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Distributor with vacuum retard but not reversed points


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I'm about to post a much longer piece on Bimmerlife about this, but really you folks should see the meat of it first.

 

For a number of reasons, I went down the rabbit hole with regards to distributors and part numbers. I've long nutshelled the whole distributor question by saying to ignore the "J" numbers, ignore the Bosch numbers—there are basically four 2002 distributor configurations, and you can tell which is which simply by looking at them:

 

  • Centrifugal advance only, as in the '72 and '73 tii (and I guess the ti)
  • Centrifugal advance and vacuum retard with reversed points, as in the '74 2002 and tii
  • Centrifugal advance and vacuum advance, as in nearly every carbureted 2002 prior to '74
  • Centrifugal advance and both vacuum advance AND vacuum retard, as in '75 and '76 2002s.

 

The business about vacuum advance versus retard diaphragms is shown beautifully in this photo previously posted by @'76mintgrun02. You don't need to memorize which is which just like you don't need to memorize which way you need to turn the dizzy to advance or retard it. The dizzy spins clockwise, therefore turning it the opposite direction (counterclockwise) advances the timing, and turning it along the direction of rotation (clockwise) retards the timing. Similarly, if the rod on the vacuum diaphragm pulls the plate opposite to the direction of rotation, it's a vacuum advance diaphragm, and if it pulls it in the same direction as the rotation, it's a vacuum retard diaphragm. The dizzy on the left has standard right-opening points and a vacuum diaphragm whose rod attaches on the left, ergo it pulls the plate counterclockwise, ergo it's a vacuum advance dizzy like most 2002s have. The dizzy on the right has the vacuum diaphragm attached on the right, ergo it pulls the plate in the direction of rotation, ergo it's a vacuum retard diaphragm. The location of the arm where the points usually go forces the points to be relocated to the left side, and for them to be reversed left-opening points. Ergo it's a vacuum retard unit with reversed points for a '74 tii or 2002. All of this is well known.

 

990018539_dizzys76mintgrun02.thumb.png.59178afc4212710ef3cb824996da7fed.png

 

But I saw a couple of posts here on the FAQ hinting that the vacuum retard dizzy actually crept back into '73. Since my '73 2002 "Hampton" is a pretty original survivor car, I checked.

 

I was stunned by what I saw.

 

Below is a photo of my dizzy, Bosch part number 0 231 168 024. You can see that, with the vacuum diaphragm on the right, it's clearly a vacuum retard unit, and yet the points, if you look at them carefully, are standard right-opening points, not reversed points. They're just upside down from how they're normally mounted.

 

IMG_3966_enhanced_cropped.thumb.jpg.c9d2206ea588fd100c30016405b1d5ea.jpg

 

Searching here, I do see a handful of references to 0 231 168 024, but I don't think any of them identify it as this odd mutant combination of normal right-opening points but vacuum retard.

 

More to the point (bad pun), this is on my car, but all this time, the vacuum line has been connected as if it's a vacuum advance distributor, as the car's originality doesn't extend to it having its original Solex with all the vacuum lines, dashpots, and cowl-mounted solenoids intact. I now know what the first thing I'll be doing before I drive the car in the spring will be.

 

Sheesh. You learn something new every day.

 

--Rob

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The new book The Best Of The Hack Mechanic available at https://www.amazon.com/gp/product/0998950742, inscribed copies of all books available at www.robsiegel.com

1972 tii (Louie), 1973 2002 (Hampton), 1975 ti tribute (Bertha), 1972 Bavaria, 1973 3.0CSi, 1979 Euro 635CSi, 1999 Z3, 1999 M Coupe, 2003 530i sport, 1974 Lotus Europa Twin Cam Special (I know, I know...)

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FWIW, 0 231 168 024 (type JFUD4) is a Bosch replacement dizzy. Used on cars with the Pierburg-Solex 32/32 DIDTA emissions carb.

It’s the replacement (ersatz) for the 0 231 180 008 original dizzy. This dizzy was used as early as 6/72 up thru 10/74 on USA 02s, and from 1/73 to 7/75 on USA 02Autos.

 

The 0 231 168 024 is likely similar to the Bosch replacement dizzy for the 02 Turbo (0 231 168 026). IIRC, the Turbo dizzy had vac retard.

Edited by visionaut
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Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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@visionaut I saw your post. I wasn't sure which succeeded which. Intuitively it made more sense to me that there were a small number of these before they went all-in with reversed points, but I trust your research completely.

The new book The Best Of The Hack Mechanic available at https://www.amazon.com/gp/product/0998950742, inscribed copies of all books available at www.robsiegel.com

1972 tii (Louie), 1973 2002 (Hampton), 1975 ti tribute (Bertha), 1972 Bavaria, 1973 3.0CSi, 1979 Euro 635CSi, 1999 Z3, 1999 M Coupe, 2003 530i sport, 1974 Lotus Europa Twin Cam Special (I know, I know...)

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49 minutes ago, thehackmechanic said:

@visionaut I saw your post. I wasn't sure which succeeded which. Intuitively it made more sense to me that there were a small number of these before they went all-in with reversed points, but I trust your research completely.

