Distributors

On the left is the 2.0L distributor and on the right a 1.8L knock sensor distributor. In set are the gears from a 2.0L and a 1.8L note the different diameters. Notice also, the difference in the diameters of the distributor bodies where they meet the engine block. Fitting a 1.8L distributor is a fairly simple task an adapter ring is require to fit the smaller 1.8L distributor into the ABA block. Adapter rings are available from various sources, by mail order, including Fast Forward Autobahn Sport Tuning in Canada and Techonics Tuning in the U.S. Here's a picture of a shop made adapter ring

The gears are interchangable, the pin holding the gears in place is pressed in place considerable force is required, but they can be knocked out with a hammer and punch and the gears swapped, use a new roll pin to secure the gear. Volkswagen doesn't sell the gears separately, if you don't have the distributor from your ABA block Fast Forward sells the gears as part of there 2.0L installation kit or you can get a distributor from a wrecker.

I chose to upgrade my ignition system to a knock sensor system in order to take full advantage of the higher compression engine. I got my knock sensor ignition system off a 1986 Jetta Carat. If you chose the knock sensor route, you has one more option regarding the distributor. There is an Audi 2.0L distributor (I don't know the year or model but it is part # 053 905 205A) which will fit into the ABA without modification and is compatible with the knock sensor system just use the Hall sensor that came with your system. Fitting the system to your car requires careful studying of wiring diagrams of the your car and the knock sensor system are necessary so that you can make the required modifications to your wiring harness.David's Volkswagen Page contains a wiring diagram for a knock sensor installation for a car with basic CIS fuel injection.If you chose to install a knock sensor system you will need the following.

In the years that have past since I first did this swap, I've learned that it's quite easy to convert the ABA's distributor into one that's compatible with the knock sensor ignition thus eliminating the need for adapters or swapping of gears. To do this, remove the trigger wheel and hall sensor unit from the ABA's distributor and simply replace them with the one's out of the knock sensor system's distributor, just be sure to install the trigger wheel so that it's orientation with respect to the rotor doesn't change. Here's a VW Vortex thread on this topic. I've had enough feedback from people that have done this sucessfully that I now recommend this method over the TT style adapter ring. It should be noted that this method works for any ignition system that requires a locked distributor like CIS-e knock sensor ignition systems that I used in my car, VW digifant ignition systems as well as any one of several aftermarket engine (or ignition) management systems. Peoplpe keep asking me about this so I've added a page detailing the procedure ABA Distributor Conversion Page

It's also recently been brought to my attention that Techtonics now sells both the gear and the adapter ring either separately or as a set.

Here's some other stuff I've recently found more detail on. If you are in a situation where using a 2.0L distributor gear is not practical, it is possible is modify a 1.8L intermediate shaft so that you can run with a 1.8L distributor gear. The gear on the stock gear is too big and too wide to clear the #4 connecting rod journal. The intermediate shaft can be put in a metal turning lathe and the gear narrowed and chamfered to gain the necessary clearance and the eccentric (a relic left over from the old carbureter days) is also removed. Below are a comparison photos of the stock and modified intermediate shafts.