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140 Motor Rebuild Underway

897 Views 12 Replies 8 Participants Last post by  quintenblood_of_green
Hey all. I couldn't find my old thread so i just started a new one. I'm rebuilding the motor in my 69 140 that started developing a bad knock. Everything is back from the machine shop and looks excellent. My basic thought was if i'm going to spend the money to do it, i might as well do it right, so almost everything on the motor will be new or rebuilt. Here are some pics so far and there will be plenty more to come.

The block painted. One of the first things i did due to not wanting it to rust because i washed it real good to get that small grainy stuff out of the cylinder.

New master gasket set.

The motor had already been bored to .030 but the job didn't seem to good. The machine shop said it was out of round which caused the problems over time. He completely bored it out and we re-sleeved it back to standard bore. Then the valve seats were reground along with the valves. It looks awesome!

Crank was ground .010 and the rod has an insert because it is a standard rod.

New rod, piston, rings, and ground head. It's a little tighter so it'll have more compression which means more power!! (which is always a good thing

Then of course a new intake valve.

More pictures to come with the process!!

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Can I ask where you got your rebuild kit...i'm going to be doing a K301 soon and will be in need of some parts. Thanks, Joe
Good Logic Quinten on doing it right. How does the saying go.....

We never have time to do it right....

But we always have time to do it again....
Joseph, i got it from Kohler. Everything except for the main ball bearings on the crank are from them. I've heard mixed feelings about buying other company's parts but i felt that if the motor has lasted this long with those Kohler parts, it will do it again.

Paul, so true...

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Hey guys, been a while since i updated this. Have most of the block together. Need to put all externals on then done. (will upload pictures tomorrow) I had a couple questions though so any help is appreciated.

1. The exhaust valve is new in the motor. I needed to adjust the valves so got the specs from the book. When i adjusted to the right clearance, the valve would lift slightly on a non exhaust stroke. Is this the ACR working?

2. What type of oil should i use to break in this motor?

Again, any help is great.


Now that might open a can of worms an oil question.

i would use just plain ol' 30w oil. Never hurt a thing. I regularly use 20-50 mobile 1 syn right now.
Texas summers are pretty stinkin hot. No need to change weights down here as it never stays cold for very long
30 weight non-detergent then change after about 5 hours of use. The way I understand it, any particles left in the engine will not stay suspended in the non detergent oil as they would with detergent oil.


Great job you are doing on your K321!!! I really enjoy this post, and I hope the one I am about to start turns out as well as yours.

I am not an expert on the K321 by any means, but it sounds as though the exhaust valve opening slightly on the compression stroke would indeed be the ACR working. If you spin the crankshaft in the reverse direction, does this stop? If it does then it would suspect it is the ACR. If it still does this in reverse rotation, you may have something else going on.

I agree with David, oil might open a can of worms here, and I think I will feed it just a little.

Synthetic is great oil, but do not use this for the break-in!!! JMHO, I would wait at least 50 hours to ensure the rings are fully seated before switching to synthetic.

When I was younger, I was an A&P mechanic. On a fresh engine just after rebuild we would change the oil immediately after the first start-up run in which we set the timing and carburetor adjustments, and verified there was no leaks on all the seals and gaskets (typically, this was only a 15 minute process or less). Now granted this was aircraft engines, but I have also carried this practice over to any engine I rebuild. It is very cheep insurance to make sure the majority of the foreign contaminates after a rebuild are out of the engine as soon as possible (especially being as how the K321 does not have an oil filter). I would then follow the Deere service manual, and again change it after 2 hours. Deere then recommends changing in intervals of 25 hours (or 8 hours in dusty conditions). My personal process on a fresh engine, would be to change it again regardless in 8 hours (again just cheep insurance).

Non-detergent vs. detergent oils might also open a can of worms. Many recommend a non-detergent on engines without filters, and that it helps to seat rings faster. My personal thinking on this, if you change oil at the recommended frequency (or more frequently), you should not have contaminates suspended in the oil large enough to cause damage after the break-in period. And ring seating does indeed occur with detergent oils as well by normal application of light to moderate loads during break-in. JMHO I think today’s detergent oils are far superior to the non-detergent oils. I personally would use a high quality 30w detergent oil even during the break-in period. But as I noted, I would also change it far more frequently than recommended during the break-in.

Also drain the oil while it is hot, or as warm as you can handle to insure the majority of the contaminates are still in suspension during the change.
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Quinten ,yes thats the c/r working .it might come up from .030 to .043,if any more or less you can adjust it ,there is a small tap on the c/r that you can bend down or up to come into specs, David
Great to hear. Thats what i thought it was. More pictures later tonight!

Alright. Here is where i'm at right now. I didn't get a chance to take any between the other pictures and now because we kinda got on a roll and excited to get it back together and i totally forgot.

The motor pretty much back together. Valves adjusted, new points, new gaskets, new governor, and the flywheel painted.

Another shot of the flywheel...

New seals and painted block. I think it looks real sweet from this angle.

And the fresh milled head with new grade 8 hardware. I didn't put the stud back in cause i never liked it. I think it looks better and it will seal better this way.

More to come!

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since I don't know what grade bolts are original to the K engines, is grade 8 overkill for the head bolts? think I'd rather have a bolt fail than something else - just wondering????
Well i think the way i understand it is is that the head is what helps compress the air/fuel mixture so it needs to be tight to run. The grade eight hold up to heat and high strength better than most others. I think the head gasket would fail before anything else. Someone correct me if i'm wrong...

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