Ignition Timing Mechanical Advance

[Av8ferg]

I’m impressed....maybe during this global pandemic you can find a way to make something you can sell later that’s not $549 like 123 ignition.  Making good of a bad situation at Bruce’s house.  Most of America is watching Tiger King and putting on pounds while the Mad Scientist is building contraptions in his garage.  If you can figure out of to make TP out of tree bark you’ll be the next Jeff Bezos. 
in all seriousness, nice job Bruce, keep pushing the envelope for the great good of Z owners.  

[Captain Obvious]

Thanks bud! I didn't start messing around with any of this stuff with the intention of producing anything for sale, but if someone wants to pay me, I'm for sale. Haha!

And speaking of such things... So remember the other day when I told you I broke that brittle plastic vacuum advance bearing holder? It was right after I walked you successfully through how to get YOURS out WITHOUT breaking it?      :

Also remember that I told you I was sure that (using stone knives and bearskins) I COULD probably make something to replace it, but there was no way I was going to go through all that trouble? It was way beyond my pain threshold for an academic exercise?

Well, then there's now:

It's not brittle anymore. 

 

[Captain Obvious]

I also made a plate to lock the vacuum advance mechanism down hard so I could spin the distributor on the bench without worrying about the plates slipping around inside. There are several threads on HybridZ that talk about the advance mechanisms. Here's a couple links. John Mortonson seems to be a big champion of jettisoning the vacuum advance completely and bumping the static base advance up instead. He JB Welded the plates together completely:

https://forums.hybridz.org/topic/21577-timing-an-l28-advance/

https://forums.hybridz.org/topic/49923-advancing-timing/

I didn't want to epoxy everything together, so I made this instead:

Not ready for production, but works for locking my distributor together on the bench!

 

[Captain Obvious]

So I was spinning the distributor on the bench again today and I decided I would put the rotor on it just to see what it looked like as it spun. Nothing really bad happened, but I did pick up a noticeable vibration at certain RPM's. I pulled the rotor off and balanced it on a thin piece of metal.

It's not balanced around the center shaft. You can see from the balance point off center. That can't do good things for spark scatter, bearing longevity, or reluctor gap consistency:

I'm guessing it's because of the metal having a higher density than the plastic portion:

I also assume that the extra material on the opposite end is supposed to be a counterweight. I have no idea what brand rotor this is, but it looks like they needed to add even more:

[Av8ferg]

I’m so jealous you A. Can make all this cool stuff in your garage and B. You must have a nice set of tool and gizmos in your garage to do this.
The metal bearing holder inside the reluctor looks good. Not sure why they didn’t make it metal to begin with. So I’m guessing you don’t need my “extra” parts. I’m impressed you got the bearing holes perfect. The plastic stock ones seemed to have a retaining mechanism on them. Are yours just held in loosely. Probably easier to for Hitachi to manufacture the plastic ones with bearings clipped in. Would be a mess to build this on a line trying to get the bearings in loosely. When you looks at manufacturing things I’m guessing your need to balance these things. Better to minimize the possibility of human error by make a part that is dummy proof and not too difficult to assemble. The KISS principle is so true and I’m guessing it applies to manufacturing.
So on the Vac Advance. Are you saying there is a measurable difference in a Vac Lock out vs Stock? Why would they design this into the system if it was a degrader? Are they some other reasons. Does Vac Advance occurs at low idle of high RPM.



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[240260280]

Many parts are non-magnetic due to the magnetic sensors.... or for lower cost.

CO has a basement full of goodies!

 

 

[240260280]

     

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Edited April 18, 2020 by 240260280

[Captain Obvious]

My laboratory really needs an upgrade. What I really need is big pole barn out-building. I've been told that would make everyone happier. 

My guess on why the originals were made out of plastic was because it was easier and cheaper to make thousands like that instead of machining them out of metal. There might be a little bit of "slippy" feature of making them out of plastic that would be beneficial as well, but I don't think it's that big of a deal.  I just sized the holes a couple thousandths larger than the balls so they would be free to roll instead of binding in the holes. My thoughts on the matter... "They make the bearing cages inside ball bearings out of metal all the time. So why wouldn't it work here?"

As far as a retaining feature for the balls... You can see in this pic that I'm holding the plate up off the bench and the balls are not falling through:

I did this with tiny deformation marks on the other side of the plate. If you look closely, you can see two very small dots on either side of the ball hole. Those punch marks deform the plate and close down the hole a couple thousandths which keeps the balls from falling through:

If I decide I'm going to use this distributor, I could install the balls and then put similar dots on the other side of the plate as well. That would retain the balls in the plate completely. But for all the messing around I'm doing right now, I just wanted to see if it worked. It makes assembly easier because I only need two hands to get in place instead of three. I'm so tired of finding those balls after I have dropped them!

[Captain Obvious]

As for the vacuum advance, I'm just messing around here on the bench with the distributor and I didn't want the vacuum advance to move at all.  Problem was, my new bearing retainer worked so well that the two plates inside the distributor move so nice and easy now that they almost move all by themselves. For my screwing around, I actually didn't WANT them to move around, so I had two choices... I could either install the vacuum pot, or I could just lock everything together with a different plate and skip the vacuum pot all together. I chose the latter.  Since I already had that disk cut as an earlier prototype for my bearing cage, all I had to do was drill a couple holes in it and use screws to clamp everything together.

I think in the application on the car, having some sort of "engine load sensing timing adjustment" feature is desirable. The question is... Do you want to do it with a vacuum pot pulling on the distributor, or do you want to do it electronically using a manifold vacuum sensor or a throttle position sensor instead?

The point made by John Mortonson in those thread from HybridZ is that you CAN do without vacuum advance completely. You'll lose some light pedal cruise gas mileage, but other than that, running with no vacuum advance at all doesn't really have much impact.

The original system does it with the vacuum pot, but I'm just kinda poking around with doing it electronically instead. Re-inventing the ignition controller for the ten thousandth time again.

[Captain Obvious]

So speaking of vacuum advance and load sensing adjustments to the timing...

Aren't some of you guys are running aftermarket ignition controllers or full engine management systems? Are you using TPS or MAP instead of vacuum?

@AK260 , @jonbill , @Zed Head

[240260280]

I wanted to have high advance at idle (say 20) but the problem is that it is too much to crank.  Cars start up nicely with 0 to 5 degrees of advance.

My solution was to run the choke cable to where the (removed) vac advance was and use this to retard the timing to 5 at start then move the choke lever to off to bring the advance to 20 after it started.

Edited April 18, 2020 by 240260280

[Zed Head]

If you want to see what the manufacturers do when they have complete freedom from the mechanical stuff, get an OBD reader with live data capability and look at what your other vehicle does.  It's pretty interesting.  Here's a screen shot from a 2003 Ford, fully warmed up.  Running coil packs (wasted spark) with EDIS, and a crankshaft trigger.  Factory stock.  They control timing and use an IACV to hit a target RPM, apparently.

p.s. I don't have aftermarket engine control, but I've considered it.  I got in to the factory systems and the OBD readers because I had a code on a used vehicle that I could not figure out.  It was caused by a vacuum leak.  This live data is read directly through the PCM.

Edited April 18, 2020 by Zed Head