This photo shows a wide variety of Bosch distributors and distributor parts--ALL of which were supplied to Saab for their V4 engines. There were at least a dozen DIFFERENT Bosch distributors used on the Saab V4 engine, and while some parts are interchangeable, many are NOT. On the left is a really nasty Bosch/V4 distributor--typical of the way they look when I receive them. Moving to the right, there are 7 different drive gears. To the right of that the MAIN distributor parts---body, main shaft, top shaft. Then, a vacuum control unit [one of a dozen different ones used], a points plate [one of four used], a condensor [one of 10 different ones used], a set of points [one of two used], and a rotor [one of 6 used].The box holds half a dozen different top shafts, then several different movable points plates, and one of two different distributor caps. Finally, there are three different distributor assemblies and two different vacuum control units. I've reconditioned close to 500 Bosch distributors, and I still--occasionally--run onto something I have not seen before!
Here are two Bosch V4 distributors with MAJOR differences. The top unit is what I call a "notch body" distributor. Note the extended casting on the side, near the top of the distributor body. This requires a vacuum control unit with its mount configured for that notch body. The distributor body below it is a "round body" type. Note that the vacuum control unit is assembled with a round mount.
Inside, the fun is just beginning. On the left is a very early internal shaft assembly, on the right one of the later shaft assemblies. Because of the orientation of the rotor notch in the top part relative to the 4 lobes that open the points, these will NOT interchange. To further the fun, the later assembly [on the right] has four different lobe-to-notch arrangements and they will NOT interchange, either. In reconditioning these distributors, it is essential to know what parts are compatible. If you don't, you will probably get the thing all back together again and it simply will not work. Fun stuff, eh?
This shows the parts of the internal shafts. On the left, starting at the top, the lower shaft. On either side are the two mechanical advance weights, with their control springs just below them. At the bottom, the top shaft, with the four lobes that open the points, and the notch for the rotor. On the right, the assembled shaft. I control--and can tailor--the mechanical advance curve of the distributor, by changing the advance SPRINGS. I plot the actual curve by running the distributor on the SUN distributor machine, noting the degrees of advance at various readings through the useable RPM range. Sometimes a lot of springs get changed before I'm satisfied with the curve.
Virtually ALL the distributors I receive must have a bushing installed at the bottom of the distributor body. I use a special tool to hold the distributor body so I can drill it in the lathe for the brass bushing. In this picture the bushing has been installed and this setup is for reaming the bushing to the correct inside diameter. This is a fairly delicate process, to get JUST the right I.D. for the shaft, plus just the right clearance. Well....after bushing close to 500 distributors, I DO have that process figured out.
What makes YOUR V4 distributor a candidate for reconditioning? Uneven idle, poor performance, excess fuel consumption, hard starting are a few symptoms. Remember---these gesparkers are 40+ years old! Many Saab V4 owners are amazed at how much better their 40+ year old Saab runs with just a properly reconditioned distributor installed. How's yours running?
City Car Design
5 years ago