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Setting the Timing

Now we will be setting our timing. That is the ignition timing not to be confused with valve timing that can only be adjusted on a few all out racing engines. What we are doing when we set the timing is determining when the spark ignites the fuel/air mixture in the cylinder. The ideal time is just before the piston reaches the top of the compression stroke. That way the gas has enough time to completely ignite and release it's power to drive the piston down as it moves past top dead center. If the timing is too soon the explosion will try to drive the piston back down as it is coming up. Not good. It can also cause a condition call spark knock, which simply is an uneven burning of the gases. (This can also be cause by low octane fuel) This explosion is not a steady push of power against the piston but more like hitting the walls of the combustion chamber with a hammer. Again not good. If the timing is too late the piston is actually running away from the explosion on its way back down and not fully benefiting from the expansion produced by the combustion. Both too early or too late can cause the engine to run hotter and make it work harder to do its job. The timing can be set while the engine is not running (static) with the exception to the distributor that has two vacuum advance lines that was on the early 70s motors. These are set with a strobe timing light at 5 degrees retarded or after top dead center while at idle. On most engines and most distributors a setting of 7-½ degrees advance or before top dead center seems to be ideal. The procedure goes like this. Bring the engine to top dead center on #1 cylinder.

Take the distributor cap loose. The rotor in the distributor should be pointing to the #1 plug wire at about the 4 o'clock position. There should normally be a little notch in the distributor body near there. It is important that you are on #1 and not #3 because the lobe that opens the points on most VW distributors is retarded a couple of degrees to make #3 run cooler. With the engine at TDC on #1 to set the timing at 7 ½ BTDC you turn the engine back or counter clockwise until the mark at 7 ½ lines up with the split in the case.
Which notch is that? John Muirs book and our Vol.1 video shows many of the pulleys and shows which notch is which but the safest thing to do is to find exact TDC on yours and mark it once and for all.You can do this by pulling the #1 plug and bringing the piston to TDC and past a few degrees so the piston is going down. Now use something to put through the spark plug hole, a dowel or bolt or whatever to touch the top of the piston. (A bolt threaded into an old spark plug makes a good tool for this but is a lot of trouble for a one-time thing.) What ever you use needs to be held tightly so you may need a friend for this. With the piston a little past TDC mark your pulley. Now continue turning the motor over until the piston comes back up again and touches the piston. Mark the pulley again. Now put a mark in between these two marks and you have TDC. About 7/16" to the right is 7 ½ BTDC. Any other setting you can pretty much figure from there. Now that we have the engine at 7 ½ BTDC we loosen the 10mm bolt that holds the distributor.
Attach a12v test light to the connector where the green wire fastens to the coil from the distributor.
Ground the other end anywhere.

Turn on the ignition. Not the starter. Now turn the distributor a few degrees maybe an 1/8 of a turn clockwise and then slowly turn it back counterclockwise until the light just goes on. Perfect!

This is so cool the first time you do it. The timing is set. Now tighten the bolt back up on the distributor and you are done. If the light wants to stay on the points may have a film of dirt or oil on them. Clean them off by sliding a clean piece of paper through them. If the light won't come on the points are grounded. Your wire from the points is probably touching the inside of the distributor. Contrary to what many think the light comes on when the points open not close. You can actually set the timing by listening to or watching for the little cracking of juice through the points as they start to open. Try it! You can see this done in detail in our Vol.1 General Maintenance video available from Bug Me Video.

Rick Higgins and Crew
Bug Me Video, Inc
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