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123 Install Results...and a Surprise


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I installed a 123 Ignition distributor (Bluetooth version) into my project ti-wannabe today ('70 body, '75 block, '83 head, dual side draft Solexes).  I very much appreciate all of the efforts FAQers expended to post the 1,000's of comments re: this product, its installation, results, experiences, and the plethora of suggested advance curves.  These are tremendous resources which directed me to a successful install.  The surprise is at the end...


I read and re-read numerous posts re: the 123 and recorded many, many advance curves to help me decide an initial curve.  I crudely graphed several examples of ti-type curves (see photos).  Most of them looked about the same.  I eyeballed an average of each point, made my initial curve (see photos), and put it into the iPhone app. 


Relatively easy and just as most of you described.  Bosch red coil and Bosch 1.8-ohm resistor installed.  The magic under-the-rotor green light was easy to find.   iPhone 123 app recognized 123 immediately.  I used only the TDC on the flywheel during installation.  The new coil and resistor were installed in the same locations and with the same wirings as the old parts. 


Did not happen. Neither did the subsequent 10 adjustments and attempts.  I did the following:

1.  reset the 123 electronically from scratch, i.e., started, over,

2.  set TDC for both the flywheel and the timing chain , and

3.  manually tweaked the initial advance by rotating the 123 "a little" CCW. 

After 3 additional tweaks the engine started.  Several posters have stated the green light is only a staring point for static advance. Adjusted timing to 25 BTDC at 2,200 rpm.


123 seems to be the bomb.  Car pulls strongly in all gears; no skips; no flat spots.  Much better than before.  The initial curve seems to work swimmingly.  Will adjust the curve and play with the 123 "tuning" function for fun and educational purposes.


While locating the TDC line on the cam flange, I noticed a big chunk of the flange to which the sprocket is bolted is missing (see photos).  All bodily functions, biochemical processes, and metabolism ceased for a minute or so.  Examination suggests the chunk is from the part of the flange which immediately surrounds what appears to be a steel alignment dowel.  The 4 sproket  bolts look tight, undamaged, and in good order.  The first thing I did post-physical recovery was use a magnet-rod to probe into the depths of chain path.  Predictably, nothing was retrieved.  This damage could have happened recently or long ago.  Dunno.  Maybe the chunk is in the oil pan.  ***I will very much appreciate your comments on this issue.***


Now, my tii is next.


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WHoah! That's a big chunk of camshaft missing....


If it happened inside the motor, it'd assume it was a while ago and thankfully made it past your lower timing sprocket/chain into the oil pan. If it's down there, I'd think it's unlikely to cause you too much trouble. 


If it happened outside... I wonder if someone dropped the head, camshaft, or combination of the two when replacing or repairing. 


If I were you, I'd be seriously tempted to remove the upper timing cover and pull that sprocket off to make sure there aren't any other hairline cracks in the face that are waiting to propagate and cause a grander failure. If not just to to get a better look at what coulda caused it.


Or you could just run it... the dowel obviously doesn't see any load, it's just for locating.


Just make sure you don't skip any teeth or loose your timing. 


Another thought... What coulda happened is maybe the pin got driven in at an angle, bound and became side loaded, and blew out the mounting flange? Just shootin' spitballs here. 

Edited by 2002Scoob
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Off topic but +1 for the hand drawn graphic with multiple data points + notes + different symbols for each. Man after my own heart. Old school!

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1973 2002tii (2764167), Baikal, Rebuild blog here!

In the past: Verona H&B 1973 2002tii (2762913); Malaga 1975 2002; White 1975 2002

--> Blog: Repro tii cold start relay;   + --> Need an Alpina A4 tuning guide? PM me!


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The sprocket alignment pin looks bigger than the camshaft hole and it popped the cast cam rim when it was driven in.

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A radiator shop is a good place to take a leak.


I have no idea what I'm doing but I know I'm really good at it.

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All bodily functions, biochemical processes, and metabolism ceased for a minute or so... Sucks getting old, huh Larry? ??. All Jokes aside, I need to come down to see your project.



(1973 Fjord Blue 037) Vin 2588314- Build date February 6th, 1973- delivered to Hoffman Motors NYC February 8th.

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Your advance curves don’t look anything like what I see in the Blue Book. The tii maxes out at 25-degrees BTDC...

Sent from my iPhone using Tapatalk

January 30, 1973 Agave tii

April 24, 1974 Chamonix Turbo (German delivery)

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2 hours ago, Lengrep said:

The tii maxes out at 25-degrees BTDC...


USA Version only, Early ROW Tii's maxed out at 24-28 Degrees BTDC at 2500 RPM and were later adjusted to 20-24 Degrees BTDC at 2500 RPM when Germany established .4 g/liter lead content limits in their gasoline.



1970 BMW 1600 (Nevada)



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I was going for USA versions for a ti and included a tii curve for comparison, and, besides, I might need a tii curve when I install a 123 into my tii.  From Manual at end of timing spec table:  tii maxes at 27-32 @ 3,500 rpm (footnote 4:  "...for USA version").  Such is indicated by the two Xs at the end of the group of curves.


JsnPpp:  Sometimes old school just feels good.


Walter:  Growing old ain't for sissies.  Come on down, my AR backroad driving bud.  I got beer.


Scoob:  Thanks for your thoughts.  Can a TC sprocket be replaced by removing only the upper TC cover?  I suspect not.

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41 minutes ago, 2002#3 said:

Can a TC sprocket be replaced by removing only the upper TC cover?


Yes.  I did it when looking for markings on the end of my camshaft. I made a block of wood to keep the chain on the sprocket and maintain alignment.  


Used a piece of paper to take a print off of the oily sprocket and used that to cut out a block to fit underneath it, sitting on the top of the lower cover.




I suppose you might need to remove the sprocket completely, to get a better look at the end of the cam.

Sometimes I use the camera to look closely at things.  Take a few shots and then zoom in using the computer screen... and then post them here!


Edited by '76mintgrün'02
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I very much appreciate your taking time to share your approach and photos.  Thank you.  I was wondering how that could be done. 

Will your approach work for a complete replacement of the sprocket if removal and simple exam suggests such?

I will certainly report the exam and replacement if necessary and will post photos accordingly.  


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I always zip tie the sprocket to the chain to maintain the timing. That's horrible - not so awful you won't drive anywhere until you swap in a new cam, not so great that you won't drive with paranoid fear thinking the worst of every little noise, somewhere exactly in the middle. I'd see it as an oportunity and buy a 292, that'll really wake up your engine with the sidedrafts.

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I'd for sure be afraid to ring it out....but would be content puttering around and cruising with a moderate level of paranoia. 


In my Brain-FEA, the cracking/blowout doesn't effect the overall structure... but It's a pretty easy exercise to take a look-see.


Ya just gotta be ready to seal the front cover back up properly by replacing gaskets, using silicone, and tightening the bolts in the proper sequence so you don't get leaks in the bottom corners on reassembly. 

Edited by 2002Scoob
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