Hi everyone.

I apologize for yet another 123 setup thread
I just spent an hour reviewing the GB thread, and a couple of other 123 threads.

my motor is a stock Djet motor, with 1975 djet components

I bought a used 123, from Jim's well running car
his car is also Djet, on a 2056 I believe

the distributor is the -4-R-V-IE model with the vacuum nipple.
it came set to position #4, from Jim's use.

as I read all of the threads I could find... there are a lot of different recommendations for which Djet setting to use.

I've seen:
#1, #2, #3, and letter A all recommended by different members
(in some of the threads it was hard to track which owners were 1.7 vs 2.0)

I have not yet pulled my distributor. I need to do that to verify which model number is installed. I believe that I checked it years ago when I bought the motor and anticipate it will be the stock distributor for a 2.0/djet/1975. But need to verify


I hope to install in the morning.
because it is so easy to change the setting now, while the 123 is not installed.. I would love to gather more information for this setting... I intend to use the Advance-vacuum as that is how the car is currently running.

(yes the distributor has the spacer)


thanks in advance
brant

I put one of these on my bumblebee last year as I couldn't find a good 039 distributor to save my life. I don't recall what the setting was but "A" sounds correct. Ill go dig up the manual and confirm. The vacuum setting you want retards the timing it idle.

Let me go dig up a manual and see...

oh its a retard?
crap... I thought I read Advance for quicker pick up and less bog

thank you for checking
did you put it on the 1.7 car?
sorry.. you said bumblebee



brant

Yeah, Believe the "A" curve was what i went with.

Advance starts at 1000 and all in by 2700, Vacuum port to manifold in order to pull timing at idle, otherwise you will probably have issues getting your idle speed down low enough.


Not sure what the difference is between the A , B, and D curves as with the extent of the specs listed in the 123 manual they are the same aside from "A" has the dizzy number from a 73 (039 905 205) and "B" has the Dizzy number from a 74 (205A) and "D" is the 75 (205B).

"E" curve is for the 1.7 and starts advancing 200 RPM earlier

the "C" curve they have listed as "Porsche 914" but it looks like 75 Bus dizzy number (205AB) and the advance curve is a lot more sluggish. Maybe used on CA 75 cars to get the cat hotter???

Need to go dig up more reference material to figure out exactly what the differences between the 205,205A and 205B dizzys were. Wondering if the 75 dizzy had a different vacuum setup due to changes in the crankcase vent system in 75??? Either way, I would probably still go with the "A" setting and if for some reason you get strange idle issues then try "D"

Click to view attachment

More Dizzy number reference
https://www.thesamba.com/vw/archives/manual...ne_Up_Parts.pdf

If replacing the stock ‘75 2.0 distributor, you should start with setting ‘B’ if connecting the retard port to the distributor, or setting ‘2’ if you block the TB retard port off.
If you’ve got a TB with both retard and advance ports, block off whichever one you decide not to use.
Regardless off which config you go with, don’t block the vacuum port on the 123 distributor if leaving it unconnected.

Setting ‘A’ as highlighted in the previous post would be for replacing a stock distributor on a ‘73.

Correct, retard. On the 123 you can set it either way but negative advance is what you want for stock operation.

Manifold vacuum is highest at idle and decreases under load so running it with advance on vacuum connected to the manifold would do the opposite of what you want. The advance side of the stock dizzy is normally connected to ported vacuum on the throttle body and is only active for a moment during initial throttle opening. Didnt really do much on the stock setup and they eliminated it in 74 anyways. With a fully digital setup like the 123 the timing response is instantaneous so no need for that little bit of "helper" advance on tip in. It will be plenty responsive.

Still running a stock dizzy on the 1.7 (purple car) as good 1.7 parts are a lot easier to come by. Actually thought about getting that 123 from Jimmy for the 1.7 but its still running really good and I have another Megasquirt system ready to go as soon as it starts acting up.

Tried running a 1.7 dizzy in the bumble bee (2.0) but that extra 200RPM earlier that the advance kicks in causes a somewhat erratic idle on the 2.0.

I suspect you will have issues setting the idle speed properly at setting '2'. Setting 2 has the same total RPM based advance as setting's "A", "B", "D" but will sit more advanced at idle (and thus kick up your idle speed) due to the lack of the vacuum retard.

I don’t think it will matter. 123 is programmed to replace the stock dist. As long as you select the correct setting associated with the vacuum hose connection (retard or advance). At least it didn’t make any difference with my car.

just an update since I left this thread hanging....

I finally installed the distributor on Sunday night.
wow.. it started right up. improved idle

I ran it on setting B with the retard line
it came to me on setting 4... and I bet Jim was running it on the advance side

I'm tempted to try that
but don't really want to pull the distributor again to change the setting
especially because its running and idling great right now... so perhaps I should leave it alone.


one funny coincidence
I installed it sunday night, started it in the garage, ran it up to 180F oil temp
put it back on the lift and got underneath.
everything was clean, everything perfect.

Test drove it on monday for 15 minutes
ran great
came back home, with the temps in the operating zone.
huge oil leak
looks like the passenger side Valve cover gasket has blown out...

weird thing is:
-oil, valve, gaskets were not touched since driving to Santa Fe and back (over 1000 miles)

-no oil leak at all... until I drove it for 15 minutes

-I changed the vacuum hose is the only thing... plugged the Advance port on the TB, opened the retard port for the new distributor.

I suppose I could have minutely changed the crank case pressure by changing that single small vacuum line... but wouldn't think it would be much difference.

so perhaps it was just coincidence?
or does anyone think my small vacuum line change would caused the valve gasket to blow out/suck in?

hunh...that's interesting. So you are using manifold vaccum from the TB if there is less Man vaccum at idle than maybe but I'd doubt it would be enough to suck the gaskets in.

I used what James suggested. Setting 2 with ported advance. I'd try that....car ran flawless and a rock steady idle. I'll assume stock cam Brant.

Stock cam

It’s just got to be a coincidence
A weird one
But nothing else adds up

If you've got good idle, no need to change anything. if you change the distributor setting to #2 (setting B's opposite/equivalent) and use the advance port on the TB, I doubt it would make any difference anyway as the distributor automatically compensates accordingly to match stock performance

BTW, I've change the setting on the 123 distributor without removing it. You just need the requisite small sized screw driver, a small mirror, and some contortion skills to get your head in the engine bay far enough.