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Conversion from 24v to 12 volt starter on JD

C

chas036

Member

I acquired a 24volt electric start 720 Diesel but without the starter or generator. I am curious if anyone here has converted their 24 volt 720 or 730 to a 12 volt starter, and if so, can you recommend a place where to get a 12 volt starter with the correct drive gear teeth to match the flywheel on a 720.


I know all the diehards are going to say to stick with the 24 volt system to keep it original, but I really don't want to deal with 24 volts, and besides, the battery box is all rusted out and corroded and I already have a 12 volt box and seat that I can put on the tractor. Also I already have a 12 volt alternator that I can use too, so I just need to know the correct 12 volt starter to buy and where..
 
I don't see why not. Lots of guys convert their 4010/4020 to 12v,I would think a 720/730 would be the same. As for the starter,just have it 'rewound' for 12v at a starter rebuilder.
 
(quoted from post at 21:08:09 06/17/18) I don't see why not. Lots of guys convert their 4010/4020 to 12v,I would think a 720/730 would be the same. As for the starter,just have it 'rewound' for 12v at a starter rebuilder.
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The only 24 volt starter that was converted to 12 volts that I've seen didn't start a 4020 very well. Plus I've read starters converted from 24 to 12 volts don't start engines as well as an original 12 volt starter. 4020 owner installed a regular 12 volt starter that was designed for a diesel & it started great. I think 720 would utilize same 12 volt starter as a 4020
 
I not only converted my 24 volt 730 diesel to 12 volt, I also converted it to 16 volt then back to 24 volt. If you find a 12 volt starter that spins it fast enough let us know. There should be some threads on this in the archives for the John Deere forum. I suggest you do your homework before you spend a lot of money on this experiment like I did. Didn't work for me but your results may vary.
 
because it is more difficult to being two large cylinder pistons to the top of the compression stroke than six smaller cylinder pistons . Why the hate for 24V ? Will you be satisfied with a three season tractor ?
http://www.delcoremy.com/Starters/Find-by-Model-Family/50MT

http://www.delcoremy.com/Starters/Find-by-Model-Family/42MT

http://www.delcoremy.com/getmedia/a6f943ce-00ac-40b3-8725-7324cee819a1/Delco-39MT-Single-Page-Brochure-1-16.pdf.aspx
 
(quoted from post at 11:39:49 06/18/18) because it is more difficult to being two large cylinder pistons to the top of the compression stroke than six smaller cylinder pistons . Why the hate for 24V ? Will you be satisfied with a three season tractor ?

IIRC 2 cyl JD diesels have a decompression mechanism that can be engaged so engine can be turned over easier so flywheel can gain momentum than a 4 or 6 cyl diesel
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(quoted from post at 05:56:28 06/19/18)
(quoted from post at 11:39:49 06/18/18) because it is more difficult to being two large cylinder pistons to the top of the compression stroke than six smaller cylinder pistons . Why the hate for 24V ? Will you be satisfied with a three season tractor ?

IIRC 2 cyl JD diesels have a decompression mechanism that can be engaged so engine can be turned over easier so flywheel can gain momentum than a 4 or 6 cyl diesel
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What happens when the compression is returned and the fuel lever is pushed forward ?
You don’t wet crank a 2 cylinder do you ?
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b&d
Sorry I can't remember. It's been over 40 yrs since I started a JD 2 cylinder diesel engine. Are you stating you start a JD diesel without advancing the throttle from stop position while engine crankshaft is rotating??
 
(quoted from post at 13:42:22 06/19/18)
b&d
Sorry I can't remember. It's been over 40 yrs since I started a JD 2 cylinder diesel engine. Are you stating you start a JD diesel without advancing the throttle from stop position while engine crankshaft is rotating??
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That is what it states in the operator’s manual .
 
. A 12V system can be made to start the tractor fairly decent most of the time . If premium components are used throughout .
 
(quoted from post at 09:23:10 06/20/18)
(quoted from post at 15:53:39 06/19/18)
(quoted from post at 13:42:22 06/19/18)

That is what it states in the operator’s manual .
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Interesting! If engine starts without advancing throttle from stop position has does one control engine speed?
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Starting engine or electric . Roll the diesel without compression and without fuel . When oil pressure registers . Apply compression and immediately apply fuel by pushing the throttle lever up from the shutdown position .
Click to expand...
 
(reply to post at 08:16:37 06/20/18)
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I posted the info earlier but here is is again . The highest powered 12V Nip Denso is 5Kw or 7.5HP. The 12V Delco MT39 or 12V Delco MT42 will make up to 7.3Kw or 9.75HP. A well tuned four cylinder starting engine is good for 14HP.
IF and IF proper cables are used and IF two group 31 1000CCA or better batteries are used with a MT39 or MT42. Your 720 will be a good enough three season tractor . A coolant heater will make winter starts possible .
 
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