Big Block Into Short Frame

[71_Bronco 1,072]

Possibly looking into this conversion for my Commando 8. Ideally I'd like it to be somewhat of a direct swap, meaning the crank shaft will be in the same place, and the same size. This way I can re-use my existing engine pulley, belt guard, and deck set-up.

 

Found a guy local to me who has a couple of Cub Cadet 12 hp Kohlers (K301 I believe), with the short oil pans and matching 1" shafts (same as my K181).

 

I've seen the YT videos of @VinsRJ "Little Mule" with its 16hp Kohler, but that one is a newer motor I believe, and I'm not sure if his crank is in the same spot as the stock motor. It does look like he is using a stock belt guard, but I could be wrong.

 

Is this swap possible?

[stevebo-(Moderator) 8,363]

Check out vinsrj on you tube. He did it and has extensive steps by step on what it took. 

[ELECTRORIC 230]

I put a k301 on my 856 used a Cub engine with the flat pan but I did have to notch the frame for the flywheel housing and I put the battery in the tool box under the seat.

[WHX?? 49,486]

Yes check out his you tubes but be advised the problems you might encounter are child's play to him. Some cubs have a pan with an extended bottom for the rod dipper and that can cause problems. 

 

 

Edited June 3, 2020 by WHX24

[71_Bronco 1,072]

33 minutes ago, ELECTRORIC said:

I put a k301 on my 856 used a Cub engine with the flat pan but I did have to notch the frame for the flywheel housing and I put the battery in the tool box under the seat.

 

Pretty much exactly what I was thinking right there. Even the battery re-location as well.

 

Were you able to re-use the stock pulley and belt guard? Or was the crank location too far off?

[ELECTRORIC 230]

I changed trans to a 8-speed and had to change pulley sizes had to make a new belt guard but I would think if you keep pulleys the same your belt guard should work may need to change mounting flange were it mounts to engine

 

[Herder 2,354]

[littleredrider 409]

I’m putting a k341 in my 606. I used an aluminum pan from a deer I think, flywheel bearing plate is just bout touching frame, tho I haven’t checked pulley alignment but appears to be close. Also battery is behind motor, stock location for small motor short frame. Not sure if there is a difference but battery tray is from a lawn ranger. I can’t get pics of yah want

[ebinmaine 68,879]

4 hours ago, Herder said:

[71_Bronco 1,072]

Okay, quick question for anybody with a K301 12hp Kohler. Can someone get me a measurement from the bottom of the block (where the oil pan bolts on) to the center of the crank?

 

I just measured the height of my K181, and got 4-5/8" from the top of the frame, to the center of the shaft.

 

Once I have the dimension requested above, this will tell me how much room I have left for an oil pan, and still keep the crank pulley in the same location as the stock K181, or it will tell me if i will need to notch the frame as electroric did.

 

Thanks!

[ELECTRORIC 230]

I can measure mine tomorrow but the reason I notched the frame was because I used the bigger flywheel w/electric starter so the notch allowed me to move the engine to the right for hood clearance and get the pan centered on frame.

[71_Bronco 1,072]

13 hours ago, ELECTRORIC said:

I can measure mine tomorrow but the reason I notched the frame was because I used the bigger flywheel w/electric starter so the notch allowed me to move the engine to the right for hood clearance and get the pan centered on frame.

 

Thanks, I understand now. I read it as you did a notch for the whole motor, not just the flywheel. My mistake 

[VinsRJ 723]

Hello, the swap to a big block is not that difficult into a short frame, you will although have a couple of things to modify, its not a direct swap.

 

As mentioned you will need to run a thin oil pan on a big block (K-Series/Magnum 10-16hp)... I ended up machining my own oil pan in order for it to work the way I wanted.

 

The crankshaft of the big block will be located a touch higher that the stock motor (K-Series and Magnum are the same), I was able to use my stock 857 belt guard with some slight modifications.

 

I ended up using the engine pulley off a 310, again it worked with the 857 belt guard with slight modifications.

 

I relocated the battery under the seat pan, IMO that's were it should have been located originally, LOL

 

If you run a Magnum motor beware that the Magnum blower cover will not fit under the short frame hood, you will have to modify the blower cover to fit, and you cannot run a K-Series blower cover on a Magnum motor due to where the ignition coil is located.

 

These are just a couple of things off the top off my head... PM me if you would like to discuss further...

[71_Bronco 1,072]

Thanks for the reply VinsRJ.

 

One thing I was thinking, was that if the stock, thin Cub oil pan was a little too tall, would it be possible to deck it slightly to get the correct crank height? I don't have a motor or pan in front of me to measure it all.

 

I did see the videos on your lil mule and the custom pan, that was very cool.

[VinsRJ 723]

The mounting flange of a stock Kohler thin pan is not very thick, I thing it could be done... But keep in mind that when you machine the pan down you may run into an issue with the connecting rod dipper, there is a good amount of clearance between the rod dipper and a stock thin Kohler pan, would there be enough to do what you are thinking, that I do not know for sure with out measuring up all the parts you would be using.