1971 Mercury 9.8 ignition wiring impedance

[kazeej]

My dad bought this engine almost new. It didn't get much use, and spent almost its entire life in a shed. It doesn't have more than 50 hours on it.
I decided I would see if I could resurrect it. It has great compression (115 in both cylinders), the carb needed to be cleaned out, and it had spark until I replaced one wire that tied the two (-) connections on the coils together. The wires that run to the coils are badly decomposed. I was able to wrap all of them with tape to protect them for now. The jumper wire that connected the coils together had 3 strands left. I found some similar wire, and made a replacement the same length. Now I have no spark if I connect that wire. Disconnect the wire and I have good spark on one cylinder.
Is there something about the length / impedance / material that I should know about? Or did Mercury just put magic in the wire?
I have the part number of the wire, but it's listed as Obsolete, so finding an exact replacement is gonna be difficult.

 

[oldman570]

Re: 1971 Mercury 9.8 ignition wiring impedance

Fine stranded wire of the same size should work and not cause any trouble. If you lost spark on both coils then that coil/cyclender ing. is the trouble, or the wires that come from under the flywheel and points are bad and need to be replaced. DO NOT move the points setting as they are maker points and are/can be a SOB to get set correctly. Pull the flywheel and see if the wires are bad under it first. You will have to pull the stator plate inorder to replace those wires. New wires for that motor can be bought at Old mercs website and are not that $$. You should get a service manual for that motor as you will need it to understand just how the maker points system works. It is a good investment for the $ spent if you plan on keeping the motor. Coils for the motor are very $$ and the coils usually don't go bad. That motor is about one of the best around as long as it is maintaned as it should be. JMO
Oldman570

 

[kazeej]

Re: 1971 Mercury 9.8 ignition wiring impedance

Fine stranded wire of the same size should work and not cause any trouble. If you lost spark on both coils then that coil/cyclender ing. is the trouble, or the wires that come from under the flywheel and points are bad and need to be replaced. DO NOT move the points setting as they are maker points and are/can be a SOB to get set correctly. Pull the flywheel and see if the wires are bad under it first. You will have to pull the stator plate inorder to replace those wires. New wires for that motor can be bought at Old mercs website and are not that $$. You should get a service manual for that motor as you will need it to understand just how the maker points system works. It is a good investment for the $ spent if you plan on keeping the motor. Coils for the motor are very $$ and the coils usually don't go bad. That motor is about one of the best around as long as it is maintaned as it should be. JMO
Oldman570

I checked under the flywheel, and everything looked ok under there. The points are nice and clean, and the wires leading out are ok until they are out from under the flywheel. Then the insulation just flaked and was falling off. I had a nice blue spark from both coils, but the jumper from coil to coil disintegrated when I tried to tape it up. So, I'll try to make up a wire just like the old one.

Thanks oldman570!