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

[Stev914]

Thank you for those explanations. It's helpful.

The big picture for me is that, while I am semi-handy, I don't know much about engines. I'm still building a mental model of how this thing works.

As I understand it, the R-V-IE model of the 123 dizzy (look at me using new lingo) is the non-Bluetooth version that has both vacuum advance and D-Jet compatibility. The advance curve is set manually by a switch on the distributor itself, as opposed to connecting by USB or Bluetooth (which is just fine by me--my goal here is "set it and forget it").

I'm going to take the winter months to read and theoretically understand how the entire engine works. This site and YouTube are great resources. But asking questions always leads to more questions for me.

Q. Is there a good repair manual or book that breaks down the Type IV 1.7L D-Jet engine well? I'd love some recommendations.

Q. Is there any negative impact of the "retard" hose not being hooked up to the distributor (apart from the distributor not getting retard)? In other words, is this a "break" in the system that denies some other component vacuum retard, or it it just a function of vacuum retard not going somewhere?

Again, sorry for newbie questions. My goal is to read these posts of mine next year, shake my head, and realize how far I have come in my understanding thanks to you all.

Steve
'72 914-4