Kohler K Series block interchange

[PTWannaHave]

Hello all,

As you may have read/noticed in another thread, I will be needing another K321/14hp block... They're rare in my neck of the woods, and it rains 12hp blocks... They look so similar to my untrained eye, that I was wondering if a 12hp block can simply be bored out and fitted with 14hp internals and flywheel? (Is the head even different?)

More generally, and for more members' benefit, is there and acceptable list or rules of which smaller blocks can be converted into larger displacement blocks?

Thank-you in advance,

[Klapatta]

The head will interchange between the 12 and 14. It's the 16 that has the additional bolt pattern.
The only direct block interchange that I am aware of is any K241 block that is cast marked K301, these can be bored safely to 12HP dimension. Not all K241 blocks have this marking.
With plenty of those 12's around the point seems kind of moot.

[Merk]

I wouldn't bore a 12 horse (K301) block to a 14 horse power bore. The is not enough metal cylinder area for it to last very long.
You have 3 choices: find a another 14 horse power block, run a stock 12 horse power engine or build a modified/hot rod 12 horse power block. You will need a #26 carb for a stock or modified 12 horse engine.

Some 10 horse power heads will fit on an 12 and 14 horse blocks. Biggest problem you may have with 10 horse heads is valve clearance.

If you decide to go with another 14 horse block you need to watch exhaust valve size. K321 had 2 different size exhaust valves. If your spec number ends with a d it has the large exhaust valve.

[PTWannaHave]

Thanks for the feedback!

Lots of useful info at http://gardentractorpullingtips.com/engine.htm . (Towards the middle of the very long web page.)

I was hoping to use my K321 crank in a K301/12hp block, but I don't think there is enough room in the K301 block for the K321 crank to spin freely.

Ciao,