Distributor curves/timing for '76 Automatic CA - 123ignition

[02sahara]

Car: 2002 1976 Automatic US-California Model

Carb: Solex 32/32 DIDTA

Extras: Thermal-Reactor, EGR Valve, Air Pump and Diverter Valve, etc.

Background: Starts hard when cold and doesn’t run super well in idle. I stumbled upon 123 ignition while researching how to reset engine timing to solve the problem (as one of the first steps).

Progress: Spark plugs and wires are new; no improvement. I already have the 123 dizzy (bluetooth), but the problem starts with the proper timing curves, mechanical advance and vacuum advance/retard. My problem is, that with such model version of the car it seems like the correct information aren’t stated anywhere. Let me explain what information I have so far and was able to figure out:

 

• The only official information that has to be true that I have is from the owner’s manual supplement for the 2002 A CA version: Timing has to be set to 25° btdc at 2.800 rpm.

 

• I took a deep dive in the service manual (Engine Electrical) to figure out what the correct values of the full curve would be and as you can see, only the ti/tii curves of the 008 and 009 dizzies are getting close to 25° at 2.800 rpm (I know that crankshaft=2*camshaft), but '76 USA Automatic California version doesn't seem to be listed here:
  

 

• To make it even harder: The current distributor – and I don’t think it has ever been changed in the car – is Bosch 0 231 170 164 (JFU 4). I haven’t found this distributor listed anywhere in any relation to BMW 2002 yet. Meanwhile I finally got Bosch respond to my request about the 0 231 170 164 dizzy curves and look what I got:
  
  This one does not match the values I've got. What does that mean? Is it with distributors so that the manufacturer has some standard curves, but the BMW adjusted them for each engine? If so, I can simply ignore what the Bosch curves say, correct?

 

• So what I did for now is to look at all the specific values on the following pages to see if something matches more closely to the only information that has to be correct.
  
  
  
  Now take a look at the curves I visualized doing that:
  

 

• So again, only point of reference is 25° at 2.800 rpm
• 2002 A and ti curve values from the service manual aren’t any close to that.
• But instead 2 of the 3 different tii timing values are pretty close. (blue curves)
  Can anyone confirm that I’m assuming right here and if the reference 25° at 2.800 fits well, I can take one of those curves?!
• To move on, I also did some slight adjustment and lowered the curve a little bit (yellow curve) as we have fairly high octane in Germany and in the manual I read somewhere that ignition timing should then be adjusted to 25° at 2.900 rpm (at least). So just to explain what I did there.

 

• Then there is one more thing about the curves which is the vacuum advance curve (yes, my car has a vac line attached to the dizzy). I see that there are to curves stated in the manual. One is to further advance ignition timing, the other one to have vacuum retard.
  
  Now two things I believe retard would be the correct one for my car: Even though it does list a different distributor number (008), it says it’s for automatic models as from 1973. Secondly 123ignition explained in one of there examples that vacuum retard was commonly used a) in US and Canada cars to reduce emission and b) on cars with automatic transmission to reduce rpm when idling. Can anyone confirm that I indeed need to use vacuum retard on my car?!
  UPDATE: I had a further look into the '75 handbook and there it says that automatic versions are using vacuum retard instead of advance. So I'm fairly sure now that this is the way to go.
  

 

• Lastly, and assuming I need to go with vac retard, has anyone experience in setting this up with a 123ignition distributor? I understand most of the manual, but when it comes to vacuum retard there are some confusing information as for example it says that “Please be aware the ignition has to be rotated by ## degrees (retard) to set total timing correct”. So what does that exactly mean? Do I have to do something different installing it? Do I need to alter the mechanical advance curve or turn the distributor itself?

 

A lot of questions, but I just want to have this nice old car run super well and properly set the ignition time. And of course not destroy the engine somehow.
 

Wishing you all a nice weekend!

Marvin

 

 

Edited March 27, 2022 by awesomade
Additional info

[Hans]

Why not try to get the car running with the stock dizzy. First try to wiggle shaft side to side to check for wear.

If OK, how are points, cap, wires, plugs? How are you setting/checking timing?

It might be carb related, but I'd sort out ignition first.

