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.

[Rob-O]

Beyond all the hooking up of vacuum lines, the change in TB could be because it fits and/or because the Vanagon TB’s had a larger TB plate compared to the 1.8L TB. I don’t know the years specifically but I’ll bet @clayperrine does.

[wonkipop]

Beyond all the hooking up of vacuum lines, the change in TB could be because it fits and/or because the Vanagon TB’s had a larger TB plate compared to the 1.8L TB. I don’t know the years specifically but I’ll bet @clayperrine does.

yes - often done mod.

esp since the original 914 L Jet throttle bodies wore out and leaked air as well as wearing in a groove in the bore of the t/b where it rested at closed position prematurely - requiring t/b replacement anyway.

-------

the double vacuum can set up on the distributor was always a curious thing to me being down here in aus. any AC VW i ever had experience with from the late 60s and early 70s only had a single can distributor- and it was a vac advance can.
these were of course all carb VWs not EFI. either twin carb type 3 or single carb type 1. the vac advance can smoothed out the engine when you were at steady state cruise with partial load changes response smoothed out and increased fuel economy.

i had never seen a double vac can until i got hold of my L jet 914. took me a long time to get my head around them and what they did. its really purely restricted to the US cars at that time and its an emissions solution.

--------

i am still trying to get my head around L jets car and how it was set up by his fathers mechanic. i suspect what he did was set it up to run more or less as a 49 state car with the larger vanagon throttle body for better throttle responce. i think i can see how it was set up to work the retard vacuum can in a slightly unorthodox way but effectively the same as hooking up to the retard can to the retard port on tb. it looks to me like maybe it was connecting the retard can to the plenum and feeding off the same line as the decel valve. there would be no difference then between connecting to the lower port on the throttle body and connecting to the intake plenum.

however normally that t is connecting the fuel pressure regulator and the decel valve t the intake plenum. what i cannot see from his photo is where the fuel pressure regulator vacuum line ended up going and where it connected to on intake plenum.
it must have been connected somewhere to intake plenum somehow. the vac line is there i can see it connecting to the fpr.





another curiousity is that the lower port on L-Jets T/B has been capped. this could have been connected to the retard can on the distributor. but instead the person doing the changes has chosen the T to the decel valve.




---and then you open a can of worms when you look up vanagon throttle bodies.
it may have been 022133067C T/Bs could come with or without lower ports that connected to a retard can on a distributor.




(IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/WTF.gif)

anyway.
assuming the upper port on L-Jets T/B was connected to the advance can on the distributor and assuming the FPR vac hose was connected to the intake plenum in some way i cannot see my conclusion is that his father's car had been EC-Beed so to speak back when the throttle body was replace. in a slightly unorthodox way in terms of where hoses went but nevertheless for all intents and purposes working as per an EC-B rather than the californian set up it originally would have been.