the head off.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:15 PM

i know i have slop. but the check i am doing wont see that. the light will fire when the reluctor passes- WHENEVER the reluctor passes. The rotor's position inside the cap gets illuminated by the timing light.

and slop in the distributor wont change the relationship of the rotor to the reluctor except for slop in the rotor to shaft or if there was any slop in the reluctor to the shaft (but its tight there).

and the amount of play i have in the rotor to the shaft is miniscule. Im seeing maybe .001-.003" play in the rotor to shaft but I am seeing 1/2" to 5/8" of jump in the position of the rotor when I shine the light on it and rev it
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:20 PM

If you have mechanical advance this is what you are seeing.
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:23 PM

Quote:

i know i have slop. but the check i am doing wont see that. the light will fire when the reluctor passes- WHENEVER the reluctor passes. The rotor's position inside the cap gets illuminated by the timing light.

and slop in the distributor wont change the relationship of the rotor to the reluctor except for slop in the rotor to shaft or if there was any slop in the reluctor to the shaft (but its tight there).



And the rotor in relationship to the reluctor will change when you have mechanical advance. The rotor will advance as rpms increase, but this advance is thru the the use of two weights and two springs.



and the amount of play i have in the rotor to the shaft is miniscule. Im seeing maybe .001-.003" play in the rotor to shaft but I am seeing 1/2" to 5/8" of jump in the position of the rotor when I shine the light on it and rev it



Correct basically there is no way you can see any of this movement with a just a timing light.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:28 PM

Quote:


And the rotor in relationship to the reluctor will change when you have mechanical advance.





i disagree. both the reluctor and the rotor mount solidly to the same shaft. they mount to this (see pic). When one moves, the other moves right with it. As the weights fly out and move the reluctor, the rotor tip changes with it.

Attached picture 5253687-Distradvplate002.jpg
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:29 PM



If the rotor and reluctor is rigid (do not change in relation to each other) no you should not have a change.
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:30 PM

Quote:

Why is there a slot?



the slot is so the reluctor AND rotor and move wrt to cam shaft
Posted By: aarcuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:32 PM

everything I am viewing is from this plate up. i wont see any changes in the timing chain, cam drive, distrib drive.

all i can see is when the spark comes out the wire and where the rotor tip is
Posted By: HealthServices

Re: rotor phasing experiment. whats this mean? - 05/26/09 08:44 PM

You are right I was trying to apply the timing error or delay that you see at the timing mark and balancer to the phasing of the distributor. This would not apply to the distributor phasing itself.
Posted By: 6T6Cuda

Re: rotor phasing experiment. whats this mean? - 05/26/09 09:19 PM

Quote:

Quote:


And the rotor in relationship to the reluctor will change when you have mechanical advance.





i disagree. both the reluctor and the rotor mount solidly to the same shaft. they mount to this (see pic). When one moves, the other moves right with it. As the weights fly out and move the reluctor, the rotor tip changes with it.



I agree, you are correct, phasing is the relationship between the rotor and the reluctor wheel - it has NOTHING to do with anything else...
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