engine swap

[mrc 1,087]

men,

 

thinking of replacing a very tired kohler 'k' series 10 hp engine with a 12 hp kohler magnum engine.

 

will it fit under the hood of a 'C' series tractor?

 

battery to magneto ignition.  new key switch?   wiring changes?

 

thanks in advance

regards

mike

[953 nut 66,861]

It will fit just fine.

Here is a thread I posted a while back that shows how to alter the wiring.

 

[MainelyWheelhorse 2,718]

@mrc I’m sure the more seasoned engine swappers on here can correct me if I’m wrong but when I built my C-141, I asked what the differences was between the K and Magnum. I was told it’s just the ignition. The physical engine size is the very close/the same with minute differences so it should fit. I was also told the key switch to run a Magnum has to be for the magneto ignition in the Magnum’s. for example, one from or for a 312. The K is points so that’s what you would already have. Don’t mix the two as the magneto to K would fry the coil etc… I didn’t run safety switches to simplify the wiring and almost a year later no issues. Do that at your own risk. @953 nut and @pfrederi also @ebinmaine are better versed in the nuances of K to Magnum wiring. At least this will get you pointed in the right direction.

[953 nut 66,861]

6 minutes ago, MainelyWheelhorse said:

the magneto to K would fry the coil etc… I didn’t run safety

Fallowing the thread I added above will allow the safety switches to remain actives with no major wiring changes.

 

 

Looking at the battery 103990 switch next to the magneto switch 103991 I decided to see what would happen if a 103991 (Magneto) switch was placed in a Battery Ignition tractor. With the exception of a frustrated person wondering why nothin works the outcome would be rather harmless.

In the OFF position the R and A terminals would be connected Ground, no big deal.

In the RUN position the I, A and R terminals would be connected, nothing would happen but no harm would come of it.

In the START position the S an I terminals would be connected, once again nothing would happen but no harm would come of it.

 

On the other hand, if this situation were turned around and the 103990 (Battery Ignition) switch were placed in a Magneto tractor things get a bit more interesting and a whole lot more expensive.

In the OFF position none of the terminals are connected and all is well.

In the RUN position the B, R, A and M terminals are connected and magic smoke will be released from the Magneto.

In the START position the B, A, S and M terminals will be connected and the engine will turn over but there will be no spark because the magneto already is toast.

[midpack 1,147]

I did the relay from K to Magnum. I would do the relay 10!10 times

[ri702bill 12,298]

I like the relay method - simple, compact, and easily removed if another K Series engine were to be installed later on....

[pfrederi 20,756]

The big plastic shroiud on the magnum may cause you clearance issues.  Just remove it (you can sell them for $$ and get a metal can air cleaner cover...

[19richie66 17,895]

I just installed a push button kill switch below the choke knob on my 417. Think it was a dash mounted horn switch off of something. Just like this but without the horn logo.

 

Edited 3 hours ago by 19richie66

[adsm08 4,657]

59 minutes ago, 19richie66 said:

I just installed a push button kill switch below the choke knob on my 417. Think it was a dash mounted horn switch off of something. Just like this but without the horn logo.

 

 

Last time I had to re-wire a magneto system I used a toggle switch for the kill. That way there was very little change of releasing it too soon and allowing the engine to restart while it was still spinning down.

[19richie66 17,895]

49 minutes ago, adsm08 said:

 

Last time I had to re-wire a magneto system I used a toggle switch for the kill. That way there was very little change of releasing it too soon and allowing the engine to restart while it was still spinning down.

Yeah but this way I won’t forget to turn it back on 

[Bill D 2,942]

I preferred powered ignition wiring harnesses.   The last tractor I rewired was a GT1800.   I purposely wired it for a powered ignition.   This provides the greatest flexibility for engine swaps.