Edited March 26, 2022 by Hans

[Labphoto]

I attached mine, 1975 2002 automatic with a single dcoe 45

2002.123

[Conserv]

My 1976 49-state version (manual transmission) came new with a Bosch 0 231 170 164 / JFU4 (first photo below) — I bought the car new. And, looking at Page 12/1 of the parts catalogue (second and third photos below), it appears that all 1975 and 1976 California-only 2002A’s shared this distributor with the 1976 (manual transmission) 49-state version. It is BMW part number 12111359044. So I believe that your car has its correct original distributor. But I believe it only has vacuum advance, not retard.

 

If you must pass (CA?) emissions, then I suppose the original curve is important. Otherwise, it might not be the optimal curve for your car today.

 

Regards,

 

Steve

 

 

 

 

[visionaut]

The curve you got from Bosch is correct for your dizzy., and shows that it’s vacuum advance only. At 2800rpn it shows you’d have ~18 deg mechanical + ~7 deg vacuum, your Supplement’s quoted value.

Edited March 26, 2022 by visionaut

[2002iii]

I've only ever seen 2002 automatics with a 231 180 003 or 008 distributors. But I know they did weird stuff in 1976. I've never seen a vacuum retard distributor on an automatic.

 

I would start with the timing curve from the automatics in the red box below.

Edited March 27, 2022 by 2002iii
Typo

[Conserv]

On 3/26/2022 at 2:07 PM, 2002iii said:

I've only ever seen 2002 automatics with a 231 180 005 or 008 distributors. But I know they did weird stuff in 1976. I've never seen a vacuum retard distributor on an automatic.

 

I would start with the timing curve from the automatics in the red box below.

The parts catalogue shows three different distributors for U.S.-spec 2002A’s. I only have the BMW part numbers, although I believe Tom Two’s data, in another thread, correlates the BMW and Bosch part numbers. Here are the BMW part numbers, which we know can’t possibly be wrong… ?

 

1. 12111355272 — U.S. 2002A’s up to VIN 2532732 (approx. January 1973)

2. 12111354611 — U.S. 2002A’s from VIN 2532733 through the end of the 1974 model year, and

3. 12111359044 — U.S. 2002A’s beginning with the 1975 model year through the end of 2002A production.

 

The above is from Page 12/1 of the catalogue (below); my copy is updated through 1977.

 

Best regards,

 

Steve

 

 

[2002iii]

Upon further review of the blue book and the parts catalog this is what I've come up with:

 

1. 12111355272=0 231 180 003 — U.S. 2002A’s up to VIN 2532732.

 

2. 12111354611=0 231 180 008 — U.S. 2002A’s from VIN 2532733 through the end of the 1974 model year.

 

3. 12111359044=0 231 170 164 — U.S. 2002A’s beginning with the 1975 model year through the end of 2002A production.

 

 

As to the original problem I would suggest trying to map the curve of your original 164 distributor set to 25° at 2.800 rpm and then replicate that on the 123.

[02sahara]

1 hour ago, 2002iii said:

As to the original problem I would suggest trying to map the curve of your original 164 distributor set to 25° at 2.800 rpm and then replicate that on the 123.

 

Yeah that is actually what I'm trying to do, but wanted to get confirmation about the proper curve. Again:

• Only official values I have are 25° at 2.800 rpm (slightly lower with high octane). But I am missing the full curve. This is why I tried to map some of them in the service manual and see which one gets close to it. Which are 2 of the tii curves. I assume that if one point far from idle speed fits well, the rest of the curve would work too. But exactly this is what I want to get confirmed.
• The Bosch dizzy curves I've got are wrong (think it's more up to BMW to set the proper values ...). They are not using retard – I added a page of the owner's handbook which confirms that (see original posting @2002iii). And even the mechanical advance curve comes close to 25°at 2.800. Sorry @visionaut but your calculation does not work. Especially as 25° at 2.800 has to be measured with vacuum hose off.

But thanks for confirming that my distributor (164) is a correct one. (Also to @Conserv)

 

Edited March 27, 2022 by awesomade

[Hans]

I missed the bit about new plugs and wires. What about points, dwell, condensor, cap?

I would be checking a few basics before plunging down this 123 rabbit hole, as interesting as it may be.

Do you have a timing light? Have you checked the current set-up? Are you getting a healthy spark? Is the timing fairly stable? Your symptoms don't cry out "timing problem to me" as long as it's in the ball park.

