Eager Beaver 160s McCulloch chain saw

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Butch57

Butch57

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I am new to this forum but I join to pick someones brain. I have a McCulloch Eager Beaver 160s chain saw. The ignition coil has 3 wires . One goes to the spark plug, one goes to the kill switch, the third wire is the confusing one. Two torq head screws hold the coil to the motor. Both screws have plastic tubes going thru the coil to keep the screw from grounding out, also there are two micarta washers that set under the screw heads to keep them also from grounding out . There are three washers that set on the micarta washers to keep the screws from damaging the micarta washers. Now the third wire has a small round electrical fitting that the screw goes thru and then the screw is tightened. Here's what doesn't make sense to me, if the screws set on micarta washers and the plastic tubes keep them from grounding out on the coil, but a screw has the electrical fitting and it is grounded out on the motor , how does that work ? Any one who can help me understand it would be most appreciated.
 

JP56

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I am not positive about your saw, but I have seen those wires on other saws, where the loop goes over a small screw to someplace on the engine near the coil. If that is the case with your's you should see a small threaded screw hole somewhere on the engine.
 
Old2stroke

Old2stroke

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Those tubes are confusing, it has been suggested that they are there for thermal isolation to keep the coil a little cooler. I don't really buy this theory as it seems to be an attempt to keep the laminated core of the coil from grounding to the saw body, even the third screw mounting the carb has the tube on it. The person who designed this had something serious in mind but I don't know what it was, never have seen it on a different ignition. In any case, one end of the primary of the coil HAS to be grounded to the same metal that the spark plug is screwed into so one of those wires goes under the head of one of the coil mount screws and MUST be in contact with the screw head. The other wire connects the other end of the primary to the points under the flywheel, it goes under the same screw that connects the capacitor to the fitting under the flywheel. I have been tempted to leave one of those tubes out to see if it makes any difference but if it does, a lot of work just to put the damn thing back in.
 
Old2stroke

Old2stroke

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Just went back and reread your post. If your saw has a kill switch that a wire connects to, then it is different from what I described, probably you have a newer version with an electronic ignition module ( is there any visible capacitor near the flywheel ?). If it is electronic (no points or capacitor) then that third wire has to go under the screw head of one of the coil mount screws to connect the primary of the coil to ground.
 
heimannm
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The tubes and washers are for thermal insulation only. The coil must be grounded via the screw in order for the saw to operate.

There were a very few Mini Mac models equipped with an electronic ignition coil rather than the more conventional points/condenser system. The 160S models were one of the few that might have been equipped with the electronic coil.

The flywheels are the same for the points or electronic saws but the crankshafts are different. I don't know if the timing was different by the placement of the key way but the IPL's are adamant that the crankshaft for the electronic ignition units were different from the points ignition saws.

Mark
 
Butch57

Butch57

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The tubes and washers are for thermal insulation only. The coil must be grounded via the screw in order for the saw to operate.

There were a very few Mini Mac models equipped with an electronic ignition coil rather than the more conventional points/condenser system. The 160S models were one of the few that might have been equipped with the electronic coil.

The flywheels are the same for the points or electronic saws but the crankshafts are different. I don't know if the timing was different by the placement of the key way but the IPL's are adamant that the crankshaft for the electronic ignition units were different from the points ignition saws.

Mark
Mark what are all the numbers and letters representing at the end of your note ? Also in the parts manual it lists the p/n 84957 coil is used on a 11 level Eager Beaver. This unit doesn't have points or a condensor. On a 12, 17, and 18 level Eager Beaver model uses 217031 electronic ignition assembly. And as you said the type of crank shaft is different for each. The wire that clips on the coil goes to the kill switch. Thanks for the input.
 
MacAttack

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I think that wire should be grounded to the chassis.

For what it's worth, I have an Eager Beaver trimmer with no spark because the module is dead. You could simply have a dead ignition module.
 
Butch57

Butch57

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This 160S Eager Beaver doesn't have points, thus no condensor, just an ignition coil. I take it what you call and ignition module is what I have called the ignition coil. I don't think the coil is any good, will take it to a dealer who once had a franchise with McCulloch and he will check it out.
 
MacAttack

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This 160S Eager Beaver doesn't have points, thus no condensor, just an ignition coil. I take it what you call and ignition module is what I have called the ignition coil. I don't think the coil is any good, will take it to a dealer who once had a franchise with McCulloch and he will check it out.
Yep, we're talking about the same thing, and you're most likely correct.
 
Butch57

Butch57

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The fella that checked out the coil didn't get a spark either. Thus # 2 coil down. I'm curious about something. How can a person look for that coil possibly used on other equipment and not a chain saw.
Also if it was made in Sweden then how could a person get a hold of the original mfgr.
 
Old2stroke

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Trying to find a coil that will match can be very time consuming but possible. Critical things are the coil has to be from an engine with the same size flywheel that has only one set of magnets that are the same polarity as your saw and the "footprint" of the two ends of the laminated core have to match your coil. Then you have to fabricate some method of mounting it so that the ends of the new coil are in the same spot as the old one. After all this, the advance curve may not be the same and you have to be prepared to modify the timing as well.
 
Butch57

Butch57

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The idea was to replace the coil on the core. The ends of the old core would be the match for the flywheel. The idea of replacing the core and it's position on the core is what is the concept. The only thing I would have to match is the core beings it is from a ignition coil that was the same size and worked with
a saw that didn't use points and condenser. I know it would be easier to wait and find a used one , but it seems they are all in demand and none are available. It's just an idea. Also how would one go about contacting the Sweden mfgr ?
 
Old2stroke

Old2stroke

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Replacing the coil on the core is great if you can find a coil that will come off the core. Many newer coils are epoxy potted on the core with the ground wire attached internally to the core and these will NOT come off without destroying them.
 

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