First, check out tip # 39. Timing info is in the I&T FO4 manual. A 70 year old tractor w/ a 70 year old owner needs the manuals!
Yes, you can set the timing on a front mount distributor.
The first thing you need to check when you get the distributor off the tractor is bushing wear. If the shaft has any sideways movement AT ALL, the bushings must be replaced. (see below)
Next, make sure you are using quality points. I use only Wells, Blue Streak or Echlin brand points (* see below). Check the point gap, .015 on all four lobes. And, don’t forget to lube the rubbing block w/ cam lube; not Vaseline, not bearing grease, but cam lube (** see below).
If you are using quality points and cannot get the gap to pen to .015, chances are you need to replace the bushings.
Now, set the timing. 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!
And finally, do not forget to remove the distributor on an annual basis (more often, depending on use) to check the point gap and re-lube the cam.
* NAPA part numbers:
• Points: FD-6769X
• Condenser: FD-71
• Rotor: FD-104
• Cap: FD-126
** Distributor cam lube:
http://www.napaonline.com/Catalog/Result.aspx?Ntt=ECH+ML1&Ntk=Keyword&Nty=1&Dn=0&D=ECH+ML1&Dk=1&Dp=3&N=0
** Distributor cam lube
http://www.carquest.com/webapp/wcs/stores/servlet/subcategory__10151_-1_10651_11340
*** 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
There are three ways to replace the bushings in a front distributor:
1. Buy new bushings (part numbers 9N12120 front & 18-12132 rear). Press out the old ones, press in the new ones and ream to fit. CAUTION: do not try this unless you have a press & know how to use it. If you break the base, a new one costs $130. If you bend the tower which holds the front bushing, a new plate will cost you $30.
2. Take the new bushings and distributor to your local machine shop.
3. Send the distributor out for bushing installation.
75 Tips