74 mercury 115 HP thunderbolt ignition 6 cyl

"At higher RPM'S charging

"At higher RPM'S charging system seems to overcharge battery and we have a spark or arcing that we hear as we run the engine. This arc seems to happen once we have been under way for a few minutes and is not in consistant intervals. We replaced the switchbox already. The serial number is 3941752, we thought about getting a rectifier for it but the rectifier that comes up for our engine is different than the one that the mercury repair manual shows...we have the one that the repair manual shows however, it isn't the same one that comes up for our engine so we are at a loss, PLEASE HELP IF YOU CAN. THANK YOU!"

"Eric, That motor has an unreg

"Eric, That motor has an unregulated charging system consisting of a stator under the flywheel and a full wave rectifier, mounted next to the switchbox. The charging system is about 6A and it is unlikely it is arcing. I guess it could overcharge the battery, if you ran for hours and hours at high RPM, but I consider it unlikely to do so. You can get a 25A full wave (bridge) rectifier from Radio Shack for $5 or less. It is a much better product than the OEM rectifier, but you need to ground the -DC connection and change the connectors on the stator and +12V wires to spade females.

If you do have arcing, I would suspect the distributor cap, ignition wires or coil. Clean the inside of the distributor cap to eliminate and carbon traces. Run the motor a night to see if the ignition wires are arcing. Pay attention to the lower ones, they go first. You can get replacements at www.oldmercs.com for $5.95 each"

"Hi Eric, I'm from Puerto

"Hi Eric, I'm from Puerto Rico and I have a Mercury 1150 1973 that I bought in Florida 4 years ago that something happened sometimes similar to the sparking you mentioned. In my case I replace the stator for a used one in good working order and mine use just 2 cables from stator. This 2 cables normally goes very rusted or broken around the stator connector area below the flywheel or exactly in a designated jumper area that the 2cables jump and has to go to the rectifier. Exactly where the jumper is, it should be a plastic base very small under both cables get together, why this?, every cable become with 6.4 or 6.5 vdc to connect to the rectifier and the rectifier send 12.9v to the battery and keep it charge. The plastic base could be broke in two parts and maybe its spark between the base or someplace where the cables is broken near any ground close to the engine. I also replace timing belt, rectifier and some rusty cables. Take care of the timing belt taking flywheel out! if need to see stator. Sorry for too much bla,bla,bla but you are the first one I read that have kind of the same engine as me. Take care Eric, best regards!. Write me back to my email if need to do some chat about this engine stuff. Pedro Moreno"