Paging k341 experts

[Tinkerer3 3]

Howdy all, 
I'm in the process of replacing valves on a k341 with the hope of curing a random misfire/backfire. 
This week, I got new valves from isavetractors and I have to say buying from Norman has been outstanding. 
My issue is the old intake valve has some signs of being shortened, and the new intake valve is just .002 too long with the adjuster fully lowered or atleast lowered till I hit a hard stop.

Question for the experts:
Could you remove those adjuster bolts?
What prevents those bolts from turning while the engine runs?
Can I sand that bolt head to get the extra .002 I need for .009 intake gap? 
Any ideas on what could have been done in the past that would make that lifter taller?

Thanks in advance for any info or ideas
 

[ri702bill 8,616]

My 2 cents on this....

What condition are the valve seats in?? IF they need to get dressed, that sinks the valve heads deeper and the valve will become "too long", That would require shortening the stem - either physically or in the adjuster.

Did you perform a leak down test?? @squonk recently commented in another thread  the correct way to conduct this test and the immediate answers it provides.

[Tinkerer3 3]

Thanks for the quick reply.
You're right about a leak down; it should be next on the list of to-dos. I was planning on replacing the valves since that seemed pretty cheap and easy. It also seems like a good culprit for my random miss/backfire.
The old valves sat pretty high on the valve seats, and the new exhaust valve fits fine. But that is a great point, as the length issue could be at the valve seats. 
I'll post a photo to show where the seats hit the old valves and the tappet to see if anyone thinks I can get that adjuster lower or sand it on glass. 

[ri702bill 8,616]

Not bad - seen a lot worse.

Next to check - the condition of the valve guides - wear & clearances. Both the valve stems & guides wear as the valves move up & down. There should be NO discernable "side to side rattle" in the working area.

Valve guides are replaceable but DO require reaming once installed to get the proper fit for valve clearance. NOT a pistol drill job!!

SOMETIMES - replacing the valve with an unworn NEW one in a used guide will remove just enough of that rattle to buy you time for a complete proper fix...

Edited January 13 by ri702bill

[Achto 28,062]

Personally I would shorten the valve stem. A few touches on a grinder wheel should get you where you need to be. Don't forget to lap you new valves to ensure a good seal.

 

The adjusters are an interference fit on the threads. I have never seen them back out.

Edited January 13 by Achto

[OutdoorEnvy 1,672]

Hey not meaning to doubt your work but just to double check a few things based on how you asked some questions.  '

 

Verify your engine is at top dead center with the piston at top and both valves closed completely.  They don't look even in the pic you provided and should be if it's at top dead center. 

Even though the valves are new you'll still need to seat them with valve lapping compound

The screws do appear to turn with engine running but the whole assembly turns as those are like lock nuts under them.  So it takes two wrenches to adjust these screws.  You use one to hold the lock nut part still while you tighten or loosen the screw.  It is usually pretty tight feeling. 

Also your clearance is determined with the spring and keepers installed. 

[ri702bill 8,616]

4 minutes ago, OutdoorEnvy said:

Also your clearance is determined with the spring and keepers installed. 

Yup - and DO remove all traces of lapping compound before checking!!

[Tinkerer3 3]

I found some photos of Ford Model T lifters, and it seems like the locking bolt might have a machined gap making the lower threads create more friction? Also thinking these bolts have to be hardened metal and would be very hard to sand or file? Has anyone ever removed one of those bolts?

[squonk 41,744]

Lets have a pic of the seats in the block. 

[Tinkerer3 3]

Great request I should have added one of those originally. 

[Tinkerer3 3]

Update: At TOC the intake lifter is higher than the exhaust. I'm not sure what lifter was used or why it would be a taller lifter? I do think, at this point, I'm going to take a little off the valve stem, lap my new valves, and see how it runs. 

[squonk 41,744]

Are you sure you are on the compression stroke? The intake valve will start to open as soon as the exhaust valve closes. I know of no reason to have a longer lifter. Kohler manual shows 1 part # for both lifters # D235327

[Tinkerer3 3]

Thanks for the reply. I’m 99% sure I’m measuring at TDC on compression stroke. I’ll have to see if I can make the video I made smaller for upload. 

Hopefully it is ok for me to add a bonus question can anyone tell me the correct location for the chassis ground on a C 160

with shaker mount? 

[ebinmaine 69,275]

11 hours ago, Tinkerer3 said:

Thanks for the reply. I’m 99% sure I’m measuring at TDC on compression stroke. I’ll have to see if I can make the video I made smaller for upload. 

Hopefully it is ok for me to add a bonus question can anyone tell me the correct location for the chassis ground on a C 160

with shaker mount? 

 

 

A. C160 was a solid mount so perhaps you have a C161?

 

What year?

 

 

As to ground connections... IMHO you can't have too many until the wiring looks like black/brown spaghetti.  

 

Remember these tractors are DC systems. 

Direct. Current. 

No ground is no circuit.  

 

Originally there was a wire from an engine mount to the block and frame. 

I personally add ground wires for EVERY circuit.  

