912E distributor

[silver912e]

Does anyone understand the two vacuum fittings on the stock 912E distributor? .

My engine was not running when I got my car, and neither fitting was hooked up. How did the cars come from the factory, and where did the hoses from the distributor run?

Thanks.

[craign]

Pure guess here but I would say those are vacuum advance lines that should connect somewhere near the carbs.

Unless the PO removed that function by installing a mechanical advance dizzy (then you wouldn't have vauum lines would you). You might look for a couple of ports near the carb bases that look like they have been blanked off with screws or something like that.

Craign

[Hoffman912]

912E has fuel injection, not carbs...

[eki912]

On my 912E , the right hose goes directly to "throttle valve housing" or what ever it is.... the one where accelerator wire goes to !!! To the visible side , or front side.

The left hose goes to a "device" , at the rear of my engine.Then continuing from there to the other ( rear) side of this throttle valve body thing.

This device of mine is something that I havent seen in any other 912E. Has got something to do with AC , as wire from it goes to AC and another wire to ground. Most likely it is somekind of AC cut oot safety device.

So if I take that out , connect the hose ,it goes straight to the rear of throttle body ! Right hose to front side , left to the rear side of throttle body ! Atleast in my car...... not necessarily the right way , though !!!!

Erkki

[eki912]

On my copy of a 912E L-Jetronic manual of somekind , it has vacuum hose diagram. On that it is marked, that from distributor one hose goes to that throttle body the other goes to a unit marked EGR.

So I canīt be sure how it should go. You have to wait for the other 912E guys to go under their bonnet.....

Erkki

[WFBowen]

Silver:
First determine which vacuum fitting at the distributor is the advance. If you have a timing light hooked up at idle, suck the vacuum hose for that diaphram and see if the timing advances. Make sure the diaphram holds vacuum. Once you've identified it, hook it up to the vacuum port at the throttle valve housing that's just above the actual throttle butterfly. This is "momentary" vacuum which sucks as the throttle is opened, but quickly goes back down as pressures equalize. If you have all of your smog equipment on, this line (at least on the car I had) joins with a t-fitting with the vacuum line to the EGR cannister, which also uses momentary vacuum. Be sure you're connected to "above throttle" vacuum, not "below" as they're pretty close (vertical plane) to the throttle valve. Also, don't confuse "below" vacuum with "constant" vacuum which is taken from the intake plenum downstream of the throttle valve.

Then there's the confusion with the second line. My car had it hooked up to "below throttle" vacuum for timing retard at idle. I've seen at least two cars (both rock-stock) that had it blocked. To add to the confusion, one manual stated that it was only used on some 914 models and blocked on the 912E, while another showed a diagram with it hooked up like my car. I ended up blocking mine off, and the car ran beautifully with a stable idle and timed dead-on all through the rev range.

Either way, it's the advance that counts. As long as everything jives with a timing light (i.e. momemtary surge of advance along with the steady centrifugal increase) you're okay.

[david c.]

IF you have carbs on your car (a common conversion) you do not want to have that distributor on there in the first place.