Good question

grandpa Love

Well-known Member

• Aug 18, 2021

• #1

Why do some of our tractors have to warm up a couple minutes before you can drive them? If you try to put them in gear and drive,they die. Others will crank up and go. Also why do some tractors need choke to start and others don't? I call this continuing education!

 

R

rrlund

Well-known Member

• Aug 18, 2021

• #1

I can tell you right now, you've choked that purple one too long.

 

Geo-TH,In

Well-known Member

• Aug 18, 2021

• #1

GP,
I'm 72 and grew up with cars with auto choke. That made fuel mix richer, which is needed when engine is cold,

I have the carb on 1950 Farmall and Jubiee leaned out.
They require a little choke until they warm up.

I'm betting the computer on fuel injected cars monitor air temp and water temp and adjust fuel mix. Also computer moniters exhaust O2.

If you have tractors that run fine when cold, check out the spark plugs, I guessing they will be black instead of clean..
It's possible rich carbs may wash oil off cylinder walls and give you a puff of white smoke when they start.


I'm a shade tree mechanic, no expert. Just my opinion.

 

R

Russ from MN

Well-known Member

Location

Bemidji MN

• Aug 18, 2021

• #1

It depends on how the carburetor is designed and adjusted.

 

OP

OP

grandpa Love

Well-known Member

• Aug 18, 2021

• #1

rrlund....it appears so! Lol

 

OP

OP

grandpa Love

Well-known Member

• Aug 18, 2021

• #1

So choke is good??

 

D

Determined

Well-known Member

• Aug 18, 2021

• #1

Intake manifold leaks that close up as metal warms and expands.

Carburetor with worn out throttle shaft bores and or plugged up just enough that it will still run fair when warm but will not deliver enough fuel when cold without the help of the choke.

Low compression that improves slightly when engine warms up.

Valves out of adjustment.

Worn valve guides letting oil into cylinders lightly fouling one or more spark plugs, not all of them fire properly until the engine warms up.

The list goes on and on.

 

M

Moonlite37

Well-known Member

• Aug 18, 2021

• #1

The adjustment and design of the carburetor are also valid considerations, but the design of the intake manifold would also play a big part. When young I worked on a farm with a IHC 300 utility and that thing would rake about a half hour to run right without choke, but warned uo, it was a pulling beast

 

greenmech

Well-known Member

Location

Lakeville MN

• Aug 18, 2021

• #1

Just a question, how would you like to wake up and then have to run 5 miles without warming up? Ron MN

 

Geo-TH,In

Well-known Member

• Aug 18, 2021

• #1

Cold engines with a lean carb needs choke to richen up mix and start.
I have to use choke to start all my lawn mowers.
If engine requires choke all the time, your carb needs cleaned.
IF you don't need choke on a cold engine, I'm guessing carb is too rich.
No choke is required once engine warms up.
Just my experience.
Some carbs are backwards. Carb on farmall has one adjustment. If you screw the adjustment in, you richen the mix. Most carbs is the opposite. Fords have 2 adjustments. One screw is like Farmall in to richen mix. The big adjust is normal, in to lean.

 

Janicholson

Well-known Member

• Aug 18, 2021

• #1

Those that wakeup ready to go probably are running rich. It could be from float level too high, idle adjustment too rich, main jet too big. The ones that take a long time are lean. Float level too low, adjusted lean, small jets, or intake vacuum leak! Cub carbs generally don't have high speed mixture control, so have limited adjustability from outside the carb. Jim

 

S

Steve@Advance

Well-known Member

• Aug 18, 2021

• #1

It's called 'personality'!

But compression is a big part of it. A sick engine will show more symptoms cold and at idle.

Carburetor has a lot to do with it. Though they may look the same on the outside, there are small differences on the inside, idle jet size, air bleed jets, who knows what has been done, swapped, drilled, mix matched, partial clogs... Float level is a big factor.

Have you gone through the air cleaners? The wire mesh gets clogged and has to come apart to clean it properly. Contrary to popular belief, a clogged air cleaner can actually lean an engine. A properly working and designed carb will only look at air flow, not air restriction. Closing the choke is not the same as restricting the total air flow.

 

L

larry@stinescorner

Well-known Member

• Aug 18, 2021

• #1

The one on the right,,is my Cub,,hows it start?,so I know what to do,,what it likes,,etc

 

R

Richard G.

Well-known Member

• Aug 18, 2021

• #1

Kevin, my 8N has to have a the choke pulled to crank cold and when hot.
It runs great after about 30 seconds when cold.
When hot I pull the choke and as soon as it fires up I push it in.
Every tractor is different.
Richard

 

O

old

Well-known Member

Location

Camdenton Missouri

• Aug 18, 2021

• #1

It has to do with many factors. Carbs being just right. Timing being just right and then condition of the engine. Some of my tractor can be a pain to start while one like my Oliver S88 starts so easy that you almost can't get you hand off the starter button fast enough

 

Geo-TH,In

Well-known Member

• Aug 18, 2021

• #1

Steve,
Physics 101, compress air and it gets hotter. It's called the ideal gas law. Good law, Supreme court has never over ruled it, yet.
That's how diesels work with no spark. Compression ignition which Rudolf Diesel used to make the diesel engine.
Gas engines also need warm air for good combustion.
So yes, good compression is necessary, especially when it gets colder.

 

J

James Howell

Well-known Member

• Aug 18, 2021

• #1

[b:654c4848f0][i:654c4848f0]wake up and then have to run 5 miles without warming up[/i:654c4848f0][/b:654c4848f0]

The undertaker would find me at the end of the driveway near the mailbox.

 

Stroby

Member

• Aug 18, 2021

• #1

I call it harassment of the elderly.....

 

D

Danny Prosser

Member

• Aug 19, 2021

• #1

Because they're old engines and no two are the same the same way old cars and trucks were. You just have to find the right combination for each one. For example I had a 69 truck that you just hit the switch and didn't do anything else didn't matter what the temp was. I had a 59 model you pumped the gas pedal 2 times and let off and hit the switch. We had car I forget which one you had to hold the pedal down until it cranked. That's all just part of the fun of having tractor fever is figuring out what each one likes and don't like!