with the dist installed of course, if you barely twist the rotor back & forth, not enough to be stretching the springs at all (& the spring tension is there only when twisting in one direction, CW on a SB), then any slop is in the lower tang. Most dists have "some" but you do want it as close to zero as possible.

Yes I'm mimicking an installed situation by grabbing the bottom half of the distributor shaft with my hand and holding it steady, same as it would be installed in the engine, and then grabbing the top part of the shaft where the rotor goes and twisting it I can get it to move a little bit and it would retract just like it was spring loaded.
So it makes sense that it is the advance mechanism and springs causing that.

actually the intergear/dist has to be installed to see how much slop there is between notch/tang when those 2 parts are interfaceing each other. But we should be good once we get the RP taken care of & hopefully the missing taken care of.

I sure hope so, if not I'll just return it, the one nice thing about the firecore distributors is they come with a 1 year warranty.
And I already talked to firecore about some of the issues I've had with rotor phasing and the guy said he'd never heard of that before which struck me kind of odd.
You make mopar distributors and have never heard of rotor phasing issues? How is that even possible?
When I described the movement he knew right away what I was talking about and was adiment that was the advance springs and mechanism.
It's installed right now so I can pop the cap and see how much movement is there.
I want to pull it tonight anyway to get the oil drive gear over a tooth to keep the distributor in the place that it needs to be.
Because right now whenever I modify a new position on the reluctor I have to physically advance the distributor so far to get the same amount of initial timing that the vacuum advance is behind the intake manifold and there would be no way to get the hose on the vacuum can and no way to adjust the vacuum can.
Ricks modified reluctor will be here Thursday.
And I'm hoping that's the answer to this issue, the Miss firing did seem to get better when I had the rotor a little too far ahead of the contact which is when I took that picture and posted it but it was still missing a little bit, not as severe as before however.
The two positions I've been able to try are ether too far behind the terminal that it should be under or a little too far ahead of the terminal it should be firing.
Msd makes a distributor that has an adjustable rotor for rotor phasing but it doesn't have vacuum advance.
Us mopar guys are very limited on distributor choices and it sucks,
Gm guys are spoiled with how many different hei units there are out there plus they get that giant cap and rotor which makes it easier to phase a rotor and makes it to where rotor phasing isn't as critical with such a big cap with terminals so far apart.

So to get the vacuum advance on the distributor to stay pointing at the passenger side fender of the truck do I have to rotate the oil drive gear over a tooth going clockwise or counter clockwise?
Every time I've installed the reluctor ccw on the distributor it requires me to turn the distributor so far ccw that it's pushing the vacuum advance into the back of the intake manifold.

CW, EDIT don't forget to reclock the plug wires, I got bit by that the other day.

Re-lock the plug wires, you mean a jen sure they are pushed down in the distributor cap?

No, just confirm that the #1 plug wire is above the rotor

Oh so I'm going to have to go through the whole process of removing a spark plug and making sure the engine is at tdc on the compression stroke and then placing the rotor under the number 1 plug wire to reposition the distributor once I move the drive gear over a tooth?
I was thinking I could just mark where the rotor is right now and pull the distributor and then move the oil drive gear over a tooth and then put the distributor back in with the rotor pointing wherenitnwas prior to removing the distributor.

yes that would work with carefull positioning, you are just lifting the whole shebang (intergear/dist) up & shifting (rotating) everything an intergear tooth CW then setting it back down into place. EDIT the crank (dampener) ain't being moved the cam ain't being moved so now when done repositioning, if the magnet is dead even with the tooth then it is firing at the exact same point in time that it was before and if our phasing is now good then we're good.

I've decided to just wait untill I have the rotor phased correctly before moving the oil pump drive gear to re-position the distributor.
I should have ricks modified reluctor tomorrow and I'll take another stab at it this weekend.
Based on how far forward unmoved the rotor when modifying my own hole about 15-20 degrees behind the original I'm thinking I'll try the 10 degree hole on ricks reluctor first.
And I'm also thinking with the reluctor installed 10 degrees behind the tooth it shouldn't require me to move the distributor forward much more then it already is originally
Located which would be nice cause then I don't have to re-position the distributor.
If I end up having too then I will, but I'm going to try getting away with not having to at first.

agreed, lets get the phasing corrected then we can get the vac can on the pass side clocked to where is has room to be moved back & forth a bit to set the initial & ideally you would like the #1 plug wire location in the cap to be facing forward toward the front of the car & a bit toward the pass side (on a SB) & lifting/reclocking the intergear locates this. this lets the plug wires nestle the neatest & be the shortest lengths possible. Not a dealbreaker by any means but something to keep in mind.

