I have an idea.  Let me ask this.  Imagine a primitive distributor with NO ADVANCE mechanisms whatsoever. No moving breaker plate. No centrifugal wieghts. No vacuum canister. Just a set of stationary points and a stator with a rotor sitting on top of it.

Now lets pretend the rotor is sitting pretty directly under the #1 cap pole while the engines #1 cylinder  at TDC of the compression stroke when the engine is off.  Now if you start the engine and its idling at 800 rpms, shouldn't the rotor still be under the #! cap pole?  After all, there is nothing to change any relationships at all.  The only thing happenning is the camshaft is now spinning the rotor.   And if we then rev it up to 2500 rpms, shouldn't the rotor still be directly under the #1 cap pole?  AGain, no relationships are changing at all since there are no other moving parts except the rotor.

CAn we agree that the rotor should still be under the cap pole?  Regardless of whether the engine is off, idleing at 800 rpms, or running at 2500 rpms???

Yes the engine is probably running like crap at 2500 rpms, but if we can agree on the fact that the rotor should still be under the cap pole then we can move onward to adding spark advance to this idea. 

 

Last edited by MarkinSC (9/22/2014 6:28 PM)

This is a dimensional problem. And it is a problem of which parts you got!   I once had a distributor that had a vacuum advance and I switched it to no vacuum advance. When I needed to raplace the points and all I got the stuff for non vacuum advance. BAD MOVE!!! The parts for the vacuum advance unit had a rotor with extended tip to accomodate the advance the vacuum added. Without the extended tip on the rotor, I had the worst backfire you could imagine. I fought that for quiet a while until I remembered changing over the dist to non vacuum. I replace the rotor with the one for the car with vacuum advance and problem solved. Just a little more info for thei amazing thread. You all might want to go out and get a  crank fire ignition and forget it, that is what I am running. No distributor, just good working ignition. I made one from an old Chrysler ignition module and a mag pick up. I made a trigger wheel for the crank pulley that triggers the mag pick up. The thing works good with great top end, the Chrysler box I am using has a little retard at the high end.

MarkinSC wrote:

I have an idea.  Let me ask this.  Imagine a primitive distributor with NO ADVANCE mechanisms whatsoever. No moving breaker plate. No centrifugal wieghts. No vacuum canister. Just a set of stationary points and a stator with a rotor sitting on top of it.

Now lets pretend the rotor is sitting pretty directly under the #1 cap pole while the engines #1 cylinder  at TDC of the compression stroke when the engine is off.  Now if you start the engine and its idling at 800 rpms, shouldn't the rotor still be under the #! cap pole?

Yes.

MarkinSC wrote:

After all, there is nothing to change any relationships at all.  The only thing happenning is the camshaft is now spinning the rotor.   And if we then rev it up to 2500 rpms, shouldn't the rotor still be directly under the #1 cap pole?

Yes.

 

MarkinSC wrote:

CAn we agree that the rotor should still be under the cap pole?  Regardless of whether the engine is off, idleing at 800 rpms, or running at 2500 rpms???

Yes.

MarkinSC wrote:

...if we can agree on the fact that the rotor should still be under the cap pole then we can move onward to adding spark advance to this idea.

This has already been done a few times in the last 1,297 posts.
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Last edited by barnett468 (9/22/2014 8:01 PM)

Greg B wrote:

A cheap HP upgrade is to find a mechanism with a low number, as it equals half of the total mechanical advance

In the newer distributors you will see advance mechanisms with really big numbers.  Those are emmision type advance mechanisms, and can also make your car run like chit.   You want a nice low amount of total advance.  

Actually, this is incorrect. In general, the more advance you have up to the point of excess ie., detonation and/or engine stumbling, the more hp an engine will have.

there is an "ideal" amount of advance per rpm for each engine. the more compression an engine has the less advamce it can run for a given octane of fuel.

also there is an ideal advance that reduces the "bad" emissions. in general, the less advance one has at idle, the lower the emmissions will be.

yes, this can be as complicated as the distributor.

 

Last edited by barnett468 (9/22/2014 9:19 PM)

Barnett post:

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.
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You made this post earlier, and you pointed out that there is a difference between rotating the distributor housing and just moving the plate.   Rotating the plate keeps things relative.  I was hoping to save that tidbit until we got to adding vacuum advance into the mix. 
 

MarkinSC wrote:

Barnett post:

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.
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You made this post earlier, and you pointed out that there is a difference between rotating the distributor housing and just moving the plate.   Rotating the plate keeps things relative.  I was hoping to save that tidbit until we got to adding vacuum advance into the mix. 
 

“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.”
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You made this post earlier, and you pointed out that there is a difference between rotating the distributor housing and just moving the plate.
 
That is correct.
 
 
Rotating the plate keeps things relative.
 
I don’t understand what you are saying. I explained earlier that rotating changes the phasing of the rotor and cap. Or as I said, it changes the point in its rotation where it fires spark to the cap.
 
For a recap from my sore typing finger. The more the pick up or advance plate is advanced, the earlier the rotor will fire in its rotation which means the farther it will be from the cap.
 
