Published 2007
Excellent Trouble Shooting Guide by Gary Boone
Before consuming your valuable time performing any work on your distributor, you should remove the cap and push on the rotor side to side to ensure there's not excessive wear in the distributor bushings. If you have more than 1/8" side to side movement, your distributor has served its useful life. Give it a decent burial (or hang it on your garage wall for a keepsake) and get another one.
For the standard points and Pertronix equipped distributor, the procedure is the same. Unless you're certain you have a non-smog advance cam in your distributor, start out by finding out. Because if yours is smog, I suggest you obtain the non-smog parts to convert it before you start the work. You can determine whether your distributor is smog or non-smog curved by the steps outlined below. The smog is a 17.5, which produces 35 degrees of advance, which is bad. The non-smog is 7.5, which produces 15 degrees of advance, which is what you want.
You can look at the distributor cam to determine what number is stamped on it . This requires removing the distributor cap and the 2 screws on the outside that hold the vacuum controller to the distributor housing. Pull out the vacuum controller (this may require that you gently pry the lever up and off the pin on the breaker plate). Remove the 2 screws holding the breaker plate to the distributor housing (with some distributors, it's the same 2 screws that hold the 2 clips for the cap). Remove the breaker plate. There is no need to remove the points; the timing and points gap won't be disturbed this way. Deep inside you'll see a plate on the bottom of the rotor shaft. If you can read the number 7.5, it is a non-smog advance curve (good). If it is 17.5, it is smog (bad). If you can't read the # because of grease or whatever, the 7.5 plate has radial slots, while the 17.5 has diagonal slots.
OK, now back to work. It's easier to remove the distributor for this. Just remove the screw on the top of the fixing plate (the one you loosen to adjust the timing) and pull the distributor out. Follow the steps above to remove the breaker plate if you haven't already. With the breaker assembly in hand, try to rotate the upper plate back and forth. It may feel notchy because of the wear patterns in the plates where the ball bearings ride. About all you can do short of replacing it is to spray a light lubricant like WD-40 between the plates and help free it up if it's sticking. Trying to disassemble and reassemble is tricky due to the tiny balls. If you have a Solex car, don't worry about the breaker assembly because it doesn't move anyway.
Now before any further disassembly, make note of the relative orientation of the flat on the rotor shaft to the offset of the tang on the drive coupling, which is on the bottom end of the distributor shaft (engages the drive gear in the engine block). You'll want to re-install the rotor shaft in the same orientation when you're done. Now see how your advance mechanism is working by rotating the rotor shaft back and forth while holding the lower shaft from turning. Since you're already inside the distributor, you might as well do some cleaning, inspection, and lubrication.
Ideally, it would be best to remove the lower shaft from of the housing but this will bring challenges beyond what you may want to tackle. If you decide to do this, drill out the aluminum rivet in the tach drive gear with a 1/8" drill bit and replace it later with 1/8" X 3/4" roll pin.
Either way, keep track of locations of parts as they are removed so that you can re-install in the same place. Remove the screw in the top of the rotor shaft and pull it up and off. Then remove the weights and springs. Clean the parts thoroughly. If you soak the parts in a solvent cleaner solution, don't soak the housing unless you remove the lower shaft because it will dissolve the grease in the bushings, which would be a bad thing.
After cleaning the parts, inspect for wear on the weights and springs. Parts I've seen wear on, are the posts the weights rotate on, the pegs on the top of the weights, and the ends of the springs. Replace parts with obvious wear. Apply an EP or synthetic grease to the posts that the weights rotate on, to the slots in the rotor cam, and to the shaft that the rotor shaft rotates on. Re-install the weights and springs by engaging the springs first and then the weights. Apply grease to the bore of the rotor shaft and re-install it. Don't forget the washer under the rotor shaft. You'll have to make sure the rotor shaft's orientation is such that the weight with the light spring engages the side of the advance cam with the 7.5 number stamped in it. Make sure the pegs on the weights fully engage the slots in the advance cam. Re-install the screw to secure the rotor shaft.
Now check the adjustment of the advance mechanism. There should be enough tension on the light spring to pull the corresponding weight's peg all the way to the inside end of its slot. If it doesn't, bend the prong that the spring hooks on to, outward, but just enough so that the peg fully retracts inward to the end of its slot. This is easier said than done with the lower shaft still installed in the housing.
The weight with the stiff spring should have lots of free rotation. It's spring should not even engage until the other weight is about half way through its travel in its slot. If this needs adjustment, bend its prong the appropriate direction. I usually give the assembly a shot of light lubricant for corrosion protection and to prevent the grease from drying out. Make sure the advance mechanism moves without snagging and returns to the inside of the slots when you stroke it manually.
Complete the remaining assembly in reverse order and re-install the distributor. Then reset the timing and go.
For the EI distributor, the procedure is about the same. You shouldn't have to make any adjustments though. Don't soak the breaker assembly in solvent because it will ruin the bearing cage. Just a clean and re-grease job. I expect the time between required maintenance intervals is much longer because I use synthetic grease. I'd say every 100,000 miles or 10 years, which ever comes first.