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Rework the rod?


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#16 Dayton_King OFFLINE  

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Posted February 28, 2018 - 09:51 PM

http://www.vogelmanu...-bearing-1.html


.020 bearings
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#17 MiCarl ONLINE  

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Posted February 28, 2018 - 09:52 PM

This discussion about parts before machining is interesting.  The guy that does motorcycle cylinders for me won't finish them until he has the new piston in hand.  I give him the cylinder, he figures out where he'll end up and tells me what piston to get.

 

It's got nothing to do with his machining skill - it's that you cannot count on the pistons being exactly to size.  By having the measurements of the piston that will go in that hole he can make it just right.


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#18 WNYTractorTinkerer OFFLINE  

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Posted February 28, 2018 - 10:03 PM

The K321 & K301 Cranks are the same if the blocks are from the same make motors.  Look up the Model & Spec numbers in the Kohler bible and you can swap the C/shaft from the 12 hp to the 14 (I recommend evaluating the bore and ALWAYS put in new rings.)  Here's a cheapie on EB:  https://www.ebay.com...tMAAOSw1NdaidfX  You will need rings also..

 

Looking up the Crankshaft kits @ Kohler the P/N's are the same BTW 


Edited by WNYTractorTinkerer, February 28, 2018 - 10:04 PM.

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#19 Mark 149 J. ONLINE  

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Posted February 28, 2018 - 10:05 PM

Lots of good information discussed!  I have a rod that I want to use in my K341 for my cub 169.  I think I will have a new bearing insert machine for it.

 

Thanks for this link Dayton_King


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#20 DougT ONLINE  

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Posted February 28, 2018 - 10:13 PM

The inserts in the rod doesn't bother me.

 

  My question is how good is the crank at .020 under? How deep is the hardening in the crank? I had a K181 turned 10 under and it wore out real soon and bad. I was told the grinding had gone past the hardening. It fit good when I put it together. Just didn't last.


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#21 WNYTractorTinkerer OFFLINE  

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Posted March 01, 2018 - 02:16 AM

The undersized rods are stock so .02" under size won't exceed the hardening depth per the manufacturer..  I think they are case hardened but don't quote me there..



#22 DougT ONLINE  

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Posted March 01, 2018 - 05:11 AM

The way I read the post, Kohler doesn't supply a 20 under rod, just the aftermarket.


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#23 olcowhand ONLINE  

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Posted March 01, 2018 - 06:46 AM

on that subject I was always afraid to buy parts before the machinist has started his work. Don't want to buy a 10-over and then find out the engine needs 20. Then I gotta buy another and am stuck with one. On the other hand if it will clean up at 10, I don't want to buy 20-over parts.    I want as much meat as possible left in the cylinder wall both for strength and for future rebuild ability  especially as they aren't a dime a dozen any more, many good blocks have been scrapped over the years,and the pullers have driven the price of "good rebuildable"  engines, too high. 

I can understand not being sure of what undersize or oversize parts one would need, but after doing so many, you get a good idea what to get.  Plus having a micrometer to check the crank journal, and bore gauges takes the guessing out of the equation for me today.  But when I did most of my gas engine rebuilding, I didn't have these tools, and never got it wrong....partly good fortune, partly educated guesses.


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#24 dodge trucker ONLINE  

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Posted March 01, 2018 - 07:07 AM

Lots of good information discussed!  I have a rod that I want to use in my K341 for my cub 169.  I think I will have a new bearing insert machine for it.

 

Thanks for this link Dayton_King

the machinist said on the phone yesterday that he uses the rod bearing shells from a 62 cu.in. Continental engine.... I figure they must be aftermarket, since I have not heard of any new engines from Continental in forever..... I don't think they are still around, are they? 



#25 dodge trucker ONLINE  

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Posted March 01, 2018 - 07:11 AM

The way I read the post, Kohler doesn't supply a 20 under rod, just the aftermarket.

 

yup that's right. but this machinist said that he can get inserts all the way to 40-under.   

as far as the depth of the layer of hardened material, Ive never had problem with an engine that I have taken the crank to 10-under. this would be the 1st small engine I will have had taken to 20-under, have done a couple of car cranks that deep, I know that with those they don't like going more than 30-under because of the surface hardening, and I'd guess that it would go deeper on a car engine's crank,  than it would on a 1 cylinder "lawnmower engine"..... 



#26 Achto OFFLINE  

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Posted March 01, 2018 - 09:36 AM

I guess you really only have a few options.

