For those that have a 123 Distributor, I need some help setting my timing. I'm probably over thinking all of this but I've read several different threads on setting the timing with this distributor and I have interpreted them all differently.

I'm running a stock 2.0 w/ DJet.
The 123 distributor setting I'm using is 'B' (negative advance), and has a max advance of 22 @ 2700 RPM.

With my new-school timing light that allows me to set the advance, (with vacuum line from the tb plugged) do I:

- Set timing light to 27 advance and rev to 3500 RPM and time to the TDC mark?
- Set timing light to 0 advance and rev to 3500 RPM and time to 27 degree mark (same as above, right?)
- Set timing light to 22 advance and rev to 2700 RPM and time to TDC mark?
- Something else?

I feel like an idiot asking this question. Timing is such a basic thing and I had no problem with the stock distributor and an old school timing light, but I've read more than one thread on how to time with the 123 distributor, plus I've also read that there's 10 degrees advance added at static on these distributors.
Help!

You are looking for total advance w/o the vacuum advance so 1 or 2 is correct. Then hook up the vacuum and see what your total advance is. I would say 35-ish or less is OK but don’t adjust to get 35 with vacuum. Just see where it’s at. If it’s more than 35-ish you might try driving without vacuum connected and see how it runs. I didn’t use vacuum on my carb’ed 1911cc with 123 and it ran fine.

i think all your questions will be answered in this thread: http://www.914world.com/bbs2/index.php?sho...8153&st=120

i just went back over mine due to idle being just a bit higher than i wanted it to be. did this yesterday, it’s a ‘75 D-jet stock everything . and like you i have it set on B. the carb guys don’t use the vac same and use that 1 or 2 setting with positive, but almost everybody here that’s running d-jet and use the negative vac(retard) #B, timing is set same as the manual says to, at 3500rpm, so that if your fan is marked at the 0, use the light and get it set to 27degrees before tdc - thst is with no vac line hooked up, all hoses plugged but vac on the distributor is open. the. once this is done your idle will be high but as you hook up that vac line (retard) to the distributor it should pull it down to 900-1000.
now this all assumes your valves have been set and the CHT is correc you have no vac leeks and the mps is tuned correctly.

ok, now i just went back to recheck mine too and i have my idle one warm end up good, is about 1100. it’s a bit higher than i’d like and i can adjust the idle mix on the ecu and drop it about 100 or play with the MPS but i like where all my AF readings are so i am not doing that, it has more to do with the CHT i think, because idle cold is good, then slightly warmed up as the aux idle air valve closes it slows a bit too much but within 1-2 minutes it’s right at that 1050-1100 and stays right there . could be the resistance of my cht as it warms up is not correct, but gets there, and i suspect that because of it sits when i run in the store, come out , due to that heat sink effect the isled is slow for about 60-90 seconds before it comes back up to normal.
i’d like to get the idle at 900, but if i make adjustments to do that the heat sink issue is way worse ,

so i will say that with the 123ignition and a new clean tps the car has never run better.
read thru that other thread, let us know how it tunes up.

Phil
@rjames

Thanks Phil. I’ve read that thread several times.
The way you described is how I timed it and I’m also using ‘B’ setting on the dist.
I revisited my timing because I’m also trying to address a high idle and thought maybe I had the timing too advanced. My idle is at 1100 and it bugs me.
I’ve already chased down all vacuum leaks (yes I’m sure- there’s a whole other thread I posted on that a while back).

The only way I can bring the idle down is by adjusting the MPS to over-richen the mixture to 10-10.5 AFR, which is way too rich. If I lean it out to anywhere from 12-14 the idle goes back up to 1100-1200rpm. Otherwise the car runs great and my part-load and WOT AFR #s are good.

I know some have had a higher idle after installing the 123, but there are also others who haven’t.

@drphil914

sounds like we are in the same boat. i have adjusted the distributor to take out just a few degrees of advance and the idle is spot on at 900, when warmed up, but idle is then just a bit low until warmed up. so right now it seems i live with it like it is as it runs great. oh and with my stock distributor i still had the issue, i had the idle dialed in but it was only good when warmed up, it was too low cold ..
if anyone has a solution for this idle issue with the d-jet, let us know!

Is your AAR working/opening up when the engine is cold to jet more air in?