Draw a line from the center of the rotor to the center of the cap post.
 
Draw a line from the reluctor tip to the pick up. It can only fire when the reluctor and pick up lines line up.
 
Advance the pick up 20 degrees.
 
The reluctor and pick up are now exactly “20 degrees out of alignment” or “20 degrees out of phase” or “20 degrees apart”.
 
Now, rotate the rotor/reluctr assembly 20 degrees so the reluctor tip lines up with the pick up so it can fire.
 
Look at the rotor and cap post and you will see that they are now “20 degrees out of alignment” or “20 degrees out of phase” or “20 degrees apart”.
 
It’s really quite simple and incredibly easy to understand by actually doing this and the other tests that were suggested.
 


 

Nasty65 wrote:

Red circle = dist cap, black marks represent the terminals.
blue circle = distributor
green arrow = rotor
black asterisk =  8 point reluctor wheel
orange block = mag pickup/points trigger

Rotor and reluctor rotate counter clockwise and are "fixed" to each other, one does not move more or less than the other in degrees of rotation, period. Every 45* of rotation, one reluctor vane lines up with the mag pickup sending a spark across the rotor tip to a cap terminal.

Consider the drawing set at "base" timing (8*, 10*, 14*, whatever....it does not matter for this explanation).  From this point, the dist body and cap are bolted down and cannot move.  In a perfect world, at this point, the pickup, reluctor, rotor tip, and cap terminal are all in perfect alignment.  In the real world, due to things like mass produced parts, worn parts, machining error, etc, the alignment can be "off" slightly.  A couple of degrees isn't much of a problem, but "all" degrees that it is "off" are cumulative.  The vacuum adv moves the pickup in a clockwise direction, advancing the timing, sending the "fire" signal sooner, keeping in mind that to trigger the pickup the reluctor has to be aligned with it,  and the dist and cap are "fixed" and the reluctor and rotor are fixed, so the spark will occur some degrees before the rotor tip and cap terminal are in "perfect" alignment.  Add in any component missalignment and some mechanical advance (could be a little, could be alot depending on how much the advance plate allows and the spring strength on the counter weights) and you could end up with the spark occuring far from the cap terminal.  Electricity follows the path of least resistence, it could be the appropriate terminal, or the one before, or a little to both, or wherever. The effort of "phasing" the distributor, either through an adjustable rotor tip or adjustable pickup, is to get the spark signal firing toward the "lagging" edge of the cap terminal at base timing so that when the "advances" kick in the spark will fall on the "leading" edge of the cap terminal and not off in open space.

Another good diagram and what you said is  correct except for the mechanical advance portion. As I previously mentioned, the mechanical advance has no affect on "phasing" it is physically impossible for it to.

 

hmartin025 wrote:

Hey Barnett, sorry to disagree. When the mechanical advance moves it changes the degrees between the rotor and pickup (or points).
Let all of us keep hashing this out till we all understand....
Howard

hi howard.

more hashing, lol.

it does not change. it is physically impossible for it to. i even posted a photo of the mechanical advance so everyone could see it then i posted a test that one can do to prove what i'm saying.

it is not an opinion or a guess, its simple engineering. i didn't invent the dustributor so don't blame me for how it works, lol.

until someone actually does the test, i see no point for them to say it does not work the way i describe. the test will only take 5 minutes. i have also shown others on an actual distributir how it works.

the rotor and reluctor or points cam do not turn independently from each other. the advance asy is one piece of metal not two. it has the reluctor or points cam which is fixed on it and it has a slot to clock the rotor so it too is fixed on it.

if you grab the assembly and try two rotate the rotor independently if the reluctor or points cam it can not be done.

they would have to move indeoendentky of each other for what you are saying to occur.
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Last edited by barnett468 (9/23/2014 9:56 PM)

OK Barnett, try this: With engine stoped and distributor cap off, move mechanical weights and notice rotor movement! it moves which changes the degrees between rotor and pickup (Points), right! That effects phasing. If phasing is off then that extra movement may be enough to effect engine operation.
Howard
 

Sometimes our brains cannot see whats logical. I know Ive been bitten by that bug MANY times!!!!
I just want us on the same page...
Ive been fooling around these infernal contrary things for over 60 years and still struggle with many concepts. Actually just hardheaded!!
Howard

I think alot of people are getting confused with timing advance and phasing. Mixing the two together and getting a can of worms. We must realize that just because you line the rotor and post on the cap together does not mean that the spark is traveling across the two points when they are touching. This is the phasing part. Without drilling holes in distributor caps or using expensive machinery we can not verify this. Now my example. Imagine a rotor in a position before a cap terminal, It doesn't matter how far just that it is before the terminal and not touching it. This is out of phase. In this example this is where the points or electronic pickup or aliens tell the coil to send a spark from the coil to center cap terminal to rotor to whatever cap terminal is firing. This example can be seen by the guy in the video on page 1 or whatever. The spark jumps to the closest cap terminal which is the next cylinder to fire. All is well at engine idle or low speeds. Now same engine and same rotor phasing. You get into the loud pedal and the ignition advance is going to town. The signal to send the spark across all those points is earlier, because this is ignition advance. This is where you will notice poor drivability or stumbling or maybe just a lack of top end power. Or you may not notice anything at all because its always been that way. You will not know the difference until it is fixed. This is because the spark is sent out earlier and has potentially a larger distance to jump to the cap terminal and cylinder pressures are higher because they are jam packed with fuel and air also making it harder for the spark to jump across the spark plug. More powerful spark the less jumps it makes. You need a more powerful spark the higher RPMs you turn just because resistance is higher inside cylinders. You want it to be accurate in order for it to be good.

