857 Refresh/Rebuild Begins

[rmaynard 14,922]

Back in October I picked up a nice 857. Didn't know if it ran or not because the carburetor was missing, but the overall condition of the tractor was good. So, I brought it home and put a rebuilt carburetor on it. It started and ran great with the exception that it was a heavy smoker.

 

 

 

I haven't decided whether to leave the metal as-is, or do a complete repaint, but I knew that something had to be done about the engine. So two weeks ago, after the single-digit weather warmed up and the snow melted, I removed the engine and began my engine rebuild.

 

First observation after removing the head revealed a lot of carbon, and some oil sitting on top of the piston.

 

 

 

The cylinder did not look bad, so I measured it with my new bore gauge.

 

 

 

The cylinder was still within the acceptable tolerances of a STD bore, There were no scratches or ridges, so the decision to just hone it made sense to me. So, I just received my new Ball Flex-Hone yesterday, and that will be the next step. My local, very reputable but expensive machine shop charged me $125.00 to hone the cylinder, lap the valves, and polish the crankpin last year on my K161, so I decided that $35.00 for a Flex-Hone was a good deal.

 

 

The crankshaft didn't look bad, so after removing it, I measured the crankpin. 1.185" and no out of round. Since 1.185 is the maximum wear limit, I decided to Plastigage the crankpin to connecting rod clearance. 

 

 

I got a measurement of .003. Since the maximum wear limit is .0025, I pulled out a brand new Kohler connecting rod that I had purchased earlier and Plastigaged the clearance with that. I got a measurement of .0175. So based on that, I am installing a new rod on the old crankshaft.

 

 

Since I am not sure of the source of oil burning, I measured the valve guides. Tolerances were also within specs. The intake and exhaust valves were not bad, just dirty, but the intake valve had about .001" wear on the stem. So I have decided to install a new set of Kohler valves. I lapped them in, and they are now ready to install.

 

 

 

The piston also looks real good.

 

 

It measured within acceptable specs, and also is not scratched or scored. A new set of Kohler rings should solve the oil burning problem.

 

 

Okay, that it for now. As progress is made, I will update.

 

 

 

[meadowfield 2,545]

excellent thread!  

 

techie with just the right amount of detail and pictures - will be useful for those looking at rebuilds...

[Tom. 70]

Hi,

Brilliant thread so far! I will be following very closely as I have an 856 with a smokey engine I'm about to restore so I'm sure this will provide me with plenty of help!

I'm looking forward to the next update.

Tom

[JERSEYHAWG / Glenn 4,487]

Nice start. Will be exciting to follow along.

Glenn

[specialwheelhorse 174]

Your ball hone will work like a charm an airplane mechanic I know had a complete

set of them and loaned whatever size I needed, and told me if everything is within

tolerance they will use them on aircraft engines. I now have a couple sizes of my

own now and after using them on a couple dozen engines with perfect results

I wouldn't trade them for all the tea in China. Oh yes this gentleman works for Ratheon

and works on aircraft all over the world. He just got back from Dubai  from working on

some Shieks  plane so I'm assuming he knows what he's doing.

Just give that dude a really good cross hatch, and you will be good to go!!!!!

[pacer 3,160]

Ball-hone/Flex hone ---bah, we all know thats a "Dingleberry" hone!! :)

 

Its sure works good too....

[Desko 552]

The "dingle berry" hone doesn't take as much material away as a normal hone does.

[rmaynard 14,922]

Just a little update. When I took the piston out, I completely forgot to measured the end gaps for the old rings, so I just went out to the shop and got the measurements:

 

Top:      .034

Middle:  .045

Oil:        .127

 

No wonder this thing was smokin'

[shallowwatersailor 3,213]

Looking good, Bob. I will be watching with interest.

[AMC RULES 36,954]

Going to polish up that connecting rod before it goes in Bob? 

[rmaynard 14,922]

Going to polish up that connecting rod before it goes in Bob? 

Nope.

[rmaynard 14,922]

Ball-honed the cylinder this morning. Came out with a nice cross-hatch. New rings fit with end gaps measurements as follows:

 

Top:       .014"

Middle:   .015"

Oil ring is a three piece which can't be measured, but it's not .127" like the old 1-piece ring.

[Fun Engineer 859]

This will be interesting. Have you found a seat yet?

[rmaynard 14,922]

This will be interesting. Have you found a seat yet?

The seat bottom portion is okay. I'm thinking of just having the back reupholstered.

[Fun Engineer 859]

I had a small worn spot on the top rear of my 857 seat. I took it to a local upholster and he removed the old damaged section and sewed a new section in its place. Not an exact match but most people would never notice. You have to look real close. Good luck Bob.

[rmaynard 14,922]

Interesting problem today. I am reassembling the innards of the engine to check tolerances,  and when I attempted to tighten the bearing plate to 115 in/lbs. as stated on the manual, the heads snapped off two of the bolts. So I went back and checked the manual and sure enough, it says 115 inch pounds. Then I looked at the heads of the bolts.