Well I got ricks modified reluctor installed this afternoon in the 15 degrees behind a tooth location, installed the distributor and fired it up and as I was trying to watch the rotor with the timing light I was hearing a strange noise coming from inside the distributor.
So I pulled it back out and took the cap off and knew inidiatley what I was hearing because there was little tiny metal shavings sticking to the magnet on the pick up coil.
Mind you I set every tooth at .008 with a brass feeler gauge and applied my mity vac to the vacuum advance to insure all 8 teeth were at .008 with vacuum applied as well.
Which doesn't really matter cause I didn't have the vacuum advance hooked up while watching the rotor this afternoon.
Anyways the problems there is a lot of slop on the top part of the distributor shaft that the reluctor slides on and that the rotor sits on.
So because of the place it's forcing the reluctor to smack the pickup coil post.
I did my best to measure the amount of play and it's right around .006 to .008.
So while it's running that reluctor is just wondering all over the place because of it.
Rick from firecore had called me earlier this week cause I had called firecore to discuss some of the movement I was feeling on the top half shaft of the distributor and he said that was normal advance mechanism movement.
Which I know now is not the case, the reluctor should not be hitting the pick up coil post.
This distributor doesn't even have 100 miles of run time and I've just had nothing but problems with it from day one, rotor phasing off so bad it's Miss firing like crazy, movement at the upper half of the distributor shaft.
I attempted to call Rick from firecore back this evening and got his voice mail.
I left a message explaining I'm having some issues with one of his distributors and that id like to discuss them with him.
It has a 1 year warranty so I'm hoping he will send me another unit that has a tight upper shaft on the distributor and being in phase would also be nice, if not I can phase it myself with the modified reluctor from the other Rick guy.
Very frustrating though, my truck has been down for weeks now cause of this distributor.

this is side to side (radial) play, in other words with the gap set at .008" the shaft can move side to side enough so that the tooth are contacting the magnet? that side to side clearance (play) should be near zero.

Yes radial play.
It's been this way ever since I got the distributor from Mancini and I think it's been contributing to the Miss firing problem I've been having.
Every time I tried to describe the movement I was told it was the advance mechanism and springs, which the advance mechanism and springs do cause a movement when the distributor is installed and this radial play is completely different.
So I just wasn't doing a good enough job describing the movement but I I now know that it's radial play, and it's got to be cause of a bad bushing or bearing under the top half of the distributor shaft.

they need to take it back & send you a good one. I ain't familiar with those dists but I sure thought it was too good to be true that the reluctor/magnet gap does not change when the can is applied (but if they have solved that then kudos to them). On OE dists it (vac adv) drastically increases that gap (in addition to the RP change) which does affect cyl to cyl timing.

Well Rick from firecore called me back this evening. And after talking to him he left me feeling like this is gonna be on my end and I'll just have to eat the 165 bucks that this distributor cost me.
He said the shaft assembly is one piece and shouldn't be moving like that, and I said ok well what's between the one pice shaft and the distributor housing? And he said bearings and I said there you go then something there isn't right I shouldn't have this much radial play.
He then said well you've modified the distributor, I said I didn't modify it I've installed different reluctors and I wouldn't have had too if your distributor was phased correctly out of the box.
He said I've never heard of phasing issues so idk what your taking about.
I had to explain rotor phasing to a guy that owns a distributor company 🤣🤣🤣🤣
I'm sorry but that made me laugh.
You are a Mopar guru and make a distributor Very similar to the mopar distributor and you've never heard of rotor phasing?? Really??? That's like Peter Pan saying he's orange.
Anyway he ended the conversation by saying write up an email use your pictures of the rotor phasing issue and the pictures of the radial play of the shaft and use your big words and send it to me and I'll send it to out to our tech department and they will determine if it's due to our qaulity control or not.
I said I'll buy another one if I have too but if I have the same issues with the second one then that's when I'll be done. He then said well who would you go with, what manufacturer?
And I said not sure since options are limited but I'm not buying 3 or 4 of your distributors before I get a good one.
So he basically said rotor phasing doesn't exist and that it's my fault the distributor has the radial play at the shaft cause I installed a modified reluctor 🙄🙄
Anyways I'm thinking about ordering a second one and having it on video when I open the package and install the distributor just to prove to him that his distributors are not correctly phased out of the box and check the radial play of the shaft when I remove it from
The box as well and have it all on video.
And if the second one is the same I'm going to demand I be paid back
In full for both units.
I can't really afford to not have my truck while his "tech department" determines if the radial play at the shaft is their fault or mine.
If I do order a second one everything will be documented by video from the time I take it out of the box.

The advance plate on the firecore distributor is solid, much better then the factory advance plate, I can vouch for their advance plate not moving when the vacuum advance is applied.
All 8 teeth remain the same gap with vacuum advance applied, the issue is the bearing between the shaft and the housing causing the shaft to have a lot of radial play.
But ya read my post above this one, he was kind of a duech on the phone and made him self look pretty bad by saying he had never heard of rotor phasing and that I caused the radial play by installing a different reluctor.

My take: it sounds like you would have to sue him if his 2nd one is faulty. He does not deserve anymore of your business. You could purchase a second one if you are willing to continue this bad deal/& if you are willing to take it up a level (sueing) if it too is junk & I;d say the odds are that it will be bad). Just me I would get another dist elsewhere (I like OE 70's electronic ones myself) & call it over & know that you are not alone haveing been dealt this hand. I had to do that with that crook Ben Gorman of Promax in Indianapolis when he sold me some chinese knockoff EQ heads that were all messed up when I ordered genuine EQ's. there is a company called Promaxx & that is another company altogether (& straight up iirc). EDIT I just read your above post, they just dont want to send you another one for free