964/993 Twin Distributor Belt Rebuild
One of the most commonly overlooked belts on the 964/993 is the one that you can’t see (other than the 993 PS belt, lol). The twin plug distributors use an internal belt to time both ignition rotors together, allowing the cylinder to fire on both the top and bottom spark plug. If this breaks, the secondary ignition rotor stops spinning, thus no spark to half of the spark plugs. If you are lucky, the rotor stops in a position between two contact points on the distributor cap where it can’t cause any damage. If you aren’t so lucky, it will stop inline with one of the cylinders, allowing a constant spark to that cylinder, which can lead to a very lean condition and internal damage. With the cars being 20 years old, it is a good idea to yank your distributor out and get the belt replaced. We offer this service for $150 if you send us the distributor, or $275 in house.
After some digging, the distributor is removed from this 964 for a rebuild.
Here it is out of the car. The secondary distributor is on the left, and the primary with shaft on the right.
Soft place to work. Mt dew at the ready. Ignition rotors and shields removed.
After drilling out the retaining roll pin at the base of the primary shaft, I removed the shaft from the housing.
Here is the tiny belt that runs the two rotors.
More dis-assembly of the distributor to get the belt in place.
And the new belt in place. There are a lot of little parts and pieces you need to be careful of if you are doing this rebuild.
With some careful timing, the rotors are properly timed together in the correct orientation. After that, installing a new FACTORY copper roll pin at the base of the primary shaft and we install back in the car. The factory pins are cheap, do not settle for a standard roll pin.
Then it was on to another 964…..
After pulling this distributor, I found the belt was previously replaced, so we didn’t go any further. The interesting part was though that the belt had obviously broken and the distributor caps had not been replaced. Here you can see where the secondary ignition rotor stopped when the belt broken and fired a constant spark on this particular cylinder point, burning it up. No wonder the car didn’t run at it’s peak level.