123 R-V-IE Distributor vacuum question, Stock D-Jet 1.7L in '72 914-4 Options

[Stev914]

Greetings 914 Worlders:

I'm happy to be asking this question when my car is running GREAT. I'm just really trying to understand how the engine works, and I am puzzled by this.

Q. How does the 123 R-V-IE work with one vacuum line when the stock distributor has two (advance & retard)?

Longer story:

My local mechanic recently replaced my stock distributor with the 123 R-V-IE and adjusted the settings. The engine is mostly stock and has the original D-Jet. It's driving great. I note that there is a single vacuum line into the distributor (I assume this is vacuum advance). The other green hose (I'm assuming this is the retard) is fitted with a plug. Car runs great.

I have my old distributor, which has the advance and retard connections, exactly like you see in this video tour by George Hussey:

https://youtu.be/ioJ1yYU5MrM?si=sEvnLv0Z_cDd_h1s&t=220

Again, the vacuum retard hose in my car is just fitted with a plug now. I am assuming that's not a problem, but I am still wondering how the 123 R-V-IE is meant to integrate into the vacuum system. Here's a great illustration I found here on this forum posted by Jeff Bowlsby:



Sorry for the very newbie question.

Steve
1972 914-4

[emerygt350]

I am not sure about Bluetooth versions, mine is the non-bluetooth, but I have found you should only run it with advance off ported vacuum (port on the tb pointing towards the front of the car) and not with retard (port facing the rear of the car). You can only choose retard or advance with the 123, not both.

The original design was very clever and would do interesting things as the two vacuum sources worked against each other in part throttle situations, which is almost all of your cruising. In the 123 I found the retard was very much just on or off and often at the wrong times.

So... If it's hooked up correctly and just giving you advance I would leave it. If it is hooked up to the retard port on the tb, I would think about plugging it. I am sure someone will chime in with how the Bluetooth uses the signal, if it's any different from the non Bluetooth version.