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View Full Version : Importance of good grounding on coil



am_dew
08-28-2006, 12:29 PM
"I just got back from a week long vacation at my family's lake front cabin on Lake Almanor, CA. Of course, I took the boat. This was only the second time I've had the boat out after installing a Pertronix Ignitor electronic ignition conversion kit on my AQ130C engine. Despite it running flawlessly the first time out after the conversion, I ran into a little problem on vacation that baffled me for a few days. After taking the engine up to cruising speed (4000-4600 RPM), the RPMs would intermittently quickly drop 300-500 RPM and then recover. This RPM fluctuation happend primarily at the upper end RPMs. I tried adjusting the air/fuel mixture on the carbs to no avail, I checked and adjusted the timing, verified the butterflies on the carbs were operating properly, etc. Finally, while my girlfriend was drving and I was back looking at the the engine while we were cruising and the RPM fluctuation was happening, I noticed some very small sparks around the ground post of the coil. After shutting the engine down, I found that the terminal attached to the coil's ground post was loose and you could wiggle it back and forth on the ground post. This coil does not have threaded posts so I just improvised and used plastic zip ties to pull one of the wires attached to the coil's ground terminal in such a way that the terminal was making constant and solid contact with the coil ground post. The boat ran perfectly after that. I need to find a better solution on securing the ground terminal to the coil post, or I may just buy a new coil...the Pertronix coil made to work with the Ignitor.

I also had my ongoing issues with lowering and raising the outdrive but I was able to overcome those, albeit with some frustration, so I need to try and resolve them instead of just dealing with it.

But, despite the small issues, the boat ran great and we had a very nice, but too short of, vacation."

am_dew
08-28-2006, 11:28 PM
"In case anyone is wondering, this is the top of the troublesome coil. The post/terminal on the left is the ground, which was causing problems. You can see the temporary "fix" I applied using a plastic zip tie to secure the terminals against the coil terminal posts. I ordered a Pertronix coil today to replace this one which has seen better days.

http://www.marineengine.com/discus/messages/12487/24989.jpgCoil

El Pescador
08-29-2006, 01:49 AM
"Bob, I have seen a few instances where the coils have been relocated from the engine to the transom, just to keep them a bit dryer. You may want to see whether or not this is an option in your case.

Thanks for posting the info. You are right, your coil has definitely seen better days."

am_dew
08-29-2006, 09:32 AM
"El, thanks for the suggestion however my engine compartment does not get much water in it at all, if any. The residue you are seeing in the pic above is remnants of oil that blew out of the crankcase breather tube one day from a bad newly rebuilt engine that is no longer in the boat. I just never bothered to clean it up really well. If I were to relocate the coil to the transom, wire length would be an issue, especially the wires coming from the distributor...can they be lengthened by a standard splice butt connector without fear of losing voltage, etc.?"

El Pescador
08-29-2006, 10:16 AM
"Bob, if you don't have moisture problems, you don't need to relocate the coil. However, if you do, lengthening the wiring should not lead to any voltage drop.

Most of the boats I have seen with the coil relocated to the transom have a 4-cyl Volvo OHC engine. In those engines the coil is originally located above the bellhousing and that area normally coincides at the end of the engine cover, which makes the coil prone to get exposed to water."

am_dew
08-29-2006, 11:28 AM
"The only time I have seen a tiny bit of water get into the engine area on this boat was from deceleration backwash when the engine cover was open or removed. When the engine cover is on, everything back there stays completely dry."