Bendix Coils Test Good, But Won’t Fire In Motor
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Anonymous
Replies: 251
Topics: 33August 10, 2017 at 11:21 pm #62828Interesting thought Jerry. If no boot, maybe application of some liquid tape would help.
KirkAugust 10, 2017 at 11:35 pm #62829I agree J.W. Start with basics cleaning everything including the points bolt to remove any oil, Replace the wires, polish the contacts, junk the caps & check for out of round stater & run a bonding wire, mag to block. I use Super Corona Dope & fine glass cloth to help them also. No problems with my KG7, KF7 or my KH7 all bendix.
August 11, 2017 at 3:14 am #62842And, BTW, when I replaced the first original KG7 coil, I fou9nd that the high tension wire was just twisted at the coil lug, NOT soldered. I continued that practice. Figured Carl knew what he was doing when it came to mags.
August 12, 2017 at 10:55 am #62898I have pulled my hair out agonizing over seemingly all details of Bendix mag woes. When you get one that kicks your butt, after all basics have been checked, run the spark plug gap at .015" and you will most likely be amazed at the results.
Long live American manufacturing!
August 12, 2017 at 1:05 pm #62906Yeah, Bill, back in the old days we had to run wide plug gaps to allow for the lead and ash buildup.
Plug cleaning was frequent. 🙁December 16, 2018 at 1:44 pm #160264#160253 Edit Reply
Hello,
Brand new to this hobby as I picked up a 1948 Mercury KE4 for free. It is in great shape but it has been sitting in a barn for 20 years. While trying to resist the urge to take it completely apart I have decided to do a few things first to determine if it is worth it. Easiest thing is a carb re-build and clean. But the ignition stumps me.
I have determined through the service manual that I have the Scintilla ignition and I removed the coils to bench test them on an auto ranging Fluke meter.
Primary reads 3.2 Ohms on both coils and secondary reads 5.7 on one and 7.2 on the other. Both have cracked casings.
Are these BAD? If they are I have read that there is an obtainable replacement that fits the frame and has the same performance characteristics as the Scintilla with some modifications. Does anyone have instructions on this?December 16, 2018 at 7:06 pm #160302One mechanic told me sometimes it is the rotating magnet that is the issue with weak spark.
Make sure you independently test the points in the open and closed position. There are small insulating fiber washers that insulate the terminal from the body of the points.
December 17, 2018 at 12:25 pm #160439- This reply was modified 3 years, 1 month ago by The Boat House.
December 18, 2018 at 11:57 am #160630As Dave Bernard says, don’t overlook condensers. And, don’t do a simple “ohmmeter check” on your condensers either! Just like spark coils need to be tested at operating voltage, so do condensers! Your ohmmeter test (and most capacitor testers) will only measure the capacitance using one or two volts. I’ve seen MANY condensers that “measured fine” on capacitor meters, that promptly shorted out when put back in a motor, and were exposed to the full operating voltages that magnetos generate (often 300 to 400 V peaks!) I’d be embarrassed to admit how many times I’ve made this mistake myself…..
–wmohat
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Bill Mohat MS/CIS, BSEET, CCNA"You can avoid reality, but you cannot avoid the consequences of avoiding reality." --Ayn Rand **********************************************
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