2.0 Vac ports and 123 Distributor, Which to use? Options

[Olympic 914]

OK another vacuum hose thread.

Just got my car running again after 4 months down, and during this time I got in on the 123 distributor GB.

My engine is a 2056 with the 2.0 FI and two port throttle body. I have the dizzy set on position #1 which is used for the vacuum advance. and this is the port I have hooked up. (green arrow - A ) and I have blocked off port B



It did run okay but not real enthusiastic, which makes me think I hooked up the wrong vac port on the throttle body. Is port B the advance port?

Previously it had the stock dizzy with both vacuum lines hooked up.

right now it is just static timed at 5 deg btdc using the led built into the 123 dizzy.

what benefits are there to using the vacuum port for advance VS using the retard port and the corresponding setting in the dizzy?

Fortunately I can access the dip switch in the dizzy without removing it. (I think)

Hopefully Beat Navy will wade in on this subject since I think our engines are set up similar.

[BeatNavy]

So my experience is a bit different. I ended up going to curve "B" and using the retard port on the throttle body as the connection to the dizzy. I plugged the advance port (I'm actually using a TB now that already has the advance port blocked off). In your picture, A is retard and B is advance. My setup (MPS, ECU, etc.) most closely matches a '74.

I love these dizzies now, but I was surprised about the amount of 'trial and error' it took to get things working optimally. This is probably mostly due to the fact that my original throttle body may not have been year correct, and the dizzy I was replacing was definitely not. So selecting the correct advance curve was a challenge.

I then timed it like stock - 27 degrees at 3500 RPM with the hose plugged. It's running great.

So, the other thing that threw me off is that this dizzy seems to be very sensitive to idle mixture and idle speed. I was having trouble getting idle to settle down below 1500, and I kept thinking maybe I was too far advanced. But when I would back off of 27 degrees, I wasn't getting the performance I knew it was capable of. Then I started playing with the idle mixture and I was surprised how much idle speed was reacting to changes with the ECU idle mixture knob. Leaning the mixture out one or two clicks on the knob made a significant difference, and now I've got a nice stable idle at ~1000. I did not see this behavior nearly as much as on my previous setup.

When the weather gets a little warmer (and drier (IMG:style_emoticons/default/mad.gif) ) I'd consider "playing" with a different advance curve and putting my old throttle body (with advance port) back on. But right now I'm pretty happy with how it's running (IMG:style_emoticons/default/driving.gif)