Jump to content

Farmall M running rough


Recommended Posts

 Hey guys,

My great grandfathers farmall M hasn’t been ran since 1995 and a buddy and I have recently resurrected the old girl. I have attached a YouTube video link for you guys to look at and see if you could tell me why she is refusing to run like a champ. We have done the following: Brand new spark plugs, wires, completely rebuilt magneto by Brillman Co., and completely cleaned and gone through carb. 
 

https://youtube.com/shorts/OoaZroZKy2U?feature=share
 

Thanks!

Link to comment
Share on other sites

I didn't try to watch video, as I can't get service at the moment, but what's the compression at? I'd want at least 90 go even make it try to run. Getting lower than that and it's going to be difficult. 

What is your timing at? I think there is a different timing mark for the magneto, but an old timer will have to correct me on that...

What kind of wires did you use? 12v coils don't usually have the trouble of modern style carbon core wires, but mags sometimes don't have enough umph to get the spark to the plugs. They usually use copper core wires.

  • Like 1
Link to comment
Share on other sites

Magneto should be set so it trips at 5* past TDC. That would be the second of the two  close together marks on the pulley if its the original pulley. Magneto's do like copper plug wires, they don't make a good spark with modern wires. This was the case of my 48 H when I bought it; fella said no matter what he couldn't get it to run well. After a few minutes it would run roughly with an intermittent miss. A set of good copper wires and she runs great!

Link to comment
Share on other sites

As said check the timing and make sure you have good copper wires.    Also check to make sure all valves are free and check for bent push rods and valve ajustment is correct.   Good luck.

Link to comment
Share on other sites

check the compression first and record it. set the valves to spec.( .017) . then recheck the compression.   a valve set is part of a major tune up.  as said the wires MUST be the wire core not carbon core.  plus the timing has to be set to spec.  it sure sounds like an exhaust flutter. plus you set the carb after the timing set, NOT before.  open the main jet on the bottom 3-4 turns open at 5 turns the needle will be fully out of the seat for heavy pulling. set the mixture screw at 3/4 turn out. idle screw is 400 rpm. tractor should be starting with 1/2 a revolution crank, meaning when 1 cyl fires it should be running.

Link to comment
Share on other sites

Also, little trick I seen an old self taught mechanic do, get engine up to as high of a rev as it will get, then, quickly kill the spark. As the engine comes down to a rest, you can hear the chuff out the exhaust much easier, or out the carb if you have the air cleaner tube off. 

Link to comment
Share on other sites

Ok guys,

thanks for all the suggestions. I’m going to replace my wires, get a compression tester, set all the valves and then see where I’m at. I’ll check back in a week or so after we get that figured out and see where I’m at.

Thanks again,

Phil 

Link to comment
Share on other sites

I'd also check for vacuum leaks between the manifold and the head. Spray starting fluid where the manifold and head connect. Should smooth out if there's a leak. Sometimes tightening the manifold bolts will fix it. Do the same thing at the carburetor gasket. 

Link to comment
Share on other sites

14 hours ago, FarmerFixEmUp said:

I'd also check for vacuum leaks between the manifold and the head. Spray starting fluid where the manifold and head connect. Should smooth out if there's a leak. Sometimes tightening the manifold bolts will fix it. Do the same thing at the carburetor gasket. 

Okay I’ll check that out as well thanks for the suggestion. 

Link to comment
Share on other sites

https://youtube.com/shorts/Hc9VwfhR2i4?feature=share

Well guys, she is finally running correctly. We checked the valves, they ALL needed adjustment. Then we started looking over the book (the original book I might add, super cool that my great grandpa kept it) and we noticed that we actually had spark plug wires mixed up, we fixed that (which was a stupid issue to have we should have seen that but whatever) and we rotated the rotor 180 degrees because it fired on exhaust, gave it another tug and she took off like a rocket. 
 

thanks for the help,

Phil 

  • Like 4
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...