 

After market rod, which I've really never had any issues with a cast after market one. If you wish to go for a better quality after market rod then I would look into a billet rod, this would surpass the OEM cast rod for durability.

 

Machine your stock rod to accept automotive style bearings. Only question there in my mind - Is aluminum or Babbitt a better bearing material? Most engines manufacturers, other than the small engine industry use a Babbitt material. Even with a pressurized system the rod bearings rely on a splash bath to get oil.

 

Replace your crank and go back to the stock size or .01 under rod.

 

As for as the durability on a stock engine used under normal circumstances, I think your kinda splitting hairs between the options. If it were me I'd weigh out the options & probably let my pocket book make some of the decision for me. (I'm not saying "cheapest route wins", I realize that you don't want to have to visit this again in the near future.)


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#27 Achto OFFLINE  

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Posted March 01, 2018 - 12:43 PM

On the topic of parts before machining.

 

The Kohler manual gives specific measurements on piston to cylinder clearance per engine size. Most of these measurements have a tolerance of less than .002". In a machinist world that is a lot. Dealing with cast pistons this leaves some room to work with.

 

Now if we were dealing with hypereutectic pistons, this tolerance as well as the piston to cylinder clearance would close up dramatically. For example the piston to cylinder clearance may only be .002" or less. I would never machine a hole for a hypereutectic piston without having the new piston in my hand.

 

 Knowing that piston tolerances can vary, I find it best practice to have the parts before machining. Some machinist may disagree.


Edited by Achto, March 01, 2018 - 12:44 PM.


#28 dodge trucker ONLINE  

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Posted March 10, 2018 - 11:51 AM

ok this time the machinist guy did ask for a piston to be able to finish it out.... had one here that I'd gotten from Feebay that was supposed to be "piston and ring SET" but the only "rings" that came with were the spring clip/wrist pin retainers so I sent it back "not as advertised".... back to square 1 in that department....  the last engine he did for me he didn't ask for a piston. nor have any of the other machine shops I have ever worked with.....  this is definitely a dying trade, every machine shop I have ever dealt with closed due to the owner having retired, no young guys taking up the trade. 

​ANYWAYS,  on the rod rework idea,  one option I have known of for a lokg time is Brian Miller, (the pulling guy) who offers to bore the rod for an insert for $25 plus postage.... and $20 for the insert.   

 

This machine shop guy I am dealing with, said he can do it as well/ just need to come up with an insert, which was a bit of a chore. 

He told me of an application, which is an engine that has been out of prod. since at least the late 50s.... everywhere I tried to search came up "part number not found".... application is 62 cu. in. Continental engine, model N62. They used these in forklifts and the Massey harris Pony tractors too. 

 

  I found a few on Feebay, std and 0.010 were plentiful. 0.030 was kind of plentiful, 0.020 there weren't as many out there.... 

IDK the difference between new and old style bearings, pics looked the same but there was an up to/after serial number for that N62, for rod bearings. I got the "after"  or "new style".  

Part number Clevite CB542P or 2160P  

I looked up on NAPA, and a couple of other auto parts sites, searching for that number and came up "not found"....

 

I wound up buying a set of 4, only need 1 for this engine,  but I have a couple more K series Kohlers here that I need to go thru.... I have never needed to grind a Kohler crank to 0.020 under, before this one.  all of them I have done before, either were able to be polished standard, or ground "only" 0.010.  I sent in 2 rods  to be prepped for inserts, so I will have a spare. and since I saw several listings for "std" or 0.010 under inserts available, I should have a "one rod fits all" for my next K series rebuild.  

 

On the subject of Kohler rods.... everything I read says that the K361 ( 18hp) came with an ALCOA forged rod where anything smaller was "plain aluminum"....  what was the difference in the 16hp rods? Some places, I see they were "the same" as a 12 or 14hp, where other places I read say that the 16s also had the forged rod.  

I do know that some of the EBay sellers of aftermarket Kohler kits do specify a "REAL 16hp rod" vs a "regular 12 or 14hp one.... is there anything to this? (I do have a pair of 16hp K341s I want to rebuild eventually) 

 

 



#29 LilysDad OFFLINE  

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Posted March 10, 2018 - 05:43 PM

I seem to remember something about the K341 having an offset bore. Am I right?



#30 dodge trucker ONLINE  

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Posted March 10, 2018 - 05:53 PM

I seem to remember something about the K341 having an offset bore. Am I right?

I don't know. From what I had heard, they are interchangeable/ just forged alum. instead of cast. 






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