Bringing a 640 Back To Life (was Newcomer)

[tderrick]

Thanks, brother... I think it's going to be a good one.

I really appreciate all your expertise! The part# stuff is coming in very
handy.

Will keep all posted.
I think I may be close to firing it up this weekend...

 

[tderrick]

Looks like I need to rebuild the carb... any suggestions on a good kit??

 

[Soundguy]

Tisco makes a kit, ( can be had at some TSC stores, or ordered from a tisco dealer ) and you can also get a kit from napa, or from CNH.

most kits do not come with the float, so if you need a float, it will need to be ordered sepperately. Also.. most places sell a basic and an advanced kit. The advanced kit usually has replacement needles and other goodies.. I like the advances kits.

You will need to know if you have the zenith, or the MS carb.

I like to get carb parts here as they have a good variety of what parts / kits to get:

Discount Tractor Parts and Manuals for Older and Antique Tractors

soundguy

 

[tderrick]

update...

the motor barred over perfectly after the pistons were soaked in
ATF for a few days.

Alternator and battery are in... Starter works perfectly.

Re-building the carb at the time of this post. Cleaning major sludge
out of the gas tank.

Radiator appears ok. No leaks at present.

Installed all of the NAPA ignition parts suggested by Soundguy.



I have one question about the electrical wiring as I'm going through it...

There is a wire coming off the terminal block (hot ,fused) going to the pull out light switch .
At the switch (hot side) it is factory combined with another wire that goes off to the harness. Where does this hot wire go?

I have a big voltage loss at the headlights and I'm trying to track it down.

 

[Soundguy]

It's likely that that wire ran to a rear lamp that has/had it's own switch.

Most problems with lamp circuits are grounds.. IE.. there is a hot wire run tot he lamp, and then the lamp sheel is bolted tot he painted sheet metal, and then add in 50 ys of rust, and the rusty sheet metal is bolted tot he painted frame.

I run a seperate ground wire to the base of all my lamps to get away from sheet metal grounding.

soundguy

 

[tderrick]

Thanks, brother.... I thought it might be going to a switched light. I'll look
deeper...

and run some separate grounds.


Should be cranking it up in a week or so...

 

[tderrick]

update...


I disconnected the mystery wire from the hot side of the light switch and
now the headlights are at full strength.

The carb is rebuilt and in. Boy, the main adjustment needle was really
frozen in there... I guess from the old gas just sitting in there and gumming
it up. A little PB and some patience and it was out.

Fresh oil in...

Almost ready to fire...

 

[tderrick]

It's Alive!!

The motor fired right up and sounds great!
The ammeter went up to about 20, the oil pressure went right up to over 60
and is perfectly stable.

I reversed the direction of the magnetic type ammeter and just like I
thought, it moved in the correct direction. (difference between pos. and
neg. ground?)

Temperture gauge is working.

Now for the bad news... It will only run for a little while. Like just enough
to dry out the bowl, then after a while...(as the bowl fills up?) It will start
right up, runs great and dies at just about the same time.

I'm wondering if I messed the carb rebuild up or if a piece of crud is blocking the main jet or something.

I put about a half a tank of gas in, so it should have enough pressure...

I also have a small leak at the tank valve.


Any ideas before I dig into the carb again?


btw the 8N is back and the steering is better than my '66 mustang!

 

[tderrick]

Good news... readjusted the floats and I'm good to go.

A few carb adjustments and it was running perfectly.

Hydraulics are working.

Took it for a spin around the farm and I think all is well.

Just a few questions left...

Will Napa have the replacement fuel tank petcock to fix that leak?

And the radiator never got a good rush of coolant in the radiator but it always
ran