 

 

They appear to be grade 2, which have a maximum torque of 70 in/lbs.

 

Looks like I need to make a trip to the hardware store for some grade 5's.

 

Of all the bolts I have around here, you'd think I'd have four good grade 5, 1/4-20 x 1". But no.

 

Off to the hardware store.

 

 

[rmaynard 14,922]

5:30PM, back from TSC. Picked up some grade 5 bolts and I'm back to installing the bearing plate.

 

 

I started out by only installing the gasket and no shims.

 

 

The range of crankshaft end play is .002 to .023.

.002 was a no go.

 

 

 

So the bearing plate came back off and I got my pack of shims.

 

 

I decided to try 2 shims.

 

 

The result was .012. That is where I left it.

 

 

Now I am going to back up a step or two, since I did a few things without the camera nearby.

 

First, after honing the cylinder, I installed the governor thrust washer, and governor gear, cross-shaft, brass nut, and stop pin.

Then I installed the valve tappets and camshaft. The camshaft end play is adjusted by a shim or shims. With the proper shim(s) in place, the end play should measure between .005 and .010".

 

 

 

Mine measured a happy .008"

 

Before installing the camshaft and crankshaft, I use a white paint pen to highlight the timing marks on each piece.

 

 

Then, when the two are put together, I can easily see that they are properly lined up

 

 

I installed new rings and a new connecting rod. The battery in my camera died, so no pictures.

 

More later...

Edited January 16, 2014 by rmaynard

[dclarke 4,011]

Good work, Bob! 

[rmaynard 14,922]

Today is valve day. I took the block with the cam, tappets, and crankshaft installed, to the machine shop to have the valve stems ground. As you should know, the smaller K's do not have adjustable tappets, so if you grind or replace valves, the valve stems have to be ground to obtain the proper gap. Since I don't have a way to accurately grind my own valve stems, it's off to the machine shop. My shop has a policy that if you have machine work done to the engine, they will grind the valve gaps for you free of charge. I have done this on the last K161, and the K181 before. I was unpleasantly surprised today when I was presented with a bill for $47.50. Seems I didn't have any work done on this engine, so...I think I will start looking for a nice stem grinder.

 

I brought the block home and began the process that I hate most in these engine, trying to install valves with my FAT fingers. I have yet to find a simple way to install the valve keepers without having them fall off at least 10 times before I have success.

 

Anyway, just a note for the novice engine rebuilders here, read the manual...thoroughly. I made this mistake on my first rebuild, so I thought it important to point out one of things that might get overlooked.  Valve springs have an up side and a down side.

 

 

The exhaust valve and spring was installed with a few swear words intertwined with the sound of little valve keepers falling to the bench below. Finally I remembered that the last time I put a dab of oil on the inside of the keeper to hold it to the stem while I was trying to install the next one.

 

 

So after completing the exhaust, it on to the intake.

 

 

Just as much trouble with that one, but I got 'er done.

 

 

Checked my gaps. .006 on the intake, and .017 on the exhaust.

 

 

 

Ready now to start putting things back together and see if it runs again. That's a job for later. Now it time for a cup of coffee.

 

 

 

[TT-(Moderator) 1,128]

I brought the block home and began the process that I hate most in these engine, trying to install valves with my FAT fingers. I have yet to find a simple way to install the valve keepers without having them fall off at least 10 times before I have success.

4th picture up from the bottom:

[rmaynard 14,922]

 

I brought the block home and began the process that I hate most in these engine, trying to install valves with my FAT fingers. I have yet to find a simple way to install the valve keepers without having them fall off at least 10 times before I have success.

4th picture up from the bottom:

 

That stuff is sticky. Guess that's what I'll try next time. Thanks Terry.

[JERSEYHAWG / Glenn 4,487]

Bob. Looking good. Following along and enjoying as I have been tearing down the 854.

Glenn

[rmaynard 14,922]

Just a little update on my progress or lack thereof. I had to replace the bearing plate after I discovered that the threads were stripped in one of the 1/4"-20 holes in a tab for mounting the fan shroud. Thanks to Joe's OPE for a good deal and fast shipping on a replacement. Having done that, I had a good day for painting, so I applied a some paint to dress it up. Here's a couple of pictures:

 

 

 

Edited March 10, 2014 by rmaynard

[Desko 552]

Looking good rmaynard. Can't wait to see it in the tractor and thanks for sharing with us.

[Martin 2,130]

engine is looking good there Bob....

 

i use a bit of lubriplate on the keepers too. really helps hold them in place. i got a gallon tin of the stuff from work as they were throwing it out for some stupid reason. i use it on all my engines now as an assembly lube. best stuff I've ever used. just wish i could keep the dogs away from it, i can't ever put the tin down on the floor with them around, for some reason they won't leave it alone.