Rob — I don’t know which direction the points went in the original DIDTA dizzy 180 008. You’re first I’ve read that in the DIDTA replacement dizzy they’re that normal + retard combo. I also don’t know points direction on the Turbo replacement dizzy 168 026.

 

Figured folks that do know the points orientation info for the 180 008 and/or 168 026 might weigh in.

 

Tom

 

Added: the 168 024 was released by Bosch in July 1979.

 

Edited by visionaut
Release date

Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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It's funny just how many variations there are between these Bosch distributors.  It's like no two parts are exactly the same.  Seriously.  They changed almost every part each year, except maybe the points plate, main shaft, gear... probably others; but the center post, weights, springs all seem to change each year (based on visible differences and part numbers applied to them).

 

It's also funny how many different options there were (are still?) when purchasing points and condensers.  There are subtle differences in points for example, such as the rubbing block material, the spring design/materials/strength, the wire orientation/length and so on. 

 

Looking at the points in your distributor, it appears that the wire is at its limit, trying to reach the condenser tab.  Luckily, the retard rotation shortens that reach, as opposed to stretching it.  Bosch did make points that have the wire coming off in the opposite direction, but I don't know what the part number is. 

 

image.thumb.jpeg.ab42a549dc3f929baa4be11964dbadec.jpeg

 

I've uncrimped/re-crimped wires onto them to make them fit with my dwell adjuster.  That was fun.

 

image.jpeg.a15c1ce8c9b13fa26fe235f86d0a6e73.jpeg

 

34 minutes ago, visionaut said:

Rob — I don’t know which direction the points went in the original DIDTA dizzy 180 008. You’re first I’ve read that in the DIDTA replacement dizzy they’re that normal + retard combo.

 

They're "backwards" as seen in the distributor on the right.  (0231180008).

990018539_dizzys76mintgrun02.thumb.png.59178afc4212710ef3cb824996da7fed.png

 

I agree about the four basic types of distributors mentioned above, but within those categories there are two variations, early/late.  They use totally different centrifugal advance mechanisms.  (The very early cast iron distributors are also different, but similar to the early style).  The '75-'76 distributors (and early e21) look like the one on the bottom.  (So does your 024 and Visionaut's 002, as well as my 021.  They're all replacement models).

055.JPG.dcfeb0e84b68bc5c165e9ba13ec3491b.JPG  

 

007.JPG.b1b05b1648a803984e77c0f350a2994d.JPG

 

Sometimes this rabbit hole seems more like a maze.

 

Tom

 

 

Edited by '76mintgrün'02
moving photos
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A puzzle maze it is.

 

Here’s a sample microfiche scan of a piece (source: Bosch Classic). Can’t quite make out the vacuum canister or the points orientation from this pic tho.  :P

 

At the bottom, the ‘common’ description for this particular 0 231 168 xxx series of Bosch dizzys reads:

“For 4-cylinder gasoline engines; with

Speed limiter; ground-destructive (?); neck bearing attachment; Al housing with compo bushings and lubricating felt; ignition cable connectors 7 ø axial; without accessories.”

 

Well enough — But a hellluva lot of other stuff must’ve VARIED… ;) 

 

 

BTW, I count 26 unique Original 02 Bosch dizzy part numbers, plus 9 Replacement 02 Bosch dizzys (7 of which might be still current). 35 Different Models!!

 

And 5 different Bosch dizzy Types were used: JFR JFD JFU JFUR JFUD

J = 70mm Casing
F = Centrifugal Advance
U = Vacuum unit

D = Rev limiting Rotor

R = Resistance Distributor

 

Tom — where you at on this curve? I’m treading water on the bottom right.  Lol

 

Tom-too

B869B455-CC45-401D-A2E4-4BE692B6B2CB.png

2F06378E-B897-46ED-846E-4BBB5AB840F2.png

Edited by visionaut
Added Dizzy type codes
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Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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Ooh, looks what I found digging around... ;) 

 

Details on the innards of the original 0 231 180 008! (and it's replacement 0 231 168 024! )  Sadly I only have these specific dizzy Data Sheets (assembly parts breakdown) for a couple dizzys...

 

They don't even share points part numbers.  Ha Ha Ha...

..

 

Yeah, and a Bosch vacuum advance/retard diagram with non-reversed points, showing they can work a retard regardless of which side the vac canister (or points) is on, based on where they put the hose... lol

Dizzy - advance:retard mechanisms.jpg

0 231 180 008 Part Data Sheet.pdf 0 231 168 024 Part Data Sheet.pdf

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Where we goin’? … I’ll drive…
There are some who call me... Tom too         v i s i o n a u t i k s.com   

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Thanks again guys. Tom, I totally love that dwell adjuster. If I wasn't for the most part a Pertronix convert, I'd have serious lust for it :^)

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The new book The Best Of The Hack Mechanic available at https://www.amazon.com/gp/product/0998950742, inscribed copies of all books available at www.robsiegel.com

1972 tii (Louie), 1973 2002 (Hampton), 1975 ti tribute (Bertha), 1972 Bavaria, 1973 3.0CSi, 1979 Euro 635CSi, 1999 Z3, 1999 M Coupe, 2003 530i sport, 1974 Lotus Europa Twin Cam Special (I know, I know...)

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