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Replace Magnum 18 with a 16 hp K341?

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#1 Tennblue59 OFFLINE  



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Posted December 24, 2014 - 04:48 PM

I've got a Cub 1861- (the one with the kohler magnum18 hp...). It's a project that I've been tinkering with in my spare time..... Tractor is somewhat beat up, but would make a good basic worker, nothing beyond that.


ANYWAY.... motor was pretty worn out - on the fence about rebuilding it given the cost of m18 parts. And don't want to invest in putting a newer v twin in it - its basically fix it up and sell it to one of the neighbors as a worker/grass cutter, part it out, or spend the money to go through the magnum and do it right - but not sure if the finished tractor would be worth the cost of the refurbish.... 


On to my question.... I've got several 16 hp k341's laying around. Thinking about dropping one of those in there. Anybody ever replaced a twin with a single like that? 


The 341 is 2 hp down on the twin. But it's only pushing a 48" mower deck - My ford LGT165 basically doing the same thing with the thumper single and it has plenty of power.... More vibration, but at speed (this is a hydro tractor) the single evens out pretty well. The K engine may not last as long (theoretically), but is dirt cheap to rebuild if ever needed compared to the M twin!


I know the ignition wiring is different, but not a major deal. Adapting/lengthening the drive shaft should not be a problem either and the engine mounts on a plate, so easy to drill new holes to mount it. Compared to the twin, there is plenty of room for the little single, and height, while different is not an issue. My 341 has same type of electric clutch on it already so that should be no issue. Actually looks like the engine switch would be fairly easy, as these things go.....


I don't need this  one, just trying to get it to utility status so I can find it a new home. And of course there would be full disclosure if it was sold - :thumbs: . So it CAN be done, but is it WORTH doing?

Edited by Tennblue59, December 24, 2014 - 04:57 PM.

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Posted December 24, 2014 - 04:54 PM

Why not its winter and you already have an engine ?

#3 Tennblue59 OFFLINE  



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Posted December 24, 2014 - 05:03 PM

That was my thought! Ok, it won't be "AS GOOD" as with the original engine, but if it does the job...... - Guess that's the question! Want to make sure its worth doing before I spend the time....


Working on getting the Kubota diesel in the "green" 316, and a couple other projects, so I don't want to spend a huge amount of time on this one...

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#4 Jlaws OFFLINE  

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Posted December 24, 2014 - 05:24 PM

I believe your going to run into driveshaft height problems . I'm not sure about the 1861 but I believe it uses the same engine plate that the earlier 782 used .


They put a single K 301 engine into a 82 series 1282 , but it had two bent flatstock type brackets that mounted between the engine plate and the engine to raise it about an inch or so to get the engine in line with the driveshaft .


I'm not 100% sure , since the 1861 Cyclops model is slightly different than the preceding 82 series models , but they are very similar if not the same in the frame engine plate setup .

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#5 superaben OFFLINE  


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Posted December 24, 2014 - 05:30 PM

I agree about the drive shaft issues, although that can be corrected. 


I'd also be interested in keeping that Magnum going.  I'm a Magnum fan, it is a K series with electronic ignition.  It really doesn't get much better than that.   I am aware that the twins are different than the K, but every twin I have messed with has been well worth the time and money to make it right.


However, it is hard to justify putting money into a Magnum and still ending up on top in a resell situation. 


Ben W.

#6 Tennblue59 OFFLINE  



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Posted December 24, 2014 - 06:03 PM

Thanks Ben - I realize the magnum is worth the money, just don't think it would be worth it in the Cub (sacrilege, I know!!!) THAT I HAVE. If I got the Cub running on the cheap with a different motor and sold it, I would probably put the money toward fixing up the magnum (as time and $$$ permitted). In a nicer or more desirable Cub/Deere/???, the magnum might be worth the rebuild cost. I actually ordered some parts to put toward rebuilding it eventually.

It's that grey area - the tractor (engine aside...) is nice enough that I hate to scrap it, but I don't see it commanding the value that fixing the engine would demand. And I don't NEED it for personal use - already have enough running and waiting-for-attention projects that I would be more likely to hang on to. If I were fixing it FOR ME to keep and use, I would drop a kohler/Briggs/Honda 18hp V twin in there! Actually plan to do that with my Ford LGT if the engine goes or "when I have time"!

#7 diesel nut OFFLINE  

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Posted December 24, 2014 - 09:41 PM

Other than the drive shaft height issue there's the oil pan on the single.  If it has the shallow pan that the Cub Cadets used it shouldn't be that big a deal to make brackets to hold it.  If it has the big pan like the early Wheel Horses I'm not sure if it will fit without notching the frame to set it in.  I remember my dad repowering a Cub Cadet 1210 for a customer because he got a good deal on a magnum 12 that he was told would be a direct bolt in.  It wasn't because it had the big pan and he ended up cutting something to make it fit but i don't remember what exactly.  Hope this helps.          Stewart

#8 Tennblue59 OFFLINE  



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Posted February 04, 2015 - 11:03 AM

I figured I would post an update....

I have enough other things going on (the diesel conversion of the Deere 316 is slow going, among others...) so decided to shelf this for a while. Pushed the tractor into a dark corner for future attention.


But I found some time and bench space and tore the magnum down to see what kind of shape it was in. Overall, the engine was not too bad. I replaced a rod that showed some signs of seizure, polished the crank, honed the cylinders and put in new rings, and am waiting for new crank seals (flywheel side had been leaking). Replaced a valve and did a valve job on the other 3. Inspected the oil pump for wear/breakage, etc..

The crank bushings show wear but were within tolerance - basically that's the story of the engine - it definitely has some hours on it, but aside from some breakage, still has a lot of life in it!  Getting it back to good running condition won't be too bad cost wise...


Too bad parts are so expensive on these magnums - its a good design built for the long haul! Doing a total rebuild back to "as new specs" would be $$$. Just the bearings/bushings for the crank are $70 each, with oversize ones going for a cool $140 a pop! You could drop $500 - 800 in new parts easy, before machine-work costs! Doing a teardown is definitely more work than for a kohler single (because of the split case), but I'm used to splitting cases for chainsaw and motorcycle work anyway...


Soooooo, looks like I'll get the engine fixed and running and back in the cub. Then run it for a month or so and see if everything works ok before it goes to a new home.

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#9 KennyP OFFLINE  



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Posted February 04, 2015 - 03:57 PM

Glad you got it fixed. Hope all goes well with it! I have an M18, just haven't put it in a tractor as yet!

#10 OldAllis52 OFFLINE  

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Posted February 13, 2015 - 10:37 PM

Just for a reference the 1050 uses the same frame as the 1861 but has a K series or Mag 10 in it. To mount the K-341 you would need the mounts and isolaters from a 1050. I think those might be the same as a 1250, 1450, or 1650 but I am not sure.

I feel your pain on the price of the M18,I'm building two of them.

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