Technical Articles

Changing the points and condensor

The 912E Owner’s Manual recommends that the ignition points be replaced every 15,000 miles. It’s good practice to replace the condenser at the same time. When you replace the points, you then must check and, if necessary, re-set the timing to spec.

TOOLS NEEDED: New set of breaker points; new condenser; a little grease; various flat-tip screwdrivers, including one of those angle screwdrivers; a magnetic screwdriver if you’ve got one; feeler gauge set; dwell/tach meter; strobe timing light; a bottle of white-out; 10mm wrench; an appropriately sized wrench to turn the engine over.

First, remove the distributor cap. You will find that there are two spring clips which hold it on. Insert a screwdriver between each clip and the distributor case, and pry them off the cap. The cap then simply lifts off. Do not remove the spark plug wires from the distributor cap. Just set the whole thing aside as a unit for now. Remove the rotor by pulling it straight up off the distributor shaft. Remove the plastic dust cover by lifting it off the distributor.

Take a moment to observe the inner workings of the distributor. You’ll see inside the distributor a shaft which is a square with rounded edges. Riding on this shaft is a little plastic block attched to a funky looking metal thing with a wire coming from it. That funky metal thing is the points set. Do a little experiment to see how they work. Put the car in neutral and then get your tool to turn the engine over. Use this wrench on the altnernator/generator pulley nut and turn it clockwise. If this merely turns the alternator/generator and not the engine, your drive belt is too loose. Fix this and try again. Turn the engine clockwise with your wrench and observe what happens with the points as the distributor shaft rotates. You will see that the points open when the rubbing block of the points hits the rounded edges of the shaft, and they close when on the flats.

The first thing you are going to do is remove the old points. You will see that there is a screw that holds the points unit to a plate inside the distributor. Loosen and remove this screw. Don’t drop it and don’t lose it! It helps to have a magnetic screwdriver to withdraw the screw from the distributor. Once you’ve done this, unplug the wire from the points from that black plastic plug that it’s connected to. Just pull it straight off.

Now withdraw the points and if they are pitted/excessively worn, toss ’em. If they look good, keep them in your spares stash for an emergency. Next step is to remove the condenser. The condenser is the little metal can that’s screwed on the outside of the distributor. There are two screws holding it on—one that holds the condenser on itself, and another which holds the black plastic plug to the distributor body.

On the Type 4 engine it’s a little tricky. The screw that holds the plug in is not accessible unless you turn the distributor or remove it from the car. Here’s one way of doing it - eyeball how the distributer is oriented in relation to other engine parts, so you can return it to that same general location later. I notice that the vacuum advance biscuit on mine was parallel to the crankcase seam. Get your 10mm wrench and loosen the long nut at the bottom of the distributor that is used for changing the ignition timing. Loosen it until you can turn the distributor by hand. Remove the vacuum connection from the distributor to facilitate turning. If you have fuel injection, unplug the cold start valve. The plug just pulls off.

Now you can rotate the distributor to gain access to the screws. The one that holds the condenser on is fairly easy to get to. Undo that screw but be careful not to drop it. If you do, you will likely have to go fishing with your magnet on a stick. If you don’t have one, go get one! The other screw, that holds the plug in, is trickier. Rotate the distributor until you can get to it. You will probably have to use your angled screwdriver to turn the screw. If you don’t have an angled screwdriver, you will probably have to remove the distributor to change the condenser.

If it turns out you have to or you wish to remove the distributor, refer to the Haynes and/or Bentley manuals for the procedure. Find the nut-on-stud that holds the distributor to the crankcase and remove it. Then lift the distributor straight up out of the crankcase. The distributor will only go back in one way, so as long as you don’t remove the distributor drive gear from inside the crankcase, you’ll be OK.

Now unplug the green wire from the condenser plug from the (-) side of the ignition coil. Pay attention to which terminal it goes on. Now withdraw the whole condenser mess and get out your new one.

NOTE: For optimal performance, only use Bosch ignition parts on your 912E’s engine.

