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Onan Generators

Onan 12.5jc/3cr-1AA


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  #1  
Old 09-09-2017, 11:37:44 AM
DrewE92 DrewE92 is offline
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Default Onan 12.5jc/3cr-1AA

Dose anyone know where i can get a replacement distributor? Is there one i can cross reference at a parts store?
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  #2  
Old 09-09-2017, 02:10:11 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

I honestly don't know if there is one available, I doubt it!
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Old 09-09-2017, 02:29:14 PM
wxyoung2008 wxyoung2008 is offline
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Default Re: Onan 12.5jc/3cr-1AA

Hang on a while. Some of the guys will probably have some good pre-owned ones that they will let go reasonably.
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  #4  
Old 09-09-2017, 05:45:07 PM
DrewE92 DrewE92 is offline
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Default Re: Onan 12.5jc/3cr-1AA

Ok thanks guys. I pulled this one out got it all cleaned up I believe I got the advance and all back working will find out tonight
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Old 09-09-2017, 06:39:39 PM
Handyhiker1 Handyhiker1 is offline
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Default Re: Onan 12.5jc/3cr-1AA

Good news, good luck!
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Old 09-09-2017, 10:14:01 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

What was wrong with yours?
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Old 09-11-2017, 12:33:22 PM
DrewE92 DrewE92 is offline
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Default Re: Onan 12.5jc/3cr-1AA

I have had nothing but ignition problems with this thing (found it in a field at a friend's house) surprisingly no rat nest just a couple hundred wasp lol but some destroyed the control box had to be completely rewired, new relays and switches, new coil condenser and plugs, carb gone through finally got it to bust off and it ran alright back firing a little set breaker points and timing started right up ran perfect at put a small load on it and started skipping and miss firing that's when I noticed the breaker cam has some heavy ware and the advance was getting stuck not letting it spring back. Springs probably needs to be replaced and could use a new cap and button but its back together and run pretty good but I haven't put a load on it yet
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Old 09-11-2017, 01:55:43 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

I have this on a JC.

https://www.summitracing.com/parts/p...SABEgIjrfD_BwE

It's pretty much a bolt in change over. You could pull the points plate out of the one you have, then the springs then pull the retaining clip off and attempt to pull the cam assy. off the shaft, clean and lube it reassemble with the Pertronix.
I actually have a recent thread going about a JC dist. I can not get the cam to come off the shaft because of rust, still soaking it!
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Old 09-11-2017, 02:06:21 PM
len k len k is offline
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Default Re: Onan 12.5jc/3cr-1AA

Other alternative ideas , like magnet pressed into hole drilled in flywheel, car pickup coil and ignition modual. Might need 2 magnets, moduals, and coils for 4 cylinder engine
https://www.smokstak.com/forum/showthread.php?t=167037
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Old 09-13-2017, 12:08:28 PM
labans labans is offline
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Default Re: Onan 12.5jc/3cr-1AA

I don't know what you have tried for the soaking, but I cannot recommend highly enough using a mixture of ATF and Nail Polish at 50/50 ratio and you must shake it for at least a minute after mixing.
I am an automotive machinist and after using everything commercially available for 50 years I found this suggestion and I can tell you that there is NO second place mixture as this is in a class by itself.
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Old 09-13-2017, 12:24:32 PM
gchank gchank is offline
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Default Re: Onan 12.5jc/3cr-1AA

Is that nail polish remover and are you mixing it with a sexy red color nail polish?
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  #12  
Old 09-13-2017, 12:32:39 PM
labans labans is offline
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Default Re: Onan 12.5jc/3cr-1AA

Yes. I could have said Acetone but it is very difficult to buy 8 oz of acetone while you can get 8 oz of Nail Polish Remover for about $3, empty it into a spray bottle, then fill the nail polish bottle back up with ATF ($3 for a quart from Autozone) and pour it into the spray bottle and shake hard before each use.
Too much fun has been made of this mixture, but the fact that it works better than anything else is the proof in the pudding. Don't knock it until you have tried/tested it.
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  #13  
Old 09-13-2017, 12:54:16 PM
len k len k is offline
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Default Re: Onan 12.5jc/3cr-1AA

Walmart acetone in paint dept, ~ $12/ gallon. Also removes tree pine pitch well.

Careful, Some nail polish removers are cut with ~50% water and have other stuff in them (aloa, water based)

Last edited by len k; 09-13-2017 at 02:56:02 PM.
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Old 09-13-2017, 02:37:59 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

Quote:
Originally Posted by labans View Post
I don't know what you have tried for the soaking, but I cannot recommend highly enough using a mixture of ATF and Nail Polish at 50/50 ratio and you must shake it for at least a minute after mixing.
I am an automotive machinist and after using everything commercially available for 50 years I found this suggestion and I can tell you that there is NO second place mixture as this is in a class by itself.

The mix seems to separate after it sits a while. I have had 3 cylinders of a JC soaking for a year or two.
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Old 09-13-2017, 03:30:42 PM
Carteret Carteret is offline
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Default Re: Onan 12.5jc/3cr-1AA

There are many types of ATF nowadays, I would think that DEXRON would be the "original" ATF used in this formula? Ford used (uses) mineral based ATF back when.
Thanks
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Old 09-13-2017, 03:54:47 PM
labans labans is offline
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Default Re: Onan 12.5jc/3cr-1AA

Why are you soaking 3 cylinders for years?
The mix does separate which is why one must mix very well before using.

---------- Post added at 02:54:47 PM ---------- Previous post was at 02:51:33 PM ----------

I have had good luck with plain old Dexron from wherever it is cheapest, for this use. As far as 'additives' are concerned just read the label and get the one with the least additives. And if you wish you can spend the extra and buy a gallon. I just know what works after having tested this mixture over the last 12 months against all the other products I have used over 50 years and this mixture is great.
And if anyone doesn't want to use it, that is fine too!
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  #17  
Old 09-13-2017, 04:17:27 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 12.5jc/3cr-1AA

Pistons still rusted to cylinders!
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  #18  
Old 09-13-2017, 06:33:36 PM
len k len k is offline
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Default Re: Onan 12.5jc/3cr-1AA

If 3 years didn't do it I don't think oil will do it. With rusted bolts I find heat works MUCH better than any oil. Try getting cylinder hot, then cool piston, and hammer piston. People here like putting ATF and a rag as wick on top of piston and letting it burn.

I had pistons rusted once when I was ~ 15, we soaked it with penetrating oil every day for 2 weeks. Then cut edges of 2x 4 to fit in cylinder then sledge hammered the wood. Wood was ~ 8 inch long. Pitted cylinder required oversized pistons.

But looking back at it I'ld try to get section of steel cylinder the size of cylinder to put the force at piston skirts, so piston top doesn't cave in. Big socket for a bull dozer maybe, or nut for one and grind edges off?? Then hammer the steel. Using steel instead of wood you'll get higher peak impact force on piston, which is what you need break it free.
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