[Conserv]

Interestingly, the EPA-mandated tuning specifications for this same distributor in my 1976 (manual transmission) 49-state version specify 25 degrees BTDC at 2,400 rpm’s (with vacuum advance plugged). Below are shown the original sticker in my 1976 (first photo, already disintegrating in 1983) and the repro sticker, before it’s installation (second photo). Thus, same advance as your 2002A, but 400 rpm’s lower.

 

But we should remember that the 1976 (manual transmission) 49-state version, as compared your 1976 2002A (1.) does not have the thermal reactor exhaust manifold, but (2.) does have a slightly-more performance-oriented camshaft — the “famous” number “5”.

 

Regards,

 

Steve

 

 

 

[Mark92131]

On 3/26/2022 at 9:57 AM, Conserv said:

But I believe it only has vacuum advance, not retard. I’ll check later.

 

1976 49 State Manual/Automatic - Vacuum Advance Only

1976 California Automatic - Vacuum Advance Only

1975 Automatics - Vacuum Advance Only

1976 California Manual - Vacuum Advance and Retard

 

Mark92131

 

 

 

 

[Mark92131]

On 3/26/2022 at 6:02 AM, awesomade said:

Background: Starts hard when cold and doesn’t run super well in idle.

 

This is most likely you problem!

 

On 3/26/2022 at 6:02 AM, awesomade said:

Carb: Solex 32/32 DIDTA

 

Most of the remaining 1976 CA cars have dumped the troublesome Solex for a 36/32 Weber that is CARB approved for CA.  I would use an adjustable timing light to verify that you are getting the proper timing curve for your original Distributor through the RPM range and that it isn't showing signs of wear (steady flywheel ball in the viewing port, not jumping around), before departing down the 123 Ignition distributor route.  If your distributor is showing signs of wear, the 123 Ignition is a great option.

 

Is the rest of your smog components present and working correctly, see attached spec sheet.  After verifying the state of your smog components, and after adjusting that Solex for best idle, I would see how it runs at the following settings...

 

25 Degrees BTDC at 1400 RPM

25 Degrees BTDC at 1500 RPM

25 Degrees BTDC at 2400 RPM

25 Degrees BTDC at 2800 RPM

 

It might be happier with earlier advance.  When you need to smog it, re-adjust the timing to the spec on your emission sticker, (25 Degrees BTDC at 2400 RPM?).

 

Mark92131

 

 

 

[John76]

It is interesting to see the centrifugal advance curve for the 059 and 164 distributors on the "76 cars are identical.

The 164 differs with the vac advance only (and a different advance curve), while the 059 has both vac advance and retard.

However, the manifold vacuum advance is not functional on either dizzy if the black electrovalve is energized and all plumbing is per the factory spec....including the T2 temperature switch under the intake manifold.

With the 4-spd CA car, you only get vacuum retard when the coolant temp. is over 150 degrees F.  You never get both adv. and retard at the same time.

 

The red lines in the attached curve show the "BB" (25 deg. BTDC) can/should occur anywhere between 1800 and 2500 rpm with the vacuum line disconnected and plugged.  Full centrifugal advance comes in at 3200 rpm and can be approx. 32 to 41 degrees.

 

The blue lines represent the manifold vacuum advance of 10 to 15 degrees at idle (15.75" Hg) and tapers down to around 0 when vacuum drops below 5" Hg.

 

I think that setting the Static advance to +3 degrees (per service manual) will "lift" the whole curve upwards by 3 degrees.

Am I reading/thinking about this correctly?  

Time for a glass of wine!

 

John

 

 

[02sahara]

Thanks to everyone trying to guide me here – just to sum up about vacuum advance/retard so far:

• Service manual (forum; around '73?) says retard for 2002 A from '73 on ...
• Owner's handbook '75 (not the supplement from '76) generally says retard for 2002 A (and advance for 1602, 1802, 2002)
• "Common use" says both: FAQ'ers experience have only seen advance ... on the other hand retard was often used for US/CA emission and on Automatic cars.
• Bosch distributor curve (164) says advance.
• My emission label says advance.
  Gosh, @Mark92131 I did not realize that advance/retard is stated there! So easy, thanks!

So a lot of contradictory information – but I would assume that MY emission label is the one that's true, even if the '75 handbook generally says automatics are with retard. With that summary, would you guys also see advance as correct for my car?

Edited March 28, 2022 by awesomade