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Overhauling a Bosch distributor

Bosch distributors are found on many cars and are generally very reliable.

But after high mileage, you may find that the engine isn’t running quite as it should.

If the rest of the fuel and ignition system is well-tuned, But the car doesn’t accelerate cleanly, the problem may lie in the distributor advance mechanism.

Checking and freeing the mechanism is the only work you can do on the Bosch distributor as spare parts are not available.

If there is wear in the distributor shaft bearings, a new unit is the only solution.

The design is conventional with the contact breaker points mounted on a movable plate, Which in turn sits on a fixed baseplate.

The vacuum advance unit is attached by screws to the side of the distributor and Connects to a small post on the upper movable plate by a link rod and circlip.

Table of Contents

Inside a Bosch distributor

The Bosch distributor is fairly conventional inside, With the contact breaker assembly and mechanical advance mechanism, All housed inside the distributor body.

The unit differs from many other distributors in that the Condenser is mounted on the outside of the unit.
If your ignition system is fitted with a ballast resistor, this may also be mounted on the distributor next to the condenser.

Replacing parts

While it is possible to dismantle the Bosch unit for inspection, Many parts, such as the mechanical advance weight mechanism (Also called the bob weights) and the baseplates,

It cannot be bought as individual replacements.

To save buying a new or exchange unit, It is worth trying to get a second-hand one from a scrapyard and Either using the parts you need from this or fitting the unit as a complete replacement.

You can, however, renew the points, condenser, Drive gear and vacuum advance unit.


You should first disconnect the battery by Removing one of the leads to avoid any possibility of a short circuit.

Then remove the distributor from the engine.

Remove the points and condenser.

Now you are ready to strip down the distributor.

Dismantling a Bosch distributor


Ekster EU

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