K161 vs K181

[Heatingman 971]

Are these the same block size?

 

I just bought a k161 for cheap to get a pulley I need for another.

 

Guy I bought it from said he pulled it off a parts tractor that was sitting outdoors for years, and the motor was siezed. 
 

He was able to free it up with a long term oil soak, then decided he did not need it.

 

I dont really need it either, but Im gonna scavenge what I can. 
 

But I got to looking at it, and their is a very small nick in the cylinder wall, mid way up. Thinking maybe thats were the seize happened. 
 

If left as is and attempted to run, maybe it would. But Im sure in time, that nick would cause a problem. 
 

If the nick is deeper then 30 thou, wondering if the motor could be bored out for a k-181 piston.

 

 

Then fixed up to have a good spare block for the future. 

[Heatingman 971]

[Pullstart 62,916]

I just read on here the other day ( @ri702bill? ) that the k181 deck height is taller?  

[stevasaurus 22,764]

I believe the block is the same.  The bore is different, the stroke is different, the cam shaft is different, but it is the same block.  You being from the Chicago area...there is a very good small engine guy in St. Charles.  If you want a good opinion, take it to him and let him look at it.  I had him do 2 of my K181S blocks 2 years ago.  PM me and I will give you his name and address and phone #.  He was excellent to work with.    he was a Kohler Dealer in the past.

[Heatingman 971]

@stevasaurus Does this guy do primarily automotive engine machining now?

 

Cause I just dropped off a block for a K181 to a shop in St Charles yesterday for overbore. 

Edited October 19, 2022 by Heatingman

[stevasaurus 22,764]

Yes!!  Sounds like you found the right guy.  

Auto Machine Inc.

310 North 6th Street

St. Charles, Il. 60174

1-630-584-1188  

(Kim)

Sound familiar???

[stevasaurus 22,764]

If this is the guy you found..see about walking around his shop.  Really cool!!

[Heatingman 971]

4 minutes ago, stevasaurus said:

Yes!!  Sounds like you found the right guy.  

Auto Machine Inc.

310 North 6th Street

St. Charles, Il. 60174

1-630-584-1188  

(Kim)

Sound familiar???

Thats them. 

[stevasaurus 22,764]

They did 2 K181S blocks for me.  The guy knows what he is doing.  It might take a couple months to get it, but worth the wait.  If you got to walk around the shop...8 cyl camshafts laying around...have a cup of coffee with Kim.  

[Heatingman 971]

So a little research. K161 bore is around 2 7/8 and the k-181 bore is around 2 15/16

 

stroke on the k161 is 2.5”

 

stroke on the k181 is 2.75

 

so I reckon if I have it bored over use the k181 piston, I’ll create a k171 … LOL 

 

but if I swap the cam and the crank with a future k181 that may have a jacked up bore, then I’ll get a k-181

 

I’ll ask the small engine guy about it when I pick up the block Im having worked on. 

Edited October 19, 2022 by Heatingman

[Achto 27,609]

If you bore a K161 out to the size of a K181 you will most likely not be able to use the K161 crank and connecting rod. I don't have every thing in my hand to measure but I would assume that the piston deck height ( distance from the wrist pin to the top of the piston ) is different from one engine to the other to accommodate for the length of the stroke. Looking at the numbers, a K181 piston on a K161 crank and rod may not reach all the way to the top of the cylinder at TDC. This would result in low compression. All the above is just theory that would need to be proved out with the proper measuring tools.

Edited October 19, 2022 by Achto

[Heatingman 971]

If I get around to tearing it down, I can measure against the K181 parts I have. 

 

But either way Im fairly sure their is a configuration that could be made to cobble a K-171 together. 

[Heatingman 971]

And if not, would be a viable future K-181 block

[squonk 41,158]

That nick will tear up a ring probably. Blocks the same. Internals and bore change the size.