Rebuilding my KT17, piston size question

[ol'George]

you are too young to remember how things were on the farm.
sometimes the "good old days" had their draw backs,
but we survived just fine.
nice to do things by the book, but also nice to "do" when you didn't have the book, and funny thing, it worked just fine.
We didn't mind making what we didn't have or was not available.
It was a long and costly wait to get parts by postal mail or from a
Sears/Wards /Western auto catalog.
today we have Computer/Telephone/instant communication.
times have changed, some for the better some not.
but rewarding as hell making something from nothing.
anybody can change parts, a machinist/mechanic can make that which he dont have.
just a personal thing, not up for debate.

[J-Mech]

Originally Posted by ol'George

you are too young to remember how things were on the farm.
sometimes the "good old days" had their draw backs,
but we survived just fine.
nice to do things by the book, but also nice to "do" when you didn't have the book, and funny thing, it worked just fine.
We didn't mind making what we didn't have or was not available.
It was a long and costly wait to get parts by postal mail or from a
Sears/Wards /Western auto catalog.
today we have Computer/Telephone/instant communication.
times have changed, some for the better some not.
but rewarding as hell making something from nothing.
anybody can change parts, a machinist/mechanic can make that which he dont have.
just a personal thing, not up for debate.

I wasn't debating. And no, I'm not all that old. But I do work on all that "old" equipment. Sometimes for the "older" guys. My point on this is that I'm familiar with the insides of older engines. The tolerances could be measured with a tape measure (not really). They were "loose" engines. Take an old 2 cylinder Deere. The first over-bore size is .045". You can run a standard ring all the way to that point with virtually no ill effects. Now.... things are a little tighter. Better quality machining, better metals. You can't get away with things like that anymore. It's not bad, it's not good, it's just the way it is. You can't go honing and re-ringing like you used to because it just won't work. It's kind of frustrating trying to explain why you can't do things like that when someone from your generation comes along and says "Well, we used to do stuff like that all the time!". Yes, yes you did. And it WORKED. But, things now are different. Motors are different. I respect what you did, and for the reasons you did it. Please respect that I'm familiar with more modern process, and machines. I don't give impractical advice. Just concise, and consistent to the relevant machine. FWIW, I grew up farming. We were a "poor" farm. We did a lot of things that you shouldn't do. Most of the time it cost us more in the long run. I don't mind "making it work", but I learned a long time ago that sometimes a patch just cost more than a fix.

Example: We had an 856. Started missing. I told Granddad we needed to fix it before it ruined the engine. I suspected an injector. Pulled the injectors and had them tested. They were bad. Replaced them. Still missed. Pulled the valve cover and found a broken valve spring. I ordered one. Granddad said "We don't have time to fix that we need to plant!!". I told him I was going to change it with the head on, and that the spring would be in the next day. I could have it fixed in no more than 2 days. He and dad overruled me. I told them your tractor, your decision, but keep it on the planter, don't disk with it. Well..... granddad put it on the disk. Just to do the end rows "It won't hurt"..... Locked it up. Scored #6 cylinder. The one the valve spring was broken on. Now, were were out a tractor and the $$ for a rebuild. Cheaper fix was a valve spring. The correct way would have been to pull the head and do a complete valve job/rebuild. I was willing to just replace the spring. Cost way more in the end.

I'm all too familiar with that mentality, and "doing what it takes". But when I give others advice, it is the best I know and the least risky.

I'll also say, I agree that a mechanic or a machinist can make things work. I'm not going to go into the million things I've fixed. I agree with that statement. But, not everyone is a mechanic, or a machinist, or has access to a cheap one.

[NCDiesel]

I think actually you both agree: Sounds like you are both saying that smart decisions are timeless; and transcend class, age and temperament.

"Making do" works: When applied inside the framework of a smart decision.
"By the book" works: When applied inside the framework of a smart decision.

Bad decision making like buying what you cant afford, or rushing an asset into production before its ready; is the real culprit - not the approach or methodology.

But back to my question: If he has an 003" piston, why is both his piston and bore measuring stock? Seems like one could not fit in the other without one of them being worn and out of spec.

Just curious,

[ol'George]

Well one situation could be as I stated.
I set many a SBC and BBC .0015 to .003 max piston to wall clearance and they run good and quiet, and set a little more on forged pistons but forged were noisy on start up/cold.
these were not race motors.
The afterformentioned 2 cyl Deeres running coffee can sized pistons,
(Aluminum not cast iron) don't run much more than that.
but we are comparing an air cooled to water boilers.

Be it mine, I would be mikin' the piston shirt @ it's biggest just above the bottom and the bore with a telescoping gauge that I have acquired a feel for, never liked a bore gauge but that is personal preferance.
Then I would know where I'm @.
but as I said before, a .003 is just that, 3 over.
I don't know about today but years ago pistons were select fitted to the bores, and varied as much as a tho'or two in the auto industry.
On Gm, the bore code was stamped on the pan rail of the coresponding cyl.
don't know if kohler would go to 3 over though, from the factory.
Now I'm wondering if this a series 1 and if it is, there is not a lot of parts avail for it.
ya you can modify and adapt later but not for the average guy with no machining ability.
Hell I converted a vertical to horizontal just cause I could.

[dvogtvpe]

Originally Posted by NCDiesel

I think actually you both agree: Sounds like you are both saying that smart decisions are timeless; and transcend class, age and temperament.

"Making do" works: When applied inside the framework of a smart decision.
"By the book" works: When applied inside the framework of a smart decision.

Bad decision making like buying what you cant afford, or rushing an asset into production before its ready; is the real culprit - not the approach or methodology.

But back to my question: If he has an 003" piston, why is both his piston and bore measuring stock? Seems like one could not fit in the other without one of them being worn and out of spec.

Just curious,

My guess is the measurements are off. I find it unbelievable rare that there's as little wear as He says. in an engine that old. thats just my opinion.

[dbuck]

I rebuilt a K 301 last year and when I tore it down. It had a .003 piston in it. I ask a old time mechanic at the CC dealer that I buy some parts from and he told me that when they first bored the block and it is not to spec, they then bore it over .003 bore to correct the mis-bore.

[dvogtvpe]

whats the out of round readings and taper of the bore?