.
 

MarkinSC wrote:

Shall I wait for the other contestants to agree?

no, I’m confident they will, lol.

MarkinSC wrote:

So lets start with idle. We have a properly phased rotor but a poorly running engine at idle.  So the need arised to advance the spark. So the first spark advance was simply rotating the distributor to advance the spark slightly for idle.  This was initial base timing setting.

ok, good so far.
 
 

MarkinSC wrote:

The points were mounted to a breaker plate, so rotating the distributor was in essence rotating the points.

yes.
 

MarkinSC wrote:

ANy other relationships changed here?

Yes, the cap moved with the distributor housing.
 
 

MarkinSC wrote:

Any other other events happen here at this point?

Yes, the spark fires sooner in relation to the camshaft and piston position.
 
 

MarkinSC wrote:

Has  the rotor gone out of phase at this point?

No, it fires the same distance to the post no matter how much you rotate the housing.
 
 

MarkinSC wrote:

IF so, is it a small tolerable amount?

It is 0 amount, nada, zilch. 
 
 
 

Last edited by barnett468 (9/22/2014 9:33 PM)

Yeah, I was impressed by that too. But,  I'm still trying to fully understand that though.  I think i need a lesson again in distributors.  I'm going to look at the one that is in the 1950 ford tonight and examine how its built.

I would think that if the distributor wasn't inserted in the block correctly, with the rotor not directly where it should be under the cap when stabbing the distributor in the block,  that would throw the rotor out of "phase". The rotor is secured to the spinning shaft inside the distributor. If its off by a tooth or two, then the rotor will not sit directly under the cap terminal when firing. 

I have a duraspark distributor. The rotor phasing does not have to do with the distributor being clocked the correct way in the engine (that is timing), but it has to do with the relationship of the reluctor (star shaped thing under the rotor) and the magnetic pickup. 

My issue probably came about because I had replaced an old vacuum advance module with one that changed the relative position of the pickup module. I thought they were all the same...I guess not. So when the spark is happening, regardless of if I advance or retard the ignition, the rotor was not pointing directly at the terminal. When the vacuum advance moved the pickup, then I would get a cross fire, bad performance, hesitation, etc.

It only cost me a spare cap and a few minutes to drill some holes to check it out. It will stay in my tool box from now on as a diagnostic tool.

BobN

ok thanks for the details. it makes sense now.

what you actually did was relocate the position of the pick up by rotating the advance plate with a different length vac adv can, so technically it might be called pick up clocking or phasing, lol.

it actually had nothing to do with changing the position of the rotor to the reluctor.

 

Last edited by barnett468 (9/16/2014 6:01 PM)

MachTJ wrote:

I'll admit it took me a while to wrap my head around it. It all makes sense now, definately something to keep in the back of my mind to help diagnose driveability problems on distributor cars.

So after you have the holes in the cap, do you just check it out by pointing your timing light at the cap to see the rotor, or did you just see that the spark was wandering around in no mans land?

I used a white paint pen to mark a line down the center of the top strap on the rotor.  Then you aim the timing light straight down the hole.  When your system fires you will plainly see where the rotor is pointed in relation to the plug position, on the cap, that it should be firing at.

Timing should be done at idle rpm's.  That is why you disconnect any vacuum advance lines prior to checking the timing.  When the vacuum advance is activated under normal operation, it causes the system to fire earlier in relation to the position of the piston, but it will always fire in the same position in relation to the cylinder lug on your distributor cap..  The vacuum advance does not affect the phasing.

 

Last edited by boomyal (9/16/2014 6:45 PM)

boomyal wrote:

barnett468 wrote:

......what you actually did was relocate the position of the pick up by rotating the advance plate with a different length vac adv can,.....

Don't worry, you'll get it.  It took a while for me to really grasp this.  Phasing has zero to do with any vacuum advance actions.Rotating the point/ignitor plate is the same as rotating the distributor itself.  See my post above.

hello;

actually he said he had the arm on his vac can was the wrong length. this arm mounts to the advance plate and therefore determines the position/clocking of the pick up to the reluctor. it is independent of the reluctor and rotor.

moving the plate is actually entirely different than rotating the dist housing because the pick up rotates with the housing, therefore, if your pick up is 5 or 10 degrees out of line with all the other items, it will still be 5 or 10 degrees out of line with the dist cap contact no matter how much you rotate the housing and only the position of it relative to the reluctor and rotor will change.

if your pick up is clocked incorrectly, your car will not run properly.

if one draws a diagram of the distributor, reluctor, poick up, and contact on the dist cap, then draws another one with the pick up out of line/time witrth the reluctor, it is easier to understand.
.
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Last edited by barnett468 (9/16/2014 7:39 PM)

A lot of what was said is true, rotor phasing  (in a magnetic pickup dist such as a duraspark or msd for example, in a points dist it would be when the points opened instead of the mag pickup being triggered) is the relationship/alignment of the reluctor wheel & mag pickup with the rotor tip and cap terminal.  Problem arises when the two "sets" don't line up at the same time.  It's effects are mostly evident when "start retards" and/or when igntion systems are used that retard timing "electronicly", i/e the reluctor triggers the mag pickup, but the ign system delays when it actually fires resulting in a misfire or crossfire.  These are mainly seen in race applications where the timing is "locked" and the ign box is setup to retard timing on startup (can result in starter kickback), or when timing is pulled electronically such as when nitrous is used.  Ford recognized the potential of this problem and aleviated some of it's effects by going to the larger dist caps, placing the cap terminals farther apart, reducing the crossfire potential.  There are adj rotors available for aftermarket distributors to address the problem, and there are some methods out there to tweek stock stuff with a little bit of effort.  I've never had much issue with it on a "stock" centrifugal advance type dist, mainly with "locked out" distributors.  Many racers step up to a crank trigger setup to get past phasing issues. 

