K301/K321 questions

wj-ihc · #1 08-11-2014, 11:11 PM

I have two 301 blocks that are in pretty good shape that I had hoped to rebuild but one is already 0.030 and the other is a loose 0.030. They both might clean up at 0.030 but I am afraid one or both may not. I also have two complete 321's that both need rebuilt. Does anyone know if a 301 can be bored to accept a 321 piston, creating a 321? The 301 and 321 cranks look to have very similar counterweights. I believe these engines are internally balanced, so can a 321 flywheel be put on a 301 crank, or vice versa? I would like to retain the correct size flywheel shroud for the tractor that had the 12. Would a 321 piston ran with a 301 crank/flywheel have any balance issues? Are the 301 blocks thick enough to be bored to 3.5" without overheating issues? Lots of questions, just hoping someone has been there/done that.

J-Mech · #2 08-11-2014, 11:22 PM

No, can't bore the 12hp out to a 14. The machine shop you use should have been able to tell you that.....

You can interchange the flywheels yes.

bocephus1991 · #3 08-12-2014, 12:51 AM

You could have the k301's sleeved , but don't know if it would be feasible. What kinda of shape are the 321's in? Are they 30 over already? If not just overhaul one of those ?

wj-ihc · #4 08-12-2014, 08:17 AM

Ok, thanks for the info. Haven't had either block to a machine shop yet, just measuring with my own tools at the moment. So the jugs on a 14 are indeed thicker than a 12? That's what I needed to know.

I haven't gotten the two 321's all measured up yet to know for sure if they can be rebored or not. Assuming they can, I will be alright putting a 301 backplate and flywheel on the 321 and running it in a 129 for a factory look? I wonder why they didn't order the 321's for the 147's with a smaller flywheel to avoid cutting the frame up?

dbuck · #5 08-12-2014, 08:41 AM

On the k301 blocks, you stated that one is already +.030 and the other is a loose +.030. So how are you going to clean them up @ .030? If you want to use either block have it sleeved and go back to standard.

wj-ihc · #6 08-12-2014, 08:52 AM

Quote:

Originally Posted by dbuck

On the k301 blocks, you stated that one is already +.030 and the other is a loose +.030. So how are you going to clean them up @ .030? If you want to use either block have it sleeved and go back to standard.

That was a typo. One block is 0.030, but still on the low side, so it might take a light hone and remain within the 0.030 specs. The second block is a loose 0.020. I hope it will clean up at 0.030. Sorry for the confusion.

bocephus1991 · #7 08-12-2014, 02:27 PM

What's the piston on the k321's say? Should have std for standard if they have never been touched. I would have a machine shop measure it if your not sure yourself .

austin8214 · #8 08-12-2014, 02:34 PM

My local small engine shop told me a few months ago that Stens is making .040 oversized pistions for these now. You may want to look into that. Good luck.

dvogtvpe · #9 08-12-2014, 06:19 PM

if you have a thick block you can go to a 3.5 bore on a 10 or 12 block but you do need to measure it to see how much meat is there. I had a thick 10 block one time that I went .090 over a 3.5 bore. ran it with no governor for years, now if you don't know what you're doing and bore a thin block it'll probably crack about the 3rd cooling fin down.

wj-ihc · #10 08-12-2014, 06:45 PM

Quote:

Originally Posted by bocephus1991

What's the piston on the k321's say? Should have std for standard if they have never been touched. I would have a machine shop measure it if your not sure yourself .

One 321 is 0.020, but I haven't got it measured up yet. The second 321 is not cleaned up enough yet to read the numbers.

I would consider 0.040 if the consensus is that it is safe. How much material do you look to retain on an overbore?