K161 Valve Guide

[rmaynard 15,444]

Helping my 13 year old grandson with his 701 today. While he spent the day sandblasting and priming rims, I worked on the engine. Having already found that the engine must have been run without oil, (broken rod, worn out governor gear stud, and other evidence), I now have a problem with the exhaust valve guide. It's at the point where the valve moves about 1mm side to side. I can't really imagine leaving it that way without more damage or at least poor running.

 

Has anyone replace a guide in a K161 or K181? Is it something that I can do in my shop with basis tools, or am I in line for a run to the machine shop?

[WHX?? 48,815]

Personally I would take it to a shop Bob. Make sure it's done right. Thats If you can find a reputable shop. I know I can't do it from a hobbist stand point. Trusting your boy is in on the decision making in order to educate him. 

[ri702bill 8,316]

It is my understanding that once installed, the ID needs to be reamed open a bit for proper valve stem clearance - that needs to done in a drill press or milling machine to ensure proper alignment so the valve shuts squarely.

What about the intake guide - probably only a few dollars more to do both??

[rmaynard 15,444]

1 hour ago, ri702bill said:

It is my understanding that once installed, the ID needs to be reamed open a bit for proper valve stem clearance - that needs to done in a drill press or milling machine to ensure proper alignment so the valve shuts squarely.

What about the intake guide - probably only a few dollars more to do both??

I read that in the manual too. Intake valve guide is good. 

If it has to go to a machine shop, they are going to tell me that the cylinder needs to be re-bored since there is some scoring. That will require going with a whole new piston and rings since this is an older block with the 2-7/8" piston that is no longer available. I'm not sure where that will lead.

[ri702bill 8,316]

Early block, probably 1962 or 63 before the 8 hp engines came out and they shared the larger bore - I believe that yours can be sucessfully bored to the 2-15/16 bore....

Bill

Edited July 12, 2022 by ri702bill

[Pullstart 62,843]

Seems like I popped some out before, maybe with a slide hammer?  I can’t recall the rest of the job…

[squonk 41,090]

Guides are popped out with a slide hammer. Installed with a stepped tool and a press. Then reamed to size with a piloted reamer.

 

Take it to a machine shop. If he doesn't have to warranty anything he will probably overlook your tore up bore and take your cash. When they have to guarantee their work is when they get fussy.

[richmondred01 2,237]

I have a tool that I made that I’ve been using for years. 
I knock them out and then, put the new guide in the freezer overnight, and knock the new one in.

Once installed they must be reamed to fit the stem. 
I never use a “press” because I’ve seen twice when using a press caused the the block to crack. 
Needless to say, the cam must be removed as well as the tappets.
Ive done hundreds of guides this way and never had an issue.

All the best.

Edited July 13, 2022 by richmondred01

[richmondred01 2,237]

Any issues with your machine shop, run the block down to me and I’ll knock out your old one and install a new one. 
It takes about 5 minutes. 
You can carry it back to your machinist and he can do the rest.

 

[rmaynard 15,444]

5 hours ago, richmondred01 said:

Any issues with your machine shop, run the block down to me and I’ll knock out your old one and install a new one. 
It takes about 5 minutes. 
You can carry it back to your machinist and he can do the rest.

 

I thought about doing just that, but...the cost of gas to get there and back is prohibitive. 

[richmondred01 2,237]

The offer is there if you plan on passing through just give me a heads up. 
 

[rmaynard 15,444]

3 hours ago, richmondred01 said:

The offer is there if you plan on passing through just give me a heads up. 
 

I'll be headed south in less than a month, but I'll be in a 737. 

[Jeff-C175 7,202]

4 minutes ago, rmaynard said:

I'll be headed south in less than a month, but I'll be in a 737. 

 

Maybe the captain will let you throw it out with a parachute?

 

 

[rmaynard 15,444]

So I dropped off the K161 block at the machine shop today. Even more bad news. The piston that I have from the old K181 looks great, but it is out of round. New piston and rings on the way. The crankshaft needs to be turned to -.010, and I need a new +.010 rod.

 

This grandson/granddad project is going south real fast.  

[richmondred01 2,237]

Better to know now.

all the best with your project.

[rmaynard 15,444]

Picked up the K161 from the machine shop today. Bored to 2-15/16", valve guides replaced, valves ground, crankshaft turned to .010 under. Total damages for shop work $326.05.

[richmondred01 2,237]

Do you have the two part cam?
 

[rmaynard 15,444]

56 minutes ago, richmondred01 said:

Do you have the two part cam?
 

Yes, but I'm replacing it with an ACR cam.

 

[richmondred01 2,237]

29 minutes ago, rmaynard said:

Yes, but I'm replacing it with an ACR cam.

 

Remember to replace the valve tappets too. They are different.

[rmaynard 15,444]

27 minutes ago, richmondred01 said:

Remember to replace the valve tappets too. They are different.

When I put the tappets in from the K181, the exhaust was way too long. I would have had to grind way too much off of the valve stem to get .017 clearance. With the K161 tappet I still need to grind. 

[Gregor 4,846]

Anyone have any idea what it would cost to ship a K161T from IL to MD ?

[squonk 41,090]

I noticed on Brian Miller's site he has the dimensions of the tappets backwards in his picture. 

 

The ACR tappet is 232777-S but in his description he has the length as 1.964" 

 

Valve Lifter/Tappet. Fits later Kohler engine models K141, K160/K161, K181, L161, L181 and M8. For use with intake or exhaust valve and one-piece camshaft with automatic compression release (ACR). Replace worn lifter to prevent erratic valve action and/or premature cam lobe wear. Non-adjustable. Grind end of valve stems with piston positioned at TDC on compression stroke to set valve clearances. Dimensions: 1.964" overall length x 1.115" base diameter x .308" stem diameter. Discontinued Kohler part # 232777-S.

 

That's where the confusion on proper length must have come from.

[rmaynard 15,444]

I have reassembled the K161 using the ACR cam. I had to use a short (1.96) tappet for both the exhaust and the intake. I have yet to figure out why my K181 doner had a 2.03 tappet for the intake.

Here's the thing. A new exhaust valve (230710) is 4.063 long. 

 

The exhaust valve from the K181 is 4.0315.

 

The exhaust valve from the K161 is 4.0110

 

The 2.03 tappet would be much to long, even for the shortest of the valves, whether exhaust or intake, requiring excessive grinding of the stems for proper clearance.

 

With the shorter tappets installed, and the exhaust valve stem ground to 4.011, I have a clearance of 0.017.

 

 

Edited July 28, 2022 by rmaynard

[squonk 41,090]

The only difference is the cam.Block height is the same. The longer tappet would probably work fine with the 2 piece spark advance cam. Valves should be the same length no matter a 161 or a 181 until the stems are ground. 

[rmaynard 15,444]

Well, today was the day see what all my engine changes did for me. First of all, I wanted to see how the engine turned over with just one belt.

The belt us just tight enough to turn the engine without slipping. After this picture, I move the belt to the inner pulley thinking it would put less strain on the starter bearing.

 

I hooked up a temporary fuel tank, primed the carburetor, and applied power to the starter. The engine turned over without effort (as I expected it to), and ran like a top. 

 

 

So, I don't know what if anything I accomplished by installing the ACR cam other than proving that it's easy, allows you to do static timing, and saves one V-belt.

 

 

Edited April 6, 2023 by rmaynard