when you can, grab a dist in your hand or lock it in a vise. OR drill the hole in the cap/unhook the can/hookup light/run the RPM up/see what you see/holler back with what you see

Are you saying the pickup is what is moved in relation to the shaft, not the other way?


It will be months before i will be back home.

No, only vac adv moves the magnet (pickup). We are speaking only of mech adv so the magnet for our purposes is fixed (we are capping the can). mech adv twists the reluctor/rotor CW so that the tooth will reach the magnet sooner (mech advance) and when it does the rotor will be at the same clocking (RP) on the cap which does not make sense. I'd wait for someone to post a video. I knew from my work that mech adv did not change RP but I did not know why/how until I put a dist in my hands. its like a magic trick, you'll see when you get there & I would not have been able to grasp it mentally/figure it out WO having the dist in front of me to work with to defend my statement/position.

If you grab a distributor, you cannot turn the rotor and the drive gear or reluctor independently of each other. they are on the same shaft. The rotor appears to move in the timing light/hole-in-the-cap test because the only time you see the rotor is when the light fires(strobe). The light fires at different times because the timing is changing.
Hook up a mighty-vac to the vacuum can and pull, the plate moves the pickup relative to the rotor and reluctor. This is moving the same plate that the mechanical advance moves.
Reluctor phasing is important because the point where it triggers the pickup has to be when the rotor is in-line with the contacts on the cap.
If the rotor is truly changing position, it's because the drive gear is riding up, out of the oil pump as rpm increases.
What am I missing here?

Ok, I got it now too. Using my example of being at a 350* mark it doesn't matter if the engine rotates the rotor/reluctor 10 more degrees or the mechanical advance does it. It will line up at the same exact phase with the cap and pickup. Boy, why was that so hard to understand.

Now, vacuum advance, that's a different story. Need to look into that next.

So, I was wrong, before. But understand it now.

No. The mechanical advance is handled by the shaft. The vacuum advance is added by moving the plate. They are additive.

That's what my understanding has been for decades. Im not seeing any way else the timing can advance.

I totally understand & I could not have grasped it either (in my mind) until I put a dist in front of me, cuz logic says: if the mech adv moves the reluctor and the reluctor and the rotor are locked together (& they definitely are) then how could the mech adv shifting the reluctor so the light fires earlier (advanced) NOT shift the rotor tip at the same time to where it'd be moved further around the cap terminals when the light fires. it is a magic trick! put a dist in a vise or even in your hand and hold it so the magnet and a tooth are at say 12 o'clock dead even & note the shaft rotor notch position which is 9 o'clock on this one in my hand (rotor tip at 3 0'clock but immaterial to this). Keep the magnet (housing) at 12 0'clock & rotate the tooth CCW several degrees CCW (to the left). then hold the housing and lower shaft immobile & grab the upper shaft/reluctor & twist it CW to the right against the springs till the tooth is back lined up with the magnet & lo and behold the rotor tip (RP) is the same (9 o'clock/no change) with the mech adv maxed out. its a hell of a trick. Mr P body are you with us. After all this I could use a steak today!

What ever Trendz comes up with I will abide by... weather
I'm right or wrong.. I should be sending the dist out
today since I have to go to town

Guy "A" is standing next to guy "B".
Guy "B" takes one step back.
Guy "A" is ahead of guy "B" now, but he never moved.
Guy "A" is the upper distributor.
Guy "B" is the engine.
The mechanical advance is the step backward.

I`ve never even checked rotor phasing on my junk but have been thinking about it for beers, I mean years ............time to check it out. Excellent post...........

Trendz has already confirmed my position. If the only reason you were going to send him a dist was so that he could resolve this, if I may suggest you save your time and shipping money. Thumper I have seen some dizzys with way off RP & a common symptom of that is missing at different vac levels when the can shifts the rotor far enough away from the cap terminal(s) to where the required voltage (to jump that gap) is greater than the available voltage & even getting close to that "limit" stresses the coil. there is also the radial distance which adds to the total gap distance. NAPA has a rotor with a longer blade but you can easily make your own (drill out the rivet) & get the radial gap dead on (.015) then get the circumferential distance (phasing) dead on also. reduce lower shaft end play to .005 with speedway shims or use common 1/2" ID washers & deburr the bevel on one side on the ID/OD made when they are stamped when being mfr'd. Add a side oiler like some of the old points ones had & if you ain't running the vac can you can temporarily add a can & pump it up with a mityvac till the phasing is dead on then drill down vertical into the two plates & lock them in that position with a mini bolt/nut with a spacer inbetween the two plates so they do not tilt when you tighten the bolt then remove the can or unhook the lever from the plate & just leave it to cover the side hole in the dist.

I run a locked MSD dizzy does it still apply?

Yes. See the link to youtube I posted earlier.

Well I sent the dist out... so it is what it
is.. Rick you will have it Saturday... you can
keep it

Where is this link you posted... what page
EDIT
In that video it SHOWS it advancing.. that dist
only has mech advance.. and in that vid he said
about 25*

for what it's worth, i'm with Mr P on this one. i saw this just when playing with the distributor by hand. as the mechanical advance comes into play, that changes the position of the reluctor, which moves the position of the rotor, which changes the position of the rotor to the terminal in the cap.

why then is the tip of the rotor so wide? if it didn't change in relation to the cap, it wouldn't need to be anywhere near that wide.

anyway, i'm going to drill a hole in my cap to make sure i got the new reluctor in the right position, so i'll made a video of that, if there isn't one posted here already. i won't get to it until late next week, so we'll see.

I just read the whole thread, and am with RapidRobert (and Trendz starting at page 2). The rotor phasing would only change with vacuum advance. Mechanical advance doesn't change the relationship between the reluctor and the rotor, just the relationship between the engine and the rotor.

I have stated all along that the rotor tip will change
in relationship to the cap based on mech advance.. RR
says that mech advance will not change the location of
the rotor to the cap... that video CLEARLY shows it does

i agree, plain as day in that video.