 

 

[peter lena 8,933]

@Tinkerer3https://www.google.com/search?q=contractor+bolt+on+electrical+lugs&rlz=1C1CHBF_enUS866US866&oq=contractor+bolt+on+electrical+lugs+&gs_lcrp=EgZjaHJvbWUyCQgAEEUYORifBTIHCAEQIRigATIHCAIQIRigATIHCAMQIRirAjIHCAQQIRifBTIHCAUQIRifBTIHCAYQIRifBTIHCAcQIRifBTIHCAgQIRifBTIHCAkQIRifBdIBCTE5Mjc5ajBqNKgCALACAQ&sourceid=chrome&ie=UTF-8  often refer to these for  solid / simple bolt on / wire to , would also enhance the related frame / engine bolt point , for conductivity , eliminate rust / grunge , easy to use 10-12 gage wire , to insure your  grounding , never count on engine tin areas , usually rust  related . like to go from battery ground base bolt start point , verify as you go , would also move any related connection , enhance its  connection , go on , switch , connections , pete

[Tinkerer3 3]

IMG_7495.movOK, experts, I need some more ideas. 

I took .006 off the new intake valve and lapped in the new valves. The valves and seats matched up great, and so did the valve guides. I didn't have a good way to measure the guides, but they had good suction if I covered the bottom side and pulled the valve up. I also checked compression and that was great too at 125psi warm. 

Right now, I'm not sure what to check next.

So far, I have done the following:

Electrical 

• Replaced battery
• New leads

Fuel

• Cleaned tank
• New Carb from i save tractors
• Tried every combo of carb adjustment, but the default seems spot on.
• New Shut off
• New Filter 51 mic
• Removed fuel pump and fixed leaks at elbows

Ignition

• Sparkplug
• Points
• Set governor

Intake

• Replaced valves
• Lapped new valves
• Set to spec
• New air filter
   

I just ordered a coil and wire to see. I also have a cheap plastic fuel pump I will try. But I'm running out of ideas. At this point, it starts right up, but after running a few minutes, it picks up this miss / backfire more at idle. 

Here are a couple photos of the valves and a video of it running link at the top. Is there something in the bottom end that could be an issue? Any and all ideas are welcome. 
 

 

This was the first pass lapping and on the second pass there was an even better witness area. The valve and seat measured within the manual spec and the position on the valve was in the middle of the surface.

IMG_7495.mov

Edited January 19 by Tinkerer3

[oliver2-44 9,992]

Do you have the original carb?  The isave  carb probable has a throat diameter smaller than the original carb. Success with the after market carbs has beef hit and miss. 
 

Im curious how you did a compression test since the engine has an automatic compression release (ACR) at low/starter rpm. 
If you were able to do it without changing anything I would wonder if something is not right with the ACR spring/mechanism. Especially since you said the intake lifter is taller than the exhaust lifter. 
 

 

[Tinkerer3 3]

Thanks! You're clearly a K341 expert. 

Great suggestions. I had wondered about the diameter of the new carb. Let me measure the new carb and old carb. I'm not sure if the carb that came on it was original or just older. I'll try the carb to see if that helps.
 

I did not know that the motor had a ACR at low rpm. But it makes sense. I tested compression at full throttle. I'm going to have to do some research on how the ACR works and how it could affect the lifter. 

One more question, last night, I changed the oil again to take a look, and it might have had a little sparkle. It was tough to tell, and I fished a big magnet around in the oil and only got about what you would see on a magnetic drain plug in a healthy engine. 

Does it also make sense to pull the shroud and try find a timing mark on the flywheel so I can check timing? Could it be out of timing? It seems to start up and run well. At higher RPM the miss or cough is pretty random. The video I posted was at idle and probably the worst example. 

[Bill D 2,037]

Have you changed the condenser along with the points? If not, please do so.  Also, how old is the key switch?  The contacts inside could be wearing out.  If they are heating up due to the load drawn by the ignition system that could be causing your issues.  How's the rest of the wiring? Anything burnt looking or hot?  Are all connections clean and shiny? I use Noalox on all my electrical connections to aid in proper contact.  

 

Since this problem starts about 5 minutes after you start the engine, something is heating up and causing the problem.  Based on your pictures I'm not sure it was ever the valves.

Edited January 20 by Bill D

[Tinkerer3 3]

More great ideas. Maybe when I try the new coils I’ll pull the tank again and really go over the ignition switch and add a second direct ground in that area. 

[squonk 41,744]

1 hour ago, Tinkerer3 said:

 

I did not know that the motor had a ACR at low rpm. But it makes sense. I tested compression at full throttle. I'm going to have to do some research on how the ACR works and how it could affect the lifter. 
 

Your lifter was on the ACR Lever. That's why it was higher than the intake lifter. You need to adj the gap with it off of that lever

Edited January 20 by squonk

[Bill D 2,037]

2 hours ago, Tinkerer3 said:

More great ideas. Maybe when I try the new coils I’ll pull the tank again and really go over the ignition switch and add a second direct ground in that area. 

Consider changing the ignition switch with a new OEM switch, preferably a made in USA switch if you can find one.  If it's original it's 50 years old.

[Tinkerer3 3]

@squonk If I take my cam gear cover off, will I be able to tell if there is damage to the ACR lever/mechanism? If my intake lifter is always high, no matter how many times I turn the motor, how do I lower it to set the proper gap? Thanks for your other posts on this and help getting to the bottom of this problem.

[squonk 41,744]

I don't think you can see it. Can you post a video of the lifters going up and down as you rotate it? I can't think of a reason why the lifter would be high all the way around the cam unless the lifter itself was stuck. Even if the ACR spring was broken I think the ACR lever would be lower unless the spring itself was jammed under the lifter. Take the cover off. Won't hurt. 

[oliver2-44 9,992]

Like @squonk I think something is going on with your ACR. You should not be able to get 125psi compression test on that engine. I’ve gotten maybe 40-50psi on a Kohler with ACR. 

Edited January 22 by oliver2-44