Locking out advance with welds

[Johnny Mac]

Not really, as Kit is talking about tolerances being affected by one weld pulling things off center and the other weld not being able to recover it.
He is used to things being extremely accurate, and it bugs him when they are not.
Problem was/is nothing on these cars is.
I get what he is saying, I just don't think it would be near enough to make any real difference.

Yeah no disrespect intended. My tach welds were good enough for my slowboat bracket car. lol. I understand the mneticulousness of what is being said now however. Makes sense i suppose, but as yourself, i guess i'm a little sloppier in my methods.

 

[Johnny Mac]

Back to basics here.... This was asked by the OP in relationship to working with a fitech. The cat has been skinned 48 ways...and it still won't work with a fitech...done-zo.

 

[whitepunkonnitro]

View attachment 1714996061
The inner shaft with the spirals is a bit loose to the top hat due to clearances. Welding will very likely, pull the top hat to a side, or make a wobble. And pulling to side, changes when spark triggers, advancing on near side, retard on far side. The set screws as suggested and use of dial indicator can null out run out. On VR distributors, welding may result in magnetization, and that can mess with sensor signal. VR sensing is inaccurate enough in standard form. I use tab wheels with significantly increased diameter, and digital outputs for accurate timing reference. I found that blueprinting distributors helped, improving the sensing technology with optical tab sensing is far superior, and cost effective, with features not possible with VR.

You can say nonsense and that is OK. My wife points out your white Dart, on occasions when it is stalled at a busy intersections in M'boro. She looked at me and said you have given me cars to drive for over 40 years, they are not new, but I have never been stalled.

Ha! I'll eventually fix the gas gauge in that thing. I'm one of those eternal gasoline optimists that is forever coasting into stations...sometimes.. OK, often, I miss.
Back to the original issue. If the weights are slid all the way out, and evenly bottomed in their respective slots when you weld them, the relationship of the upper and lower half's cannot change.
It would be more likely there be a varience from the factory using two different springs, than two even welds.
Been doing them this way since the 70s and have had zero issues, ever

 

[TrailBeast]

So, just one more thing if I may please.
One could move the weights to full advance, mark the top and bottom shafts then throw all the weights and springs away along with the swaged on slotted piece and weld the two shaft sections down inside the top where the clip is with the marks lined up.
(loosing about 1 lb of pointless rotating mass) AND having a locked out distributor.

 

[Johnny Mac]

So, just one more thing if I may please.
One could move the weights to full advance, mark the top and bottom shafts then throw all the weights and springs away along with the swaged on slotted piece and weld the two shaft sections down inside the top where the clip is with the marks lined up.
(loosing about 1 lb of pointless rotating mass) AND having a locked out distributor.

as long as you're ready for the 55 RWHP you've just unleashed ;)

 

[whitepunkonnitro]

So, just one more thing if I may please.
One could move the weights to full advance, mark the top and bottom shafts then throw all the weights and springs away along with the swaged on slotted piece and weld the two shaft sections down inside the top where the clip is with the marks lined up.
(loosing about 1 lb of pointless rotating mass) AND having a locked out distributor.

Well, yeah, I guess you could..but then accuracy would become a big issue.
Better to just find a Lean Burn distributor at that point.

 

[KitCarlson]

Ah, ok then.
I never personally verified if they aligned closest at idle or full throttle.
I guess I just assumed it was at idle and it got farther away as RPM's rose, or was before the terminal at idle and after at WOT and full advance.
So they align closest at WOT then.
Thanks for answering that.

So, just one more thing if I may please.
One could move the weights to full advance, mark the top and bottom shafts then throw all the weights and springs away along with the swaged on slotted piece and weld the two shaft sections down inside the top where the clip is with the marks lined up.
(loosing about 1 lb of pointless rotating mass) AND having a locked out distributor.

And about 5 minutes with a variable speed hand drill, with drill, tap and cutting fluid you could have it adjustable. I have done this for over a decade on more than a dozen electronic advance distributors without a slip or lost screw. You can use loctite, and or second screw on top the other if worried about that.
There are also locked out lean burn distributors, but as Pace said they are troublesome. There is a Mallory trigger wheel rotor, that can be used with optical vane type sensor, for digital output, getting around VR sensing issues of runout, RPM related timing errors, and decoding VR signal. The optical sensors are inexpensive, and automotive temperature rated, or use an expensive Uni-lite trigger. The wheel has 8 slots, for ignition triggers, the radius is much larger, so much more accurate than a reluctor used in Mopar electronic distributor.

 

[KitCarlson]

About rotor phasing, since the rotor and reluctor are situated on the top hat and are not adjustable being fixed to each other, the trigger point is by the pickup in the distributor body. To change phasing, you need to alter the pickup to distributor body, that references the cap. The cap locator is often tab at vacuum advance unit, or plate on lean burn distributors. But the cap clips allow very limited adjustment. The vacuum advance plate can do that, moving pick in a sliding fashion, with a means to move and lock down. I have used a longer screw in the capacitor hold down, on points distributor for that. Or drill and tap plate at similar location.