Several videos out there explaining it. Here's one MSD put out.

https://www.youtube.com/watch?v=aWMlNwGW0tM

Last edited by Nasty65 (9/16/2014 7:43 PM)

barnett468 wrote:

MarkinSC wrote:

I'm having a hard time with this concept.  Help me where i'm going wrong. Something is not jelling.

I have a distributor here in my hand, with points, v8, Ford, vacuum advance.

Turnng the distributor doesn't turn the rotor.  Doesn't that mean that i could possibly turn the distributor to the point where the rotor is no longer underneath the cap pole?  I'm confused on the difference between timing and phasing.
 

ok having a dist vac can with an incorrect length arm is virtually unheard of so i woud say if your car runs bad it is not due to the wrong vac can.

it is a difficult concept to understand but if you draw the diagrams i mentioned it ,may make it esier for you.

the relationship or position of the pick up or points [they do the same thing] is one thing that determines the timing.

the more the vac can advances the plate with the pick up or points on it, the sooner your plug will fire.

in general but not exactly, the more rpm an engine turns, the more ign advance it requires to obtain optimum perf/hp etc..

one should run as much timing as an engine can tolerate. you can advance the timing until you either hear pinging or until it starts to stumble slightly then back it off around 3 - 4 degrees.

incorrect timing, ezpecially too little can cause an engine to run hotter than it would with proper timing.

the more dynamic [not static] compression an engine has, the less timing it can run for a given octane.

the more timing you can run, the more hp, tq and mileage it will get.

remove your dist cap and put a felt tip mark in line with the rotor tip. this will represent a post on the dist cap. now, rotate the housing. you will see that the rotor stays stationary but the position if it relative to the mark has changed.


..

Sorry, but none of that explains timing vs phasing.

markinSC wrote:

Turnng the distributor doesn't turn the rotor.  Doesn't that mean that i could possibly turn the distributor to the point where the rotor is no longer underneath the cap pole?

Yes.

=markinSC]I'm confused on the difference between timing and phasing.
 

markinSC wrote:

Sorry, but none of that explains timing vs phasing.

"phasing" and clocking are different words tor the same term and term "rotor phasing" simply means the position of the rotor only, relative to the terminal on the cap.

as the video shows, you can alter this position with an adjustable rotor, however, this position is pre-determined by the factory and rarely needs to be changed.
.

Last edited by barnett468 (9/16/2014 8:52 PM)

MarkinSC wrote:

BobN wrote:

Thank you to whoever posted a picture last week of the distributor cab with a huge hole cut in it. Over the weekend, I sacraficed a new cap and cut a huge hole in the top so I could see the rotor between three terminals. With the timing light, I could watch the rotor phasing while reving the engine. The dead spot I have been trying to tune out of my engine was actually a misfire since the rotor was out or phase and between two terminals when the spark is happening.

I checked and I have three different vacuum advance modules and the all have different length arms on them. I tried another module and the rotor is not in phase and the car is running better than it ever has.

Thanks again!
BobN
 

Sounds to me just a bad case of getting vacuum advance kicking in  when it shouldn't have been doing so ( at idle) messing with initial base timing. 

actually that is not exacrly it. it is the position of the pick up as i mentioned. if he had no vavuum to the can it would still have incorrect timing at idle.

the incorrect position of the pick up or points can then be compensated for by using an adjustable rotor and positioning it so it is clocked/phased/timed, correctly.relative to the cap.

instead of doing this, he simply bought the correct dist vac can that clocked the pick up in the proper location.
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Last edited by barnett468 (9/16/2014 9:07 PM)

MustangSteve wrote:

Simply said:

Rotating the housing, as you would do in a simple timing change, does not change the relationship of the rotor and the pickup with each other. 

 

MS, I don't understand that.    i can rotate the distributor in the block with the engine off, and the breaker plate will move along with the distributor housing, which moves the points or the pickup depending on what you have but the rotor does not rotate. So it does change the relationship between the points /pickup and the rotor.

If the housing moves, then the cap which is secured to it, must have moved as well, and the brekaer plate which is secured to the housing must have moved as well, the points /pickup which are screwed onto the breaker plate must have moved as well,  but the rotor didn't.

MarkinSC wrote:

if the arm was too short, then it would have been pullng the plate counter clockwise, regardless if any vacuum was present.  

no, actually it would have been pulling it clockwise in a v8 engine. the dist shaft moves counter clockwise, therefore, the plate must rotate clockwise to increase/advance timing.
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http://t1.gstatic.com/images?q=tbn:ANd9GcRkbwDq-r9p-jrUDyZJLy7VWWkoMOsIBYeC--40_cF7j7AozdyHF981RwJ6
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Last edited by barnett468 (9/16/2014 9:28 PM)