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Late Ford 8N (50-52)


Just in case you are worried about removing and replacing the side distributor (and getting it back in the right way), the procedure is no different than most other antique engines with a distributor. This is my simplified step-by-step:
1 - Park tractor where it won't have to be moved while the distributor is out.
2 - Clean entire area around the base of distributor.
3 - Remove distributor cap and carefully mark current position of distributor body and rotor. A Sharpie marker or squirt of spray paint can be used to mark how distributor was aligned on the engine block (Take Pictures Too).
4 - Leave coil wire and spark plug wires connected to cap or mark where each wire was.
5 - Disconnect small coil wire connected to points.
6 - Remove bolt and distributor clamp bracket.
7 - During the next step watch rotor to see which way it turns.
8 - Rotate distributor housing slightly back and forth while pulling it out of the engine.
9 - The rotor is now pointing a slightly different direction.
10 - Mark that location too (Take Another Picture).
11 - Carefully Stuff a rag in the hole the distributor came out of.
12 - Do not turn or crank engine while distributor is out.
13 - Do whatever distributor service is needed, or set up points and condenser in a new distributor.
14 - Set rotor button at last observed position.
15 - Remove rag from hole in engine (sorry that should be obvious), grin.
16 - Slide distributor into place making sure rotor and distributor body end up in exactly the same orientation they were when we started. May have to pull out and try this a few times to get the right tooth engaged on the distributor gear.
17 - Replace distributor adjuster and bolt. Double check rotor and distributor body position.
18 - Reconnect small coil wire, and replace distributor cap.
19 - Crank engine and reset timing if necessary. If the point gap was set correctly, and distributor replaced in same orientation, timing will be exactly where it was when distributor was removed.

If the engine should get turned for any reason while the distributor is out, tar and feather the person who "helped" you. OK, we know what really happened. I've done it. We enthusiastically start taking something apart, then realize we don't know for sure how it should go back together. Oopsie! Replacing the distributor, when the correct position of body and rotor are unknown, is more difficult, but not really a problem. Some mechanics prefer to do it this way every time. The extra steps require turning the engine so No.1 (front) cylinder is at top dead center, with both valves closed. Easy with head off, but can also be done with just the No.1 spark plug out. When No.1 starts going up on the compression stroke, air will be pushed out that spark plug hole. Stop when piston is at the top. Locate timing marks on flywheel, they shoudl be in sight. Turn engine slightly to align the correct timing mark for 4 degrees before top dead center. Install the distributor in the engine so the rotor ends up pointing towards where the No.1 plug wire goes in the distributor cap. Set initial timing by turning distributor until the points are just about to open. Lock it in place with the hold-down bolt.

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This is what the side distributor looks like off the tractor. This particular one is a used original pulled from a non-running tractor.

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Remove the cap and the first thing I see is a damaged dust cover. That big black hole right above my hand shouldn't be there. Put that on the list of parts I'm going to need. The rotor button looks brand new. It is very common to find new parts in non-running tractors. Notice the insulator pass-through bushing on the right side in this photo.

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Notice the gear drive on the end of the shaft. If it looks worn, plan on replacing it. There is a collar riveted im place just under the housing. The collar should allow the distributor shaft to turn free without moving up and down in the housing. The gear and collar are held in place with rivets. Both rivets must be removed to get the shaft out of the housing. This one is so dirty, I was planning to take it completely apart.

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Pull off the rotor and dust cover to get at the points and condenser. Rust and dirt inside are not good. Now is a good time to set the points on a lobe (open), then attempt to move the shaft side-to side, while watching the point gap. Basically, any slop equals your margin-of-error when setting the points. This one definitely needs a new bushing. I've also spotted another problem. The pass-thru coil wire connects to the points with a flat piece of copper. The copper strip in this one is in bad shape.

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Remove the points and condenser, then remove two screws and carefully pry the plate out. If it's rusty like this one, you may want to soak it in ATF or toss it in an electrolysis tank for a couple of hours. Once the top plate is out, it's time to go after those rivets on the drive gear and bushing. They are brass, so I simply peel the head off with a sharp chisel and drive them out. You could use a center punch and drill bit to take the head off. Just left of the condenser in this photo is the broken piece of copper that should have been connecting the coil wire stud to the points. You could buy a new copper connector for about $4. The pass-thru bushing assembly is only a little more than that. All of these small parts can also be made from scratch, but I have a better solution.