The whole idea about verifying phasing is maximising power potential or diagnosing a drivability issue. Once you know the rotor is phased correctly, then you can worry about total ignition advance and rate of advance. Bottom line you want to have the rotor touching the cap terminal when its firing, whether its idling or turning 7k rpms, with no ignition advance all the way to your full ignition advance setting. This is what verifying phasing is about.

Last edited by MachTJ (9/24/2014 7:27 PM)

MachTJ wrote:

I think alot of people are getting confused with timing advance and phasing. Mixing the two together and getting a can of worms. We must realize that just because you line the rotor and post on the cap together does not mean that the spark is traveling across the two points when they are touching. This is the phasing part. Without drilling holes in distributor caps or using expensive machinery we can not verify this. Now my example. Imagine a rotor in a position before a cap terminal, It doesn't matter how far just that it is before the terminal and not touching it. This is out of phase. In this example this is where the points or electronic pickup or aliens tell the coil to send a spark from the coil to center cap terminal to rotor to whatever cap terminal is firing. This example can be seen by the guy in the video on page 1 or whatever. The spark jumps to the closest cap terminal which is the next cylinder to fire. All is well at engine idle or low speeds. Now same engine and same rotor phasing. You get into the loud pedal and the ignition advance is going to town. The signal to send the spark across all those points is earlier, because this is ignition advance. This is where you will notice poor drivability or stumbling or maybe just a lack of top end power. Or you may not notice anything at all because its always been that way. You will not know the difference until it is fixed. This is because the spark is sent out earlier and has potentially a larger distance to jump to the cap terminal and cylinder pressures are higher because they are jam packed with fuel and air also making it harder for the spark to jump across the spark plug. More powerful spark the less jumps it makes. You need a more powerful spark the higher RPMs you turn just because resistance is higher inside cylinders. You want it to be accurate in order for it to be good.

The whole idea about verifying phasing is maximising power potential or diagnosing a drivability issue. Once you know the rotor is phased correctly, then you can worry about total ignition advance and rate of advance. Bottom line you want to have the rotor touching the cap terminal when its firing, whether its idling or turning 7k rpms, with no ignition advance all the way to your full ignition advance setting. This is what verifying phasing is about.

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...just because you line the rotor and post on the cap together does not mean that the spark is traveling across the two points when they are touching.
 
This is correct.
 
 
The spark jumps to the closest cap terminal which is the next cylinder to fire.
 
This is the very least it will do. 
 
 
More powerful spark the less jumps it makes.
 
If the rotor is far enough out of “phase” and/or the ignition has enough voltage, the spark can jump to two poles at the same time even though they are different distances apart which can be seen in the Mallory vid on pg one.
 
 
All is well at engine idle or low speeds. Now same engine and same rotor phasing. You get into the loud pedal and the ignition advance is going to town. The signal to send the spark across all those points is earlier,

This is incorrect. The mechanical advance portion does not spark sooner in its rotation. It is physically impossible for it to do so and this is what some don’t understand.
 

The whole idea about verifying phasing is maximising power potential or diagnosing a drivability issue.
 
That’s one way to say it or one of the purposes.
 
 
Once you know the rotor is phased correctly, then you can worry about total ignition advance and rate of advance.
 
Well it is good to know what the phasing of the rotor to cap pole is, however, not everyone wants to check this.
 
 
Without drilling holes in distributor caps or using expensive machinery we can not verify this.
 
 It can be done without a timing lite but the more a timing chain is stretched the more inaccurate it will be.
 
 
Bottom line you want to have the rotor touching the cap terminal when its firing,
 
It doesn’t actually touch the cap but yes it should be lined up with it and this was explained by the Mallory video and at least 3 other here including myself in the previous posts.
 
 
 

Last edited by barnett468 (9/24/2014 8:29 PM)

.
"So, I always had a simple picture in my head. The spark always fires when the rotor is under the contact"

It is best if it does but it does not always do that if the "phasing" of the rotir to the cap posts is incorrect.


"Timing changes when it fires in relation to the position of the piston."

yes whether it is static, or advanced by the vacuum or mechanical advance.

 
"Advance (mechanical or vacuum) and rotating the distributor body accomplish the same thing."

yes


"Phasing is not a thing."

que, no comprendo?


"Maybe I'm wrong but that`s how I always understood it."

Well you got two out if three and one unknown, lol.
.

 

Last edited by barnett468 (9/24/2014 8:25 PM)