123 Distributor Group Buy Thread, Replacement for NLA stock Dizzy's-Order 15 % Discount Options

[914_teener]

On the 72-73 D-Jet FI, at least:
With the throttle body intake facing you, with the TPS on the bottom, the retard port is the 3mm vacuum hose fitting on the left side, facing out. Capping it can be a little difficult just because of access.
The advance port is on the right side, 2mm hose, facing up. Should you cap it, it's simple to access.

Since I do better with diagrams, you're saying the vacuum lines from the throttle body to the stock distributor should be connected as shown in this diagram:
http://www.pelicanparts.com/914/technical_...4_17FI_diag.htm
Correct? Of course, that diagram is for a '70 and my car is a '73, but they should be similar enough.

If that's the case, then my distributor vacuum hoses have been switched/backwards since before I bought the car. However, the canister on the distributor has different size ports, and it would seem to make sense for the port sizes on the throttle body to match the port sizes on the canister. If that's the case, then the diagram is backward.

The red hose is the advance hose, hook this up to the port on the 123 dizzy. Cap the other port, use setting 1.

[BillC]

Umm, nevermind about the backward hoses. Turns out my old distributor was connected just fine and this was simply a case of early-onset CRS (IMG:style_emoticons/default/blink.gif) (shoulda taken a pic before disconnecting stuff (IMG:style_emoticons/default/headbang.gif) ).

[pete000]

OK, got around to put in my 123 Blue Tooth Distributor tonight in my 714 1.8 L-Jet.

No issues at all, just set the car to TDC, pulled the old distributor out, popped in the 123, rotated the distributor body until the green light came on, tightened it down. Programmed my advance curve. Fired right up.

It is really neat to be able to watch the advance working and verify its doing just what you want it to. Car seems so much more responsive. Lots of power and torque no ping just pulls like crazy. I am extremely happy with this group buy ! Thanks for setting it up. The 123 is a very impressive product. (IMG:style_emoticons/default/smilie_pokal.gif)

Here are some pictures and my advance curve. (Not running any Vacuum advance or retard)

[echocanyons]

I didn’t get in on group discount but I picked one up anyway.

Seems like a great addition to my sons McMark built 1996 with Ljet

Does anyone have any suggestions for maps for this?

[pete000]

Here is the map I am running right now. I’m running 100 octain leaded aviation fuel and this map pulls like crazy. Will bump it back to 30 degrees all in on regular pump gas.

[98101]

You guys usually connect the blue wire, right?

[echocanyons]

I believe the blue wire is a ground.

[98101]

I believe the blue wire is a ground.

Yes thanks -- got it working this morning.

It's very cool.

[98101]

Moving this from another thread:

Even though my car doesn't have a stock camshaft, I'm thinking of experimenting with manifold vacuum advance, pulling from four holes that already exist in my manifold. My theory is I should be able to compensate for the Web cam's weaker vacuum signal with the configuration over Bluetooth.

I especially like Mark Henry's suggestion below:

I've always used mechanical advance on dual carbs, but I've heard of peeps using vacuum advance. no idea if it worked well for them. I have seen vacuum used for the bus brake MC, you have to pull off all the runners to get a steady signal. For a dizzy I would also use all four and maybe try running to a small can and take the dizzy vac from that can.

Has anyone tried this yet?

[914_teener]

Just wondering with a programmable dizzy why?

[rhodyguy]

He's concerned about the red advance hose? I was under the impression the model for carbs didn't require a vacuum signal.

[914_teener]

He's concerned about the red advance hose? I was under the impression the model for carbs didn't require a vacuum signal.

You are correct Kevin. If you can modulate the curve digitally with blue tooth .....don.t understand where the vacuum hose would go.

You shouldn.t need it.

[Rand]

Many of us can't use the bluetooth version. Like me with Djet.

[914_teener]

Many of us can't use the bluetooth version. Like me with Djet.

Yes....but he is using carbs....that version uses blue tooth...at least you could with the 123 dizzy.

I am running my djet version with the vacuum advance hooked up.
It is running great.

[98101]

He's concerned about the red advance hose? I was under the impression the model for carbs didn't require a vacuum signal.

Yes, it's running the Bluetooth model now (with carbs) just using an RPM-based curve and the vacuum sensor disconnected. But everything I've read suggests street cars run even better when the ignition timing incorporates both RPM and manifold vacuum*. As I understand it, we want a bit more advance during lean conditions such as cruising down the freeway, and a bit less advance during rich conditions such as wide open throttle.

I am a newbie with little practical experience with this, but I never liked my 009 and I'm skeptical of the idea the optimum ignition timing for street use would only sense RPM while ignoring manifold vacuum. Why did so many stock distributors sense both?

* I'm ignoring port vacuum retard since I read in another thread that was only added as a crude emissions-control measure.

[BeatNavy]

I think you're confusing a couple of things here. The stock dizzys, as I understand it, can have up to three forms of advance/retard, depending on your model.