This coil wire connection does not pass the KISS principal (Keep It Simple Stupid). There are several ways the insulator and copper strip can fail. Why not toss all the tinker-toy parts in the trash and pass the wire from the coil thru a rubber bushing and connect directly to the points? OK, that isn't original, but better than original is the way I choose to go. Whatever you do, make sure the connection from the coil to the points does not touch metal anywhere between the two.

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Ok, rivets are out and here are all the parts arranged how they came off. This is an excellent photo to keep handy when it's time to put this back together. One photo can answer lots of questions. Compare what came apart to the photo in the parts manual. In this case, there is a part missing. There should have been a thrust washer on the shaft when it came out of the distributor. The thrust washer goes just above the shaft bushing.

The advance weights on this one are in excellent shape, but that shaft looks bad. Hopefuly it will clean up ok, a new shaft assembly runs about $45. I'll try to clean and re-use this one. The bushing is pressed into the housing and appears to be impossible to remove even with the shaft out. One way to remove the old bushing is to run a tap in it, thread a bolt into the new threads, then knock the bolt and bushing out with a punch.

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These are the same parts after a thorough cleaning. The rusty parts spent about 4 hours in my electrolysis tank. That took care of the rust. If you want to know how electrolysis works go HERE. The distributor shaft cleaned up OK. It's not great, but this isn't an Indy race car either. Don't forget to clean out the oil groove. I now have a complete list of replacement parts needed. The distributor housing is cast aluminum. Usually my choice is to polish cast aluminum parts with a buffing wheel. Steel parts can be powder-coated or primed and painted. The finish may affect how some parts fit if they were originally unfinished. Once I'm happy with the appearance, these parts will be set aside until I have everything needed to put it back together. That is why I take pictures. It might be a month before I come back to a project.

UPDATE - 3 Weeks Later

Just for this rebuild, the insulator is being rebuilt, and a new copper strip cut from a piece of scrap.

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It's much easier to drill holes if thin stuff is clamped between two pieces of heavire scrap material. Drill two holes before cutting the strip.

The following photo is a new replacement plastic dust cover (LEFT) next to an original (RIGHT). They are not the same. Why am I not surprised?

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The original dust cover fits down inside the edge of the distributor body, so the tang on the distributor cap can engage the slots on the dust cover and housing. This locks everything together in the right place. The replacement dust cover sits on top of the housing. It jacks the distributor cap up and prevents it from locking to the housing. It would be better to delete the dust cover than trying to use this one.

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Here is the completed distributor. The green insulator for the coil wire is a new one made from a scrap plastic dowel that happened to be the correct diameter. The old one looked good but was cracked. Rebuilding the tinker-toy bolt, insulators, and copper strip was only done for this rebuild, so the originality police don't come after me. It is simpler (and much better) to use a grommet and connect the coil wire directly to the points.

Here's another side distributor rebuilt a few years later.

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This is a 12 volt electronic version. The assumption is, next time the distributor needs to be swapped on the '52, the price of a 6 volt battery will force me to convert to 12 volts. Going electronic at the same time will do away with the poor quality replacement points problem. A set of points can last 5-10 years and cost a lot less than one electronic ignition conversion, but if the only points available are junk, the electronic module may be the better choice.


The "side mount" or "angle mount" tractor engine blocks have a timing hole on the right side near the back where the clutch/flywheel are located. It is covered by a teardrop shaped metal plate with one screw in the small end. It may be cleverly concealed under a thick layer of grease and dirt. The timing marks are stamped on the flywheel. There are no timing marks anywhere around the front of the engine (This is true for the TRACTOR engine. However, some of the engines found in tractors are not tractor engines. This same basic Ford engine was used in trucks, stationary applications like pumps, generators, and a bunch of other vehicles and equipment. It was a very popular and inexpensive design. Almost anything goes if you cannot read the serial number. Tractor serial numbers for 8N engines always started with the "8N" designation.

I might use a timing light to see how close my 1952 8N engine is to factory settings, but I prefer to set my final timing by trial and error the same way I dial in a front distributor engine that has no provision for a timing light. If the engine runs at all, mark where the distributor is, loosen the clamp, turn it about 1/8" and tighten the clamp. See if it starts and runs better. If so, try another 1/8" in the same direction. Likewise, if it gets worse, turn the distributor the other way. When you get close, try just 1/16" each way. You can fairly quickly dial in the sweet spot for your engine in this manner. Too much advance will start getting hard to start and will run hotter. Too much retarded and power will quickly drop off.

