vacuum hose routing question Options

[L-Jet914]

I was installing my new ignition and FI harnesses today and I decided to look back at the vacuum hose routing diagram on Jeff Bowlsby's website. I knew my vacuum hose routing had been modified by whatever technician worked on my father's 74 914 1.8 years ago. I noticed that they teed the vacuum retard side of the vacuum advance into ported vacuum off of the intake plenum. According to the vacuum routing hose diagram, it's supposed to be connected to the rear port of the throttle body (which only gets vacuum after the throttle plate moves off idle). Would there be any reason the technician did this? I will end up rerouting the vacuum hose to the proper location. I'm just curious as to why it was modified for whatever reason. So would my 74 1.8 be considered a early or late 1.8? According to the late diagram and the throttle body that is in the car, the hose should route to the front port instead of the rear port.
The part number on the throttle body in the car 022133067C which fits either a Super Beetle 75-79, 76-83 Bus, or 83-84 Vanagon (two port t-body). According to the PET on AA's website shows two different throttle bodies 022133062L or 022133062S for California spec 1.8L 914s. The Porsche PET does not list a throttle body part number for the 1.8, only the 1.7 and 2.0s. Curious as to why someone would put the wrong part number throttle body on my 914, though it does have the 3 pin throttle position sensor. Port setup would be indicative of late 74 because the required port (front of throttle body pointing toward front of vehicle) is behind the throttle plate.

[wonkipop]

@L-Jet914

david - that throttle body looks identical to the 74 914 49 states.
yes i would set it up EC-B.

i can't really see from photo of your engine bay exactly where the vac line originally went from advance can to t/b. but it should not T into the intake plenum.

the only line that had a t into the intake plenum in that vicinity was the vac line from the fuel pressure regulator and decel valve which had a t junction and then connected to the intake plenum.

the hose diagrams i linked to give the correct original configurations.
cheers mate. (IMG:style_emoticons/default/beerchug.gif) michael.

[L-Jet914]

@L-Jet914

david - that throttle body looks identical to the 74 914 49 states.
yes i would set it up EC-B.

i can't really see from photo of your engine bay exactly where the vac line originally went from advance can to t/b. but it should not T into the intake plenum.

the only line that had a t into the intake plenum in that vicinity was the vac line from the fuel pressure regulator and decel valve which had a t junction and then connected to the intake plenum.

the hose diagrams i linked to give the correct original configurations.
cheers mate. (IMG:style_emoticons/default/beerchug.gif) michael.

Currently the retard side of the vacuum unit is plumed into an extra T-fitting off of the plenum. The vac advance was connected to the rear port (facing towards the rear of the vehicle) before I disassembled things to install the wiring harnesses. I will connect the hoses as per the EC-B diagram per your recommendations of the engine running cooler at cruise and lower NOx at idle with retard operating only at idle. Thanks again.
Regards,
David