Now, reassembly. On the new condenser, find the plastic plug. You will see a groove in it that the metal plug clip fits into. Fit the plug into the clip and then fit the assembly to the distributor body and start the screw. Try not to drop the screw — it does take some nimble fingers. Once you’ve started the screw, go ahead and tighten it down. Next, you want to install the condenser itself. Type 4 — rotate the distributor as needed. Install the new condenser with the screw to the distributor body. Again, nimble fingers are helpful. Once that is done, run the green wire to the same terminal on the ignition coil you took the old one off. It should be the (-) terminal.

Now you need to install the points. First, take a little dab of grease and smear some on the distributor shaft. The proper grease should come in a little packet with your new points set. A little goes a long way. Now fit the points. You will notice that at the hinge end of the points, there is a protrusion that fits into a hole in the points plate. Make sure that is engaged properly. Then when it is, insert the hold-down screw and tighten it some, but leave it loose to provide for adjustment later. The magnetic-tipped screwdriver really helps with inserting that screw.

Now you want to turn the engine over by hand again. Use your wrench on the alternator/generator pulley to do so. Turn the engine over until the points rubbing block is on one of the high points of the distributor shaft and the points are fully open. Eyeball it really well. Look at it straight on from above and make sure the points are on the high point and are fully open.

When this has been achieved, grab your feeler gauge set in one hand and a flat-blade screwdriver in the other. You are going to adjust the gap between the points. The minimum gap is .016" and the range is .016" to .020".

Pull out the appropriate size of feeler gauge and slide it between the points. Make sure you are doing it straight on. The blade should slide through with slight resistance when the gap is correct. If it needs to be adjusted, grab your flat-blade screwdriver. Look down at the plate the points sit on, toward the tip of the points away from the points hinge. You will see two small nubs on that plate. What you do is insert your screwdriver between these two nubs and use them to lever the points open or closed, depending on your needs. It’s harder to describe than it is to do. So lever the points until the correct gap is achieved, and then tighten down the screw. Check once more and if it is correct, be happy. If it has changed, loosen the screw, adjust the gap, and tighten it again.

Now you are almost there. Rotate the distributor back as close to its original position as you can. Re-attach the vacuum line and plug back in the cold start valve. Now you need to put the distributor back together. Put the plastic dust cover back on, then the rotor. Notice that the distributor shaft has a cutout that fits a protrusion on the rotor. The rotor will only go back on one way. Press the rotor down onto the shaft and then wiggle it a bit while pushing down on it to make sure it is seated properly. Then replace the distributor cap. It is notched on one end as is the distributor body, so the cap will only go on one way.

You may wish at this time to replace the distributor cap and rotor. If so, substitute the new rotor for the old one when you place it on the shaft above. Then orient the new distributor cap correctly regarding the notch. Now transfer the spark plug wires ONE BY ONE to the new distributor cap. Make sure they are all fully seated in the new cap. Fit the cap to the distributor body and then re-engage the spring clips.

Now start the engine. If you rotated the distributor, you may find it running roughly, but it will improve on adjusting the timing.

First attach your tach/dwell meter according to the manufacturer’s instructions. On my digital model, the red (+) cable goes to the (+) terminal on the coil, and the black (-) cable goes to the (-) terminal on the coil. Then I merely turn the knob to “Dwell, 4-cyl” and observe the reading. It should be within the specification set by Porsche. On the 912E, the specification is 47°, plus or minus 3°. So, anywhere from 44° to 50° of dwell is acceptable. If yours is out of range, you need to go back in and adjust the point gap until it is within spec. Making the point gap narrower increases the dwell reading and widening it decreases the reading, since the dwell is the number of degrees of rotation during which the points are closed. Too narrow a point gap can lead to burning of the points, which destroys them, and too wide a gap can lead to misfiring under high rpm and high load conditions.

Once you have done this, you need to time your engine, since changing the point gap changes the ignition timing.

DISCLAIMER: These procedures are presented as guidelines ONLY. They reflect particular jobs that were performed by 912E enthusiasts and are offered here as a guide to others who might need to do the same procedure. No representations as to the accuracy of the information contained here is made. The procedures were written to help other 912E owners. These guidelines should always be used in conjunction with a good set of repair manuals, such as those listed above.