Make sure you are using ported vacum from the throttle body for vac advance and not manifold vacum.

the AAR is opening correctly and here it’s been pretty warm, 80’s so car warms up a and the AAR closes rather fast. i think i you’ll be better if it stayed open a bit longer, as the cht warms up then it balances out and idle is good and steady at about 1100. so maybe the AAR is closing too fast?
yes the vac is coming off the TB on back side (it’s a 75 so only one port not 2) and goes to the distributor.

anyway i am going to think about the AAR. it’s going to be cooler next weekend so will see how thst effects it but generally the cal loves the cooler dense are and seems to run even better in cold weather

I’m using setting ‘B’ on the distributor which uses manifold vacuum to retard the advance at idle with a TB that only has the retard port.

What year is your Throttle body? Post 73?

Post a picture looking down the throttle body and where the hole is for the vac port of the TB. For ported the hole should be on the atmosphere side when the TB plate is closed.

I'm not using vacuum for advance.
My late TB only has a port below the butterfly for vacuum retard, which is connected to the distributor. Throttle body is from a '75.
Seems odd to me to time the engine to the 27 degree mark when max advance on the dist is 22 degrees. Wouldn't that make it too advanced at idle?

-

So I'm confused.

The original dizzy on the 914 had a dual vacuum pot which used two types of vaccum. The retard port used manifold vacuum while the advance port used ported or atmoshere vaccum just in front of the throtle plate to advance the spark curve for part throttle situations.

When I had first installed the 123 I used the vacuum port on the dizzy for vaccum advance and the appropriate curve for that engine....matched components for D-jet.

I know on later models they used different distributors as Porsche had to comply first with NOX and then emission regulations in the US nearing the end of its production run.

After 73 it's a toss up of what curve setting to use if it is a switched 123. Just use the one that gives you the most power.

I'm not sure if you have the vacuum port on your 123 dizzy and given your post I'd call them to make sure what curve to use. I don't have my car anymore but I posted the initial group buy years back and after I dialed it in it ran flawless for years. It idled rock solid at about 800 rpms when warm. I had the stock cam.

The first thing I'd check is to make sure of your ECU number and other components are matched for your engine.

Frankley who gives a whim about retard curves after the car is smogged.

I'll also asssume you have the stock cam...if not...it might idle higher depending on the profile as you may be aware.

Good Luck.

I have the vacuum port on the dizzy connected to the manifold vacuum port on the TB which is used to retard timing at idle. Using setting ‘b’ which is the correct setting for the stock dizzy the 123 dizzy replaced. Setting ‘b’ does not use vacuum advance.
Stock djet with correct parts. Smog stuff has been removed. Idle was 900 with the stock distributor.

I am hoping that someone can explain why when the max advance on the 123 dist is 22 degrees I still time to the 27 mark.

Understand your TB has a manfiold vacuum port.

The 123 curves are supposed to mimic the stock distributor curves and if it is maxed out for curve B at 22 degrees why are you using curve B and why are you timing to 27 degrees? Do you want it to behave like a stock distributor to limit idle emissions? What "smog stuff" did you remove? Sounds like your car is post 74.

Before I installed my 123 I found Brad Anders bit on stock dizzies extremely helpful:

https://members.rennlist.com/pbanders/distributor.htm

I appreciate all of the responses.
Yes, my car is a '75 and only has the manifold vacuum port which was used for retarding the timing for emissions as I understand it.

Why am I timing to 27 degrees? Because most every thread I've read on timing a stock Djet with the 123 dizzy says to time it to 27 degrees. But that's really the basis of my question- why 27 if the max advance on the 123 dizzy is 22? I also just learned that max advance on my stock distributor is also 22. (039 905 205 A in the chart below) So I guess now it's a general question of why do we time our engines to 27 if max advance is 22?
Click to view attachment

And I'm using setting 'B' in hopes of getting the idle down to 900-1000 RPMs instead of the 11-1200 it sits at now. That said, using setting 2 on the dizzy and not using vacuum off of the TB (and plugging the TB vacuum port) yields the same result. Both 'B' and '2' settings match the stock dist that the 123 replaces.

Car runs great otherwise, but the high idle sucks. The only way I've been able to bring the idle down is to over richen the air/fuel mixture, which I don't want to do.

