" Ok, I admit it, I hate to take the distributor out and fool w/ it."
It's not that hard to do....especially if you get The Old Hokie's jig.
" Do they get out of time just by running them?"
Yes, they most certainly do.
First, the timing changes whenever you change the point gap.....which occurs as the rubbing block wears down.
The first thing you need to check is bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced.
If you are using quality points and cannot get the gap to pen to .015, chances are you need to replace the bushings.
Get a meter or test light, a 21/64” drill bit (*** see below) & a metal straight edge. Put the distributor face down w/ the condenser on the left & the timing plate lock screw on the bottom. Look at the end of the shaft: it has a narrow side & a wide side. Make sure you can tell the difference. Now, place the drill bit in the bottom mounting hole (this will be your reference point for measuring). Next, place a straight edge on the wide side of the tang on the shaft as shown in fig. FO83 in the picture. Rotate the shaft CCW (as viewed from rotor side OR CW as viewed from back/tang side) until the straight edge is ¼" beyond the outside edge of the drill bit you stuck in the distributor mounting hole. At this distance, the distributor points should start to open (get your meter/light out now & check). If not, loosen the timing plate lock screw and turn to advance or retard the timing (move the plate down to advance timing, up to retard). Remember, each one of those little hash marks represents about 4° of timing. Keep adjusting until you get the proper ¼" setting. (if the plate won’t move, you might need to remove the big C clip to loosen it a bit) As you’re adjusting, eliminate backlash by turning the shaft backwards (CW as viewed from the front) and bring the shaft forward (CCW as viewed from the front) to measure your setting. This ¼" setting will get you static timing at top dead center.
As you can see from the picture, this particular distributor needed to have the timing advanced by about 8° (two hash marks) to achieve the ¼” measurement.
After you set the points & timing, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.
With the distributor still off the tractor, follow these steps:
1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.
2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.
3. Put the coil on the distributor, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!
4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!
*** Rather than the drill bit, a jig made by Dan Allen (The Old Hokie) will make this task quicker & more accurate. http://mysite.verizon.net/oldhokie/windyridge/id11.html
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