You probably don't have a temp gauge, but keep an eye on the exhaust manifold. It should come close to red, maybe a dull red with a good load on the engine for a few minutes. Glowing cherry red is too hot. Either too much advance, too lean on the fuel mixture, or both.


If you can't buy new plastic parts, make them yourself.

When this was written, there was no way to buy a new dust cover for the 8N side distributor (still not available Sep 2018). When new parts are not available, options are to try and buy used parts, repair the old part, or make a new one. The dust cover is plastic. There are two-part plastics available that can be used to mold just about anything. I had never done it, so I didn't have a clue what was needed, or if the materials are safe to use at home.

Search for "Plastic Molding" on the web and become an instant expert. Yes there are safe materials available (as long as you don't eat the stuff). There were even a few complete molding kits. After reading the reviews, it seemed as though the kits just packaged a bunch of things I didn't need, for more money than I wanted to spend. In hindsight, it might have been better to get a small starter kit (with instructions "GASP").

In order to mold a plastic part, first we need to make a mold. There are lots of choices for a mold. We could carve a mold out of wood, or mold one out of clay. It would be best if we had a perfect original to make the mold. Yea Right! After taking dust covers out of all my in-use and spare distributors, they are all broken in some way. Pick the best one.

The dust cover is thin, so the best mold would be something flexible that could be peeled back to release the part. Easy Mold Silicone Putty by Castin' Craft is a 2-part silicone material. We will need a container for the mold. This container can be anything sturdy enough to hold the material while we press the part into it. If the container is just slightly larger than our part, we will use less material to make the mold. We happened to be in the Dollar Store and found some small plastic bowls the right shape, and slightly larger than the dust cover, perfect!

the silicone material is worked like soft clay, or bread dough. Two parts are contrasting colors. Take equal amounts of each color, fold and mash them together, until the two colors blend into one even color. From that point, we have a few minutes to put the ball of goo in our container and press our part into the mold.

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This is the first half of the mold. Do not remove the original part until we finish making the other half of the mold.

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The second half of the mold is made right on top of the bottom, with the original part still inside. What you see in the photo is one of the new replacement dust covers that didn't fit jammed into the top to provide a level base to set something heavy while the mold is being used. Some types of curing plastic may try to push the mold apart.

Once the second half of the mold has cured, pull the top off, and remove the original part. Put the mold back together and we have a void between the to parts of the mold that is an exact copy of the part we want to make (almost). If the part we used to make the mold was perfect, the mold would be done. When the original part is not perfect, the next step is to trim away material that filled cracks and holes that we do not want to see in our finished parts. Trim carefully! A rotary Dremel tool might work better than a sharp knife. If you want to add raised lettering on your part, just carve it into the mold.

Next we need to decide what type of plastic to use for the finished parts. For some parts the same silicone used for the mold may be OK. The dust cover needs to be more rigid. A 50:50 mix is the most fool proof of any two-part product. Go to http://www.alumilite.com and browse their products. They will have something that will work. In this case, the best material seemed to be a Urethane good for up to 300 degrees. Hope it never gets that hot inside my distributor! This is a 2-part liquid that should stay liquid long enough to pour into the mold. Pay attention to cure time. Some products may react faster than we can get them into a mold. In this case, the plastic has to remain liquid long enough to be poured into the mold, and then the mold top has to be placed in a way that does not trap bubbles. It might be possible to drill a couple holes to let air out. I didn't want to try drilling holes in silicone and holes would create pointy "things" on my finished part that would have to be cut or ground off.

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This is what happens when a bubble is trapped in the mold. The material that squeezed out around the edge proves plenty of plastic was used. This was not my first attempt. The first batch of plastic sterted to get hard while being mixed! This new dust cover looked too good to give up on. I left it in the mold and mixed a tiny batch of plastic to fill the void. Poured it in, replaced the top, and it worked!

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Tried again a few days later, and made a good dust cover on the first try! They come out of the mold nearly ready to use, they only need a little sanding around the edge to fit and work fine. Now that I have a working mold, I can make a new dust cover whenever I need one. I might even go crazy and add some black color pigment one day.

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