1. Vacuum advance, which is just the initial advance to help with acceleration and throttle response at low engine speed. Not all 914 throttle bodies have a port for this, and I think the later 2.0 models actually did away with it.

2. Mechanical advance, which is the primary method of advance to "optimize" timing up to about 3000 RPM, when it maxes out.

3. Retard, to reduce emissions at idle.

You've got carbs and I don't know your setup, but the 1-2-3 does all this precisely based on a programmable advance curve because it "knows" the actual engine speed. The vacuum advance and mechanical advance were the engineers' best tools available back then to estimate engine speed and attempt to optimize timing at different engine speeds / conditions. They did an amazing job, but these tools wear out over time and become less accurate. This system is more accurate AND it can easily be changed based on your needs/preferences.

[98101]

I think you're confusing a couple of things here. The stock dizzys, as I understand it, can have up to three forms of advance/retard, depending on your model.

1. Vacuum advance, which is just the initial advance to help with acceleration and throttle response at low engine speed. Not all 914 throttle bodies have a port for this, and I think the later 2.0 models actually did away with it.

2. Mechanical advance, which is the primary method of advance to "optimize" timing up to about 3000 RPM, when it maxes out.

3. Retard, to reduce emissions at idle.

You've got carbs and I don't know your setup, but the 1-2-3 does all this precisely based on a programmable advance curve because it "knows" the actual engine speed. The vacuum advance and mechanical advance were the engineers' best tools available back then to estimate engine speed and attempt to optimize timing at different engine speeds / conditions. They did an amazing job, but these tools wear out over time and become less accurate. This system is more accurate AND it can easily be changed based on your needs/preferences.

Hmm, point taken that the 123 can sense RPM more accurately than the centrifugal weights and springs in traditional distributors -- and this is a good thing by itself. But I don't see how manifold vacuum could be a proxy for RPM. What I'm reading elsewhere suggests manifold vacuum is related to engine load.

According to this GM engineer:

The key difference is that centrifugal advance (in the distributor autocam via weights and springs) is purely rpm-sensitive; nothing changes it except changes in rpm. Vacuum advance, on the other hand, responds to engine load and rapidly-changing operating conditions, providing the correct degree of spark advance at any point in time based on engine load, to deal with both lean and rich mixture conditions.

As I understand the article, manifold vacuum is higher when the throttle plates are closed, lower when they are open. (This effect is reduced somewhat by high-lift long-duration cams.) They will be closer to closed during lean conditions (at idle, or cruising at a steady speed). We need an earlier spark because lean mixtures burn more slowly. With the richer mixture at open throttle we need a later spark to get combustion happening at the ideal time. (Otherwise would we get pinging like my Bosch 009 914 tended to do in hot Phoenix years ago?) If I'm reading this right, we'll get closer to the ideal time to fire the sparkplug by combining vacuum information with RPM information, as the 123 is capable of doing... effectively a 3D map.

Example I in a 123 manual discusses how to emulate a "Bosch-distributor 0.231.170.034 for Volkswagen" which is sensitive both to RPM and vacuum. I'm just figuring this stuff out myself, but my guess is that lots of stock distributors for lots of cars used both RPM and vacuum.
http://www.123ignition.nl/files/manuals/12...al_TUNEPLUS.pdf

[BeatNavy]

You are correct in that manifold vacuum is lowest at wide open throttle, higher at part load, higher still at idle, and highest on overrun (high RPM, closed throttle). In a stock 914 (D-Jet anyway), the mixture is managed primarily by the MPS / ECU based on these conditions.

Someone else can do a better job of explaining how it's done with carbs, because that's more of an "art." Having said all that, you have to determine the best advance curve based on your specific setup. That means a combination of setting / jetting the carbs the way you want them and programming the advance curve on the 1-2-3 the way it makes the most sense for you for different engine speeds. Because I have D-Jet where mixture is controlled by other sensors, I have basically 4-preprogrammed options available to me.

The article you reference makes sense for understanding the theory of optimum advance, but primarily for non-electronic systems.

[914_teener]

You are correct in that manifold vacuum is lowest at wide open throttle, higher at part load, higher still at idle, and highest on overrun (high RPM, closed throttle). In a stock 914 (D-Jet anyway), the mixture is managed primarily by the MPS / ECU based on these conditions.

Someone else can do a better job of explaining how it's done with carbs, because that's more of an "art." Having said all that, you have to determine the best advance curve based on your specific setup. That means a combination of setting / jetting the carbs the way you want them and programming the advance curve on the 1-2-3 the way it makes the most sense for you for different engine speeds. Because I have D-Jet where mixture is controlled by other sensors, I have basically 4-preprogrammed options available to me.

The article you reference makes sense for understanding the theory of optimum advance, but primarily for non-electronic systems.

Almost makes the case to go back to fuel injection (IMG:style_emoticons/default/poke.gif) ... (IMG:style_emoticons/default/laugh.gif)

[echocanyons]

Almost? (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/stirthepot.gif)