I'm going nuts trying to figure out how to hook up the vacuum lines going to the transmission. The car shifts alright, but it's rough. I think I can get it better, though I'm pretty confused by all the modulators, orifices and switchover valves.

The car is an '81 240D with a 5 cylinder motor from an older '79 300D non-turbo. The transmission is an automatic from the 240. The transmission doesn't have any linkages going to it, only a single vacuum line that goes to the modulator. The vacuum pump pulls a solid 20" of vacuum. My current setup is this:

Booster Line -> White Piston Duder on The valve Cover -> Transmission

It drops the vacuum from 20" to 0" when I push on the accelerator. I believe it should start out more at 15", but I'm not sure how to make it do that. Do I need restrictive orifices for that?

Also, what's the bell housing thing on the top of my injection pump? It has a hose barb on there, but it doesn't seem to do anything. I think this should be an ALDA if this was a turbo motor, but it isn't. What's the deal?


Vacuum Modulator by Christian Bryan, on Flickr


Mystery Component by Christian Bryan, on Flickr