964 Distributor Rebuild

Parts came in while I was out of town for our 964 project which had the internal distributor belt fail. I got cracking early as I knew it would be a long day. First thing to do was the replace the hood and hatch struts so they would stay open. The back of my head is always thankful for new hatch struts.

mmmmm, fresh struts.

After sneaking into the back of the engine bay, both sides get replaced.

Then it was on to rebuilding the distributor. The 964 and 993 use a twin plug ignition system, meaning 12 spark plugs on 6 cylinders (2 per cylinder). One cap/rotor supply spark to 6 plugs, while the other cap and rotor supply spark to the other 6 plugs. They must do this in sync, so that the 2 plugs on each cylinder fire together. This is accomplished via a rubber belt that keeps them in time. When the belt breaks, 6 plugs stop firing, and depending on how the secondary rotor stops, you may have a constant spark on 1 plug. Not good.

First thing to do is set the motor at top dead center on cylinder 1. The primary rotor shows that position.

Then the distributor can be pulled out.

The first thing to do is the drill out the roll pin on the primary gear so we can pull the shaft out the top.

Once you get a good hole started, you can punch it out with a punch and hammer. The ends are mushroomed, so you have to get some space to allow it to crush on itself.

Once it is off, keep the washers with the gear in the correct orientation until reassembly.

Then remove the electrical connector.

And you can pull the primary shaft out of the distributor.

Looking down the bearing shaft.

Next the new belt needs to be installed. I don’t mess with the secondary shaft at all, but rather knock out a roll pin in the housing, pivot it so I can get the new belt in, and reassemble.

Then drop your drive gear and washers into the reassembled housing and start to time the gears so both are firing at TDC on #1.

A paint mark on the gear helps with the timing.

And the shaft reassembled and timed correctly. Now the two rotors will spin together.

Then it was off to replace the plugs and reseal the valve covers. With the secondary plugs not firing due to the broken belt, it was best to go in and replace them all. A 964….off comes the catalytic converter and secondary muffler.

Then you can see the plugs and valve covers.

Valve cover off to replace the gaskets.

After that was done, I headed to the top of the engine to replace a leaking oil thermostat seal, the fuel filter, and the air filter.

I dunno, the oil thermostat is back there somewhere, lol.

And the housing out with the seal that is hard and leaking.

And there you go. There is a lot of detail and effort in the distributor rebuild, but you get the basic idea.

964993Distributor Belt ReplacementPorsche

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August 15, 2011 at 10:12 PM

Cool project, nice job Karl!

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