Yup, Dave's got it.

The vacuum chambers (of any sort) are obviously sealed, except for the port/tube. When you apply vacuum to the chamber, it pulls the advance mechanism. When you leave the port open and disconnected, changes in the advance mechanism (because of centrifugal advance) will essentially work backwards down to the vacuum diaphragm. These movements of the vacuum diaphragm force air in and out of the vacuum chamber. If the port is plugged, you're restricting that movement because not the vacuum chamber is sealed and it become a pressure chamber. That pressure buildup can have erratic effects on timing as the air pressure tries to force the advance mechanism back.

Maybe this would be clearer. If you take a plastic soda bottle, and you cap it, you can't squeeze it like you can if it's not capped. The vacuum advance mechanism is meant to move, so if you cap it you're stopping or reducing the movement of the whole advance mechanism.

OK, I placed my order. Looks like we're still in 5% discount territory.

I didn't order the coil because the car already has a 2010 Pertronix "Flame Thrower." Let me know if this wouldn't work.

If anyone's in the Seattle area and wants to make sure I don't screw up the install, I'll be happy to drive to your place (on a less rainy day... car isn't set up for rain).

I'm guessing my car has issues beyond ignition timing but maybe easier to fix those things with decent timing set up.

--Michael, novice in Seattle

I hope to get my order in right before the deadline this week end...

For those replacing the Bosch 009 here is the curve for that. It is from the TUNE Software but the values can be loaded into your Bluetooth. It will be a good starting point. No vacuum on this curve
http://123ignitionusa.com/content/Example5.xml
Here is a link to the download curves page. Somewhat limited but there is one near the bottom for an 009 with vacuum too.
So far only one on the next group buy.
Hope this helps
Ed

HEY! Take that to the Sandbox!!!






--DD

One of the four - oh well - I wasn't in a hurry anyway

Interesting that the Richie Ginther 914-4 modified the stock distributor by removing the vacuum canister altogether.

Also removed the FI harness due to Carb conversion.

I thought it might be useful to experiment with vacuum advance, but Mark Henry suggests it might not be useful for my carb and cam set up.
http://www.914world.com/bbs2/index.php?s=&...t&p=2552875

Curve 1 or curve A?

I have a '73 1.7 with factory D-Jet injection. The stock distributor is a Bosch 007. The booklet that comes with the 123Ignition distributor shows two choices for that distributor: 1 and A. If I'm reading the booklet right, curve 1 is vacuum advance and curve 2 is vacuum retard. Which is the correct curve to choose on the distributor: 1 or A?

I think curve 1 (vacuum advance) is the correct one, but thought I should double-check just to be safe.

Thanks!

1 and use the advance port for the dizzy.

Thanks for the confirmation.

As for the second part, I'm guessing you mean to make sure to connect the vacuum port on the throttle body to the vacuum port on the distributor? If so, already done. A vacuum advance (or retard) doesn't work very well without a vacuum signal.

Yes and that you have the advance port from the TB to the dizzy port. There are two on the 1.7 TB on the 73 , advance and retard.

Think someone posted a nice picture. Don't know right know cause to lazy to look it up.

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.

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 (shoulda taken a pic before disconnecting stuff ).

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.

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

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?

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.

You guys usually connect the blue wire, right?

I believe the blue wire is a ground.

Yes thanks -- got it working this morning.

It's very cool.

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:



Click to view attachment

Has anyone tried this yet?

Just wondering with a programmable dizzy why?

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.

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.

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.

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:

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

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 ...

Almost?

Trying to get the carbs to work seemed the cheaper option in my case... but I'm not sure that will turn out to be true in the long run.

Aftermarket dual throttle body FI $ is going to make your head explode. better make sure the cam in your engine supports fuel injection before you step over the cliff. You can tame the carbs for a lot less.

Kevin, your comment is so true, and it's only for a lack of market (I do suppose) that a kit has not been created (to the best of my limited knowledge) for T1&4 engines. When I see some members here struggle to assemble/debug their aftermarket systems, it keeps me from taking the plunge (well, that, and the aforementioned $$ issue). Is there such a thing? I see Micro/Mega,SDI, maybe another out there, but as far as I can tell, there's no true soup to nuts, bolt on plug and play system out there...

I had to pass on the 123 group buy, I'd been wanting to start a thread on the satisfaction quotient for those who purchased them, but likewise, it seems that all bugs have not been worked out as yet.

I'm very happy with mine at this point. My "bugs" were primarily from confusion about which advance curve to select. This was partly because my D-Jet setup was a little cobbled together previously (my original dizzy wasn't correct for my car, which I didn't even know at the time). I wouldn't hesitate to recommend it for someone who's looking at this product for their teener...

Best replacement for the oem dizzy. I've been running mine well over a year now and its flawless. D-Jet 2056. Late model

I haven't heard of any bugs with it. I'm pretty excited about its advantages over the 009 it replaced in my car.

Michael, I wasn't inferring bugs with the units themselves, just figuring out what curves to use. The Bluetooth is an awesome setup.

Are you satisfied with it's performance? I've got a 205A (I believe) dizzy and I'm sure it's the last foible in my tuning process...

FWIW. That '205' can be misleading. Looking at the handy AA catalog, if your complete # is 039 905 '205A' that is for a 2.0 engine. Djet. A better dist for carbs is 022 905 205AB. Ljet.

After running mine for awhile I noticed a few things. 2.0 FI. Car used to stumble when cold starting. It would start, start to increase rpm, hiccup and would stall if I did not goose the throttle a bit. Now it does not do that at all.

Idle seems a bit higher (I have yet to actually set the timing as it runs so good I am just going with it till I get a little more time to play around). I will likely adjust idle down a bit for now and really set it in summer when it 100+ again. In the past when at top of the heat range it would drop the idle very low and want to stall. Which meant idle at cold start was pretty high to over adjust for that. I suspect that will go away once all dialed in now too.

Pulls very good. Pulls higher into the rpm range with less effort.

So far very happy.

No bugs.....no points....no problems so far....I have driven the snot out of my car since I have installed it....even it over 100 degree temps. My car is bone stock D.jet.

Wish I put it on the dyno before and after...but mine seems to pull faster as well into the higher rpm range.

Are the 123 internals as delicate as the pertronix and like setups or the even the
Mallorys?

They look more robust to me....I don.t know about Mallory.

Maybe I should say forgiving.

You mean like leaving the key on due to Alheimers forgiving to see if the electeonics burns up?

Haven.t developed it yet. Just in case I kept thenstock dizzy in tje car for now.

I don't think the 123 has a burn up problem if you leave the key on with out the engine running like the Pertronix and such. They make no mention of this anywhere.

I'll have to check on that Kevin. I am running Ljet on a 2056 with a 9550 cam. I would like, no, really like to eliminate the pinging under hard acceleration at higher rpms.

This way, I could completely put my foot in it whenever...