Sooty plugs, no smoke

The Cub Club -- Questions and answers to all of your Cub related issues.
Forum rules
Notice: For sale and wanted posts are not allowed in this forum. Please use our free classifieds or one of our site sponsors for your tractor and parts needs.
TonyTractor
Cub Star
Cub Star
Posts: 63
Joined: Fri Feb 22, 2019 11:04 am
Zip Code: 12444
Tractors Owned: 1948 Cub
1981 Simplicity 7117 Hydro
2009 John Deere LA105 (family/friends can help mow)

Sooty plugs, no smoke

Postby TonyTractor » Wed May 06, 2020 8:39 am

Searched the many posts on sooty plugs. Seems like it could be caused by several things.

I'll start with some history: Rebuilt the carburetor last month, it was leaking pretty bad on the '48 because of float or needle or both. Cleaned soot off the plugs which was very thin. No oil residue. I read the manual for info on carburetor settings, but not sure if I have it exactly right. It does not leak unless I try too many cranks, which I do not do anymore.

I tuned it up last year after I bought it. New copper wires, new auto-lite 3116 plugs, points, cap & rotor, also static timed it. Changed the oil (rotella 15-40 diesel ) & filter twice in a year. First change was pretty bad, previous owner did not change it for what looked like years, very tar like. Oil pressure looks fine. I have not done a compression test as I do not have a gauge yet. Cleaned the air filter cap & pipe & changed that oil too. Replaced the exhaust manifold when I got it because the old one had zero threads. It didn't have a muffler when I got it. No bucket or rain cap either,
:(

So after I rebuilt the carburetor & cleaned the plugs it started up fine. Took a road trip through all gears. Runs fine even up some steep grades, elevation is about 2,000 ft around here. It actually seems to produce more power (torque?) ) going up grades. I did notice soot blowing back down the TSC muffler along the exhaust stack onto the hood. Not much but enough to cause concern. Next day it would not start. Cleaned the plugs, again with thin coating of soot. Started on first crank.


Have not checked the points or plug gap but will try that today. I have not tried Seafoam yet. Thank's
#1 rule of tractor maintenance or repair: a tractor is not a car.

User avatar
Urbish
5+ Years
5+ Years
Posts: 2295
Joined: Sat Sep 07, 2013 3:45 pm
Zip Code: 48158
Tractors Owned: ~
1958 International Cub LoBoy
1948 Farmall Cub
1977 International LoBoy 184
1947 Farmall H
1946 Farmall B
1953 Willys CJ3B

Cub-193 Moldboard Plow
Cub-54A Leveling and Grader Blade
Cub Loboy L-54 Leveling and Grader Blade
Unknown 5' Single Gang Disc Harrow
Circle of Safety: Y
Location: Manchester, MI

Re: Sooty plugs, no smoke

Postby Urbish » Wed May 06, 2020 9:49 am

I would say wet and dry compression tests are required to eliminate that as a problem. Low compression will result in an incomplete burn and leave soot. I have a cheap Harbor Freight compression tester set and it works great. If you're not familiar with wet and dry compression tests, just do a search on this site as it has been covered many times.
Jim

Circle of Safety

inairam
5+ Years
5+ Years
Posts: 2286
Joined: Wed Jul 08, 2015 10:24 am
Zip Code: 19342
Tractors Owned: 1948 6v - Dozer
1949 with kub klipper belly mower. mag 6v - Mom
1950 with plow, 54 blade, mott mag 6v - Roxanne
1953 54 blade, c22, wood 42 6v
1957 6v - barn Queen
1965 lo-boy with c-3 mower 12 v - Loboy
1974 Horse II 12 v c-2
1975 with woods 42-6 12 v - Horse
1979 long strip 12 v stuck engine
130 with international 1000 loader 6 v
1969 140 with bush hog tow behind mower 12 v
Terramite T-6 4WD Backhoe Perkins diesel
Memberships: Rough and Tumble Engineers Historical Association;Chapter 8 IH Collectors; IH Collectors Worldwide
Circle of Safety: Y
Location: Glen Mills PA

Re: Sooty plugs, no smoke

Postby inairam » Wed May 06, 2020 10:48 am

Maybe running rich.
When you only have 9 horsepower you need to know the names of all of the ponies!

outdoors4evr
10+ Years
10+ Years
Posts: 2664
Joined: Tue Jul 22, 2008 12:44 pm
Zip Code: 48370
Tractors Owned: 184
Location: Oxford, MI

Re: Sooty plugs, no smoke

Postby outdoors4evr » Wed May 06, 2020 1:19 pm

1) Verify carburetor float settings.
2) Run hotter plugs. The 3116 plug is recommended for light duty use. If you want to stick with Autolite brand, the Autolite 376 is the cross reference to the Champion D21 plugs.
184 w/ Creeper & 3-Point
IH 3160a Mower
IH Model 15 Tiller
IH-54 Blade

TonyTractor
Cub Star
Cub Star
Posts: 63
Joined: Fri Feb 22, 2019 11:04 am
Zip Code: 12444
Tractors Owned: 1948 Cub
1981 Simplicity 7117 Hydro
2009 John Deere LA105 (family/friends can help mow)

Re: Sooty plugs, no smoke

Postby TonyTractor » Wed May 06, 2020 4:40 pm

Thanks guys, I appreciate your time. it's great to learn something new every day.
#1 rule of tractor maintenance or repair: a tractor is not a car.


  • Similar Topics
    Replies
    Views
    Last post

Return to “Farmall Cub”

Who is online

Users browsing this forum: Glen and 0 guests