This is what I'd do:

Make sure you have no leaks and a functioning pvc stock set up. Make doubly sure you have NO vacuum leaks.

Since you already have the switched 123 for D-jet find a 73 or 74 throttle body and set the curve to the switched curve using vacuum advance.

Of course...set your static timing first and put a plug on your manifold vac port on the TB.

The only reason they used the manifold vacuum port was to reduce emissions at idle so why compromise power if you don't have to?

Good Luck.


Edit:

Sorry your question:

Why if the dizzy advances to only 22 degrees am I timing to 27?

You would time to 22 degrees at the specified rpm for which is specified in the installation manual for the 123.

So with a retarded spark with vaccum the HG reduces to zero at WOT.. the total is about 27 degrees but the starting reference is different in crank degrees. So if your static timing is at idle it sounds like you are off the difference or 5 crank degrees of advanced hence the high idle....IF you don't have any vacuum leaks.

That is my attempt to answer it.

hey 914 teener, what curve did you run?

“ I'm not sure if you have the vacuum port on your 123 dizzy and given your post I'd call them to make sure what curve to use. I don't have my car anymore but I posted the initial group buy years back and after I dialed it in it ran flawless for years. It idled rock solid at about 800 rpms when warm. I had the stock cam. ”

if you had a 2.0 d-jet did you run the 2 curve no vac hook up?

Phil

I didn't have a 2.0. @DRPHIL914 . I had a 1.7 and I used curve 2 per the manual that came with the 123. I wasn't confused by what someone else had posted because no one had posted anything about it before.

If you follow the manual religously it does work as designed. I had a different goal, my car was a near stock restoration and since I could no longer find a dual diaphram for the car I decided to buy a near stock electronic distributor because I am an enthusiast not a car collector. A car collector bought the car and I sold him the old dizzy with it....and with a leaky advance/retard vacuum cannister.

It drove tremendously after that and it was surprising the spunk in a stock 1.7 that is properly tuned...it was a game changer and x'd my plans to put a 2.0 in the car.

Edit:

This is the one I bought:

Porsche 4-R-V-IE

Again...It was a stock restoration effort and used everything the car had ...EXCEPT the manifold vacuum port at the TB which I capped at the TB. The electronics already had the retard degrees acconted for in the advance profile. If you read Anders site how that cannister works...it becomes more understandable, if that is your thing. I'm an engineer so I want to know how everything works first.

@rjames
@914_teener

after this thread got started i decided to revisit this issue on my car, being i had the height idle as well, once i used my timing light it says 1250rpm, anyway and some chatting back and forth on pm with these 2 fine gentleman, i thought i’d post my results from this weekend of testing and retuning .
I have been running the “B” curve and thought that was correct but looking back again at the book, my ‘75 diet has the 205B/021 distributor and that coincides with the “D” curve but i think either tB,C or D can be used here if you go with the retard vac line to the vac on the distributor.

while on that curve, over the past 2 years since i got the car back in the road i had an MPS fail, and had issues with getting my idle right. i have an AF meter, and i have no vac
leaks, engine has about 60k miles, i out everything new on this when i put it back in.
SO, all that said- rjames and i discussed this and looking at the programmed curves etc i decided to try C&D, reset
timing as see what worked better- i found that the B&D didn’t heel much different, and right now i am using the C , partly due to the max advance is at 3400, and it feels much stronger in the higher rpm range now. my idle is right about 850-950 depending on if my lights are on or not, it drops 100 with the current draw but is not steady and smooth- i still had an issue with idle being low for first minute upon cold start up(yes Aar is working perfect ) so i switched out my CHT to the new one from 914rubber, and this actually helped some, i could advance it some and that would help, i set timing at 22 not 27, but also i can tell you from charting my head temps that it is running cooler head temp now at this setting. maybe because it’s just a bit richer, or just the timing and advance change not sure but once warmed up it’s really right on the nose, 850 smooth
with lights on!!! yay!! one other issue, i noticed that my oil temps start to climb when it sits and idle in driveway for 20 minutes, gauge
says 230-240, wierd since i have an auxiliary oil cooler and fan , - soon ans i drove the car around the neighborhood it dropped
to 190, head temps at this same time we’re low at 240 while sitting there.
any thoughts on that???

i just wanted to share this here rather than a new thread as it pertained to what james us going on and figured it others were maybe interested and could comment.

Phil