4.0 distributor question?

My 88 commanche 4.0s distributor has the usual 6 plugs on top, and one ignition plug in the center.(the engine is newer, it's not the one that came in it. The distrib. is located just to the left of the engine, looking from the front) My question is: There is ONE MORE plug looking opening right next to the iginition plug near the center? What is this for?
It has a hose connected to it, but the end of the hose goes nowhere?
This hose has a hose clamp in it, but it wasn't on very secure?
What's the purpose of the hose? What's this plug opening for?
Any help would be great.

There is usually a cap on that fitting - all it is is a distributor vent. If you replace the cap, you'll find that there is a small "nipple" in between and inboard of a part of HT cable towers, with a cap on it. That's the vent.

If you can get something that fits loosely over that nipple (or just get a new cap that already has the vent cap on it) you can remove the hose and not worry about it.

I was going to read you off for double-posting (we've been getting an awful lot of that lately, for some odd reason...) but you've already made an effort to excuse yourself for doing it, so I shan't.

5-90

So, it has to have a cap with some sort of vent built into it?
Or can I cap it with a rubber cap with a few pin holes.
I guess the hose that was on there was for deep water applications?

Who knows why the hose was on there?

The vent is there because the inside of the distributor communicates directly with the crankcase (witness the proliferation of "Oil in Distrubutor" threads) and any pressure buildup in the crankcase runs the risk of popping the distributor cap off. That's why the vent - it's little more than a pressure relief device.

5-90