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Post by olyman on Feb 14, 2021 0:03:16 GMT
The 292 left me stranded again  . Both times it failed shortly after running the engine for a long stretch, slowed down to turn around and as soon as I get back on the gas .... BLAAAAA... backfire and dead. Both times it would show a spark sometimes but would never fire much more than a few times. Last weekend after dragging it home and opening it up I found it had an aftermarket coil (kimpex i think) and a different condensor. The coil was definitely wanked as you could see a split up the back side, and the screw that goes inside the spark wire was crooked and not in the center anymore. So it would seem that it heated up, melted a little inside and failed. I happened to have a nice bosch coil to replace it with, so put it on and decided to re-use the aftermarket condensor. Put it all together and it ran like a top for at least a good 1/2 hour. So this afternoon same thing, slowed down after a long stretch, turned out the field onto the road and after 100' ... BLAAAAA. I havent opened it up yet but I know the coil has failed again. Why is this happening? Is it b/c of the crappy condensor? This engine has ran flawlessly for many years for me with no changes to it whatsoever. Something that did happen to me before it crapped out was the yellow ground wire that connects to the back of the engine case broke off... But that doesnt make sense that it would eat a 2nd coil. What do you think? |
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Post by Doo640ER on Feb 14, 2021 0:43:55 GMT
Hi Olyman, Sorry to hear of your ongoing struggle. I don't know why the coil would fail again, but if I were you I would try to source a OEM Bosch condenser (and coil), but that's just my OCD. I would also double check off of the grounds just to be sure that's not the cause of any issues. Sorry, unfortunately that's all I got. Life would be easy if you could just go to the dealer and get OEM parts for these old beasts. I'm hearing a lot of talk lately about how some of these aftermarket parts are junk.
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Post by powerwagon75 on Feb 14, 2021 16:40:14 GMT
Hi Olyman,
I would check your spark plug wire with an ohm meter. It may have burnout where the screw stab inserts. Bad wire/high resistance will cause excess coil heating.
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Post by olyman on Feb 14, 2021 23:16:02 GMT
That's a great idea. I think I will replace the wire while I'm at it
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Post by silverbullet on Feb 16, 2021 1:53:13 GMT
Sorry to hear of your misfortunes. Just a couple of questions for my own education:
Is the coil on that motor an internal one mounted on the stator plate, eg. like my pre 1971 299s have?
If so, is there any way to convert to an external coil?
I ask only because when I recently had my 299 apart I mused what a PITA it would be to change the coil. By comparison, for my twin cylinder 294, 340, 377 etc with external coils it's pretty convenient to diagnose issues by swapping a known good coil for one that is suspect. Perhaps there is no way to modify to external but thought I'd ask.
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Post by krusty on Feb 17, 2021 17:02:25 GMT
I want to laugh because I can share the painful experience and tears will be next  The condensor is there to limit the impact of arcing across the points when they open. You can run one without a condensor for test purposes if you want. When a condensor fails, it will ground out the voltage produced by the magneto coil resulting in no spark. There are some simple tests you can do....ideally using a 6v battery but 12v will work in a pinch. You can apply voltage to the + terminal of the coil, that being the non yellow wire to ground. When you remove the 12v to the coil, you should see a spark at the plug. A really hot spark. That will verify that the ignition coil is working and the wire is good. They can break down over time for no real reason, they can also stop producing enough voltage after running for 15 mins and they are warm. I dont know the bolt spacing from the internal coil as spoken about by silverbullet but if someone has a measurement I can confirm if a magneto coil would bolt right in. I assume it would. Also aftermarket internal coils are available as are aftermarket internal magneto coils. You can also check the voltage of the magneto coil and my experience is that it should be around 7 volts open circuit as you crank the engine. When I finally get new points I think I may produce a utoob video on old school ignitions. Everything I learned on that was from working on my old TJ that was not running right. Your second coil you swapped in just may be a fluke dud. Was it brand new? |
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Post by olyman on Feb 19, 2021 2:55:05 GMT
Thanks guys for the good ideas and support. Great info on the battery and voltage to look for. I still haven't had time to dig into this engine yet, but hopefully will soon.
The second coil I put on was just an old Bosch coil, and it is internal. Not sure about changing it over to external but I bet it's possible. Might have to if I don't have another good coil in the spare parts bin.
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Post by olyman on Mar 11, 2021 2:56:11 GMT
I put a whole different stator on from another known to be good engine, and ran a new spark plug wire. Since I didn't have any new spark plug wire on hand that wasn't old / hard / burned I used went with some 10awg welding style cable. I added some heat shrink around the whole length and then put the red silicone sleeve that was on it before, just for extra protection. That's a lot of copper compared to what most spark plug wires have, and the finestrands make for easy bending. Its also what I am using on the 640 and has been working well. I am going to test the old hardware later and use what's still good on old engines that can go on the shelf. Maybe identify what made it crap out.   |
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Post by Rockalicious on Jan 18, 2022 21:01:44 GMT
5000 ohms resistance on the spark plug wire. That about correct?
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Post by dando127 on Jan 18, 2022 21:58:18 GMT
I don't think there should be any resistance on a spark plug wire, at least for the old sleds...
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Post by Doo640ER on Jan 18, 2022 23:02:04 GMT
Sounds like the wire has a 5K Ohm resistor cap on it. If it does, I would remove it. Points ignition should not have a resistor spark plug cap. Nor should ya run a resistor plug. You want every bit of energy possible for a good, strong spark.
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Post by Rockalicious on Jan 19, 2022 12:44:52 GMT
HHhhmm. I tested my wire and got that reading. I have been running it on my elan for years then all of a sudden sporadic spark a couple days ago. Thinking it might be the external coil but figured I would test the wire anyway.
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Post by dando127 on Jan 19, 2022 13:07:09 GMT
They do make spark plug wire with resistance built in. It is to ptotect any electronics on the vehicle. It will reduce spark depending on how much resistance the wire provides.
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Post by bones on Feb 18, 2022 15:08:42 GMT
Changing from internal to external ignition coil as per question above.....Yes you sure can doo that. You can install a complete stator from a engine with external coil if you wish as it all lines up. Or you can remove the internal high tension coil from the stator plate and install a ignition generating coil. The mount spacing is the same. I think all crank cases for 69 and newer have the spot to mount the external coil but if the engine was originally a internal coil the mount holes are not drilled and taped.
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. Both times it failed shortly after running the engine for a long stretch, slowed down to turn around and as soon as I get back on the gas .... BLAAAAA... backfire and dead. Both times it would show a spark sometimes but would never fire much more than a few times.
