If I can find some springs in a day or so I will run it
for you and video it and post it.. its all about the
relationship to the cap.. why do you think they call it
mech advance... the light is always in sync with the rotor
but not if you put a line on the cap
EDIT
why would the top twist is it wasnt gonna move

the rotor phasing does not change with mech adv/RPM and that (only) was our point of contention. with a functioning mech adv system (slots/weights/springs) with the vac can capped: if the rotor is pointing dead on at the center of a cap terminal at any RPM which is the RP then any amt of RPM/mech adv change will not change the RP (it'll still be dead on) or a bit behind or ahead whichever you started with). this is the hardest ten bucks I've ever earned in my life! (& I ain't collected yet). EDIT P yes make sure your mech springs are functioning & drill the hole in the cap as this is ONLY about if the rotor moves or does not move with the light on it as you rev it & get into the springs (advance)

Your right.. its not worth the added talking
at the moment.. I'll find the stuff.. I'm sure
I still have some dist junk around.. I'll video
the test so all can see... I wonder why they call
it mech advance

i'm with Pbody on this, when you adjust initial you move the dist. housing and the rotor stays in the same spot.
with the mech advance the rotor must move in relation to the dist cap or you can't actually have advance.

not sure why you can see it with the vacuum and not with the mech advance. must have something to do with the pickup coil trigger the timing light...

ps, wish i had an extra dist. here to look at but i gave it to my brother to use and i'm not bothering with pulling one off a vehicle

I remember how we tested this in the lab.. we
set a strobe light up at the same frequency as
the dist was turning in the machine.. it was
rock solid.. then as the rpm went up you could
see the rotor move.. then turn up the strobe
frequency to find that rpm and verify the dist
machine rpm... then we would verify the angle of
advance.. we had to do this on each engine group

Maybe the mech and vac together moves enough so he can see it, but just not with only the mech

A distrubutor machine is neat to use. I was going to snag one, but i finally decided tech was moving away from this stuff fast enough it wasnt worth it. Better to put the money into efi, comp controlled timing.

my head hurts. i'm old. who do i send $10 to ?

ME!!!

KR are you in, ($10 entry fee)!

I have a dist machine, but I have no Chrysler distributors. Send me an old distributor and I will make a video. RapidRobert is right... And I was the first to dispute him.
Anything that happens BEFORE the pickup is irrelevant.

I'm still trying to find at least one somewhat heavier
spring... if I can find something I'll send you a dist
EDIT
since you have a dist machine the light springs will
be fine.. just put a line on the cap for the reference
point.. let me put this back together... send me you
address in a PM

My peep-in cap for checking rotor to cap indexing.

I only have a vent in the ones I run... I found
a dist today and put it together and will ship
it to Rick so he can run it on his dist machine

P body it is time to settle up. Lets do this if you would please, take the dist before you ship it & clamp the lower shaft in your vise with a rag to protect the shaft of course & turn the housing till the magnet is lined up with a tooth and note the rotor position relation to the cap (which is the RP clocking) this is RP with no mech advance. now turn the housing just a bit CW so the tooth is now a bit to the left (CCW) of the magnet & this is/will be the tooth approaching the magnet in normal CW rotation. Now hold the housing rock steady still then twist the rotor CW (which is giving it mech advance) till the tooth is lined up with the magnet (like before) which'll be when it fires which is what you will see/be at with the light and the rotor will be in the same clocked position on the housing/cap terminal as it was before you twisted (advanced) the reluctor/rotor.

Thats the thing.. it will move BUT its not gonna move much..
and as you said.. the light will still show the rotor..
but if you mark the cap and start increasing the rpm..
the mech advance starts to move the rotor... the light
still flashes at the rotor.. but the rotor moved in
relationship to the mark on the cap... like I say.. the
slots in the advance plate only gives about 16* of advance
at the crank... 8* on the dist(or what ever the
advance plate is set up for)

It sounds like we gotta wait till you can put a cap with the drilled hole on a running eng & with the light on it see if it (the RP) changes. I've never used a dist machine but I'm sure it would show the same thing. Maybe this will help: say the rotor is dead centered on the cap terminal at rest (no mech adv). the other cap terminal is 45 deg away, now if a can with 11 stamped on it swung the rotor around the arc 11 deg (& it will) and say the mech adv added 24 at the crank (which is reasonable/feasible) with reasonable slot lengths which'd be 12 at the rotor, if the mech adv did alter RP (it wont but lets say it will) the rotor will have moved a total of 23 deg (11+12) & there'd be no way it could fire with that great of a distance between rotor tip and cap terminal as that is half the circumferential distance between the cap terminals. Humor me if you will! try the test in the vise. I agree it makes NO sense that since the reluctor moves with adv (& it does) then how could the rotor which is locked to it set in stone NOT move also. it is hard to visually grasp & I could not mentally grab the how it did what it does till this issue came & I went out into the kitchen & grabbed a dist to try to prove my case even tho I've seen it multiple times when doing dist work on vehicles so I know it to be true but unlike Trendz I could not mentally grasp exactly HOW until this. Just Take 5 minutes with your vise or just held in your hands. Hurry, lunch is in an hour and a half & I wanna order a steak (your treat)!

I know what your saying.. like you said.. in a
vise and you twist the upper section the rotor
turns.. thats the mech advance

If the rotor doesnt reach the terminal sooner, how does the timing advance?

It does it by retarding the engine.