1941 9n misses in the high RPM's when NOT under load

9nericm

New User
Hello, I'm a newbie to the group and the n series tractors and have a unique issue. Also, I apologize for the long post.

While bush hogging in low range 2nd gear 3/4 throttle my 9n will plug along just fine and never miss a bit when I'm going thru heavy grass or uphill causing a load on the engine and the governor will add fuel and hold it if need be to if it starts to bog down. When I'm free wheeling going down grade or short grass it will act like it's starving for fuel at times slightly missing. I've checked fuel flow, cleaned fuel tank, cleaned sediment bowl and screen, cleaned carb and adjusted it lean/rich/just right, made sure I've got good spark, set plugs to proper gap, replaced intake gaskets, checked compression, made sure all my lifters and valves are set and working correctly and done everything I can think of. Anyone else ever had this issue? One thing I have noticed is I can see it blowing compression around plugs by spraying a little wd 40 around them before starting it up. I'm afraid to over tighten but they are definitely snug.

-1941 9n Ford Tractor Sherman Step Up
-MID 90's PSI Compression all cylinders
-Holds Great Oil Pressure
-12 Volt Conversion with Dragon Fire Electronic Ignition,Dragon Fire Plug Wires and Dragon Fire Coil. Autolite 437's and tried Autolite 216's
- New Zenith Carburetor (I also have a new TSX 33 in box does same thing)
-Replaced Starter Switch, Resistor Assembly, Ignition Switch, New Battery, New Wiring Harness to everything
-Added the spin on oil filter adapter
- New Governor (Off Ebay though for around $250)
- Vertical Exhaust no muffler[/u]
 
Something is wrong if you are leaking around the spark plugs, tighten them down.

Is governor cutting things out when not under load and maybe carb is a bit rich too?
 
9nericm ,Like 6 sly said Check the mechanical advance in the distributor for broken springs,worn slots causing it to hang up.Also
try setting spark plug gap to .030 instead of .025 with Dragon Fire Electronic Ignition.Torque the plugs down tight say 25-30 foot pounds.You say the governor is working properly,Is the air cleaner clean wire inside not clogged with dirt.Try adding a little choke when it starts missing and see what that does.

This post was edited by Den N Ms on 09/20/2022 at 07:40 am.
 
Thank you all for the suggestions!

I have checked the oil bath and it has
always been clean.

I had been leaning toward it being an
issue with the governor but I ran the
tractor with it unhooked and when I held
it in the high rpm's setting still with
no load and it still had the miss issue
so that made me think something else.

The distributor is newer as well but I
could definitely see the springs or
counterweight dogs causing the issue.

I'll also try setting the gap to .30 and
torque them down to 30 lbs because I know
I'm nowhere close to that tight. I was
afraid of stripping them out. On I side
note I even indexed the plugs once like
on our racecars but that didn't help
either haha!

I have to say I really like these old
tractors though. The simplicity and
versatility are great for people like
myself. My uncle bought a completely
restored 8n and after using it and tuning
it up for him after his forst mowing
season I had to get one for myself.
 

I apologize for the delay but I finally got the new distributor on last night getting ready for garden season this year and it cured all symptoms. Tractor runs like a top again so thank you all for the help!
 

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