So if you inclined to worry about the end of slot, to weld on, it is not good logic, because phasing is not set there unless you break, and modify reluctor to rotor position. An example of that is the BB flip that moves the reluctor a tooth width, for CCW rotation, placing trigger in correct trailing tooth edge.

 

[subcom]

Thanks to everybody for the feedback and ideas.

Just for closure, and not to continue the debate of pros vs cons vs alternatives, can any of you share pics of the welds you've done on distros to lock-out the advance?

 

[whitepunkonnitro]

About rotor phasing, since the rotor and reluctor are situated on the top hat and are not adjustable being fixed to each other, the trigger point is by the pickup in the distributor body. To change phasing, you need to alter the pickup to distributor body, that references the cap. The cap locator is often tab at vacuum advance unit, or plate on lean burn distributors. But the cap clips allow very limited adjustment. The vacuum advance plate can do that, moving pick in a sliding fashion, with a means to move and lock down. I have used a longer screw in the capacitor hold down, on points distributor for that. Or drill and tap plate at similar location.

So if you inclined to worry about the end of slot, to weld on, it is not good logic, because phasing is not set there unless you break, and modify reluctor to rotor position. An example of that is the BB flip that moves the reluctor a tooth width, for CCW rotation, placing trigger in correct trailing tooth edge.

The cap is fixed in relation to the distributor body, the rotor fixed in relation to the upper distributor shaft.
Change the position of the upper shaft, and you change the point where the rotor is aligned to at the time of fire

 

[KitCarlson]

Nope, you have to rethink that. The rotor is fixed in relation to reluctor, Ignition happens when trailing edge of reluctor tooth is aligned with pickup nub. With the pickup fixed to body, the phase will be the same. It does not matter if you rotate the shaft, or body. But if you move the pickup, the phase changes, because the cap terminals are referenced to body.
Perhaps Greg can understand, and then use better words to help explain.

 

[whitepunkonnitro]

The cap is fixed in relation to the distributor body, the rotor fixed in relation to the upper distributor shaft.

Nope, you have to rethink that. The rotor is fixed in relation to reluctor, Ignition happens when trailing edge of reluctor tooth is aligned with pickup nub. With the pickup fixed to body, the phase will be the same. It does not matter if you rotate the shaft, or body. But if you move the pickup, the phase changes, because the cap terminals are referenced to body.
Perhaps Greg can understand, and then use better words to help explain.

No, you are confusing ignition phasing with rotor phasing.

 

[KitCarlson]

Nope talking about rotor and cap terminal phase, at point of ignition, sorry to be difficult, please read my words, try to understand.
Maybe this will help, what happens if you clock the distributor gear a tooth, then readjust timing? The rotor phase to cap stays the same. If you lock top hat to inner, or outer part of slot, same happens you are moving both rotor and reluctor on shaft. Then rotating distributor, adjusts but no change in rotor to terminal phase, because ignition event is timed by pickup location, that has not moved in relation to cap. Maybe you are thinking rotor and reluctor are clock different with where you weld, but the rotor index slot, and reluctor pin index are on top hat.
I guess we are done, but feel free to prove me wrong. Booger up a couple old distributors by welding them up different, and view rotor with timing light, post them pics.

 

[TrailBeast]

If you turn the distributor body on a locked out distributor 10 degrees, the cap and pickup coil both move 10 degrees, as does the terminals inside the cap.
The only thing it changes is to make the spark sooner or later in relationship to the crank. (the rotor still does and always will point to the same place inside the cap when the spark happens no matter the distributor position )
The only way to get the locked out distributor out of phase mechanically as far as the spark is concerned would be to either move only the reluctor or only the rotor and the normal distributor isn't made that way.

With a mechanical advance distributor, the reluctor and rotor both move forward at the same time causing the spark sooner as well as advancing the rotor tip.

When vacuum advance is in use it only advances the pickup coil in relation to the reluctor and the rotor tip remains where it is.

AND it makes zero difference what the position of the bottom shaft in relation to the top shaft is because the reluctor and rotor are both fixed in relation to each other on the top part.

BUT "It still won't work with an FItech ignition 499 out of 500 times.

That help or make it worse?

 

[RustyRatRod]

The OP asked another question in post #34 if yall can stop long enough to answer it.

 

[TrailBeast]

The OP asked another question in post #34 if yall can stop long enough to answer it.

Saw the question but I don't have a pic because I don't have distributor welded like that.
I tacked a small section of 1/8 rod in the ends of the slots to limit mechanical advance travel with mine.

Could probably find pics on the net, but possibly not one of ours.
I can check.

Yea, not finding a pic of one welded.
Just a 1/4 or so spot with a mig at the top of the weight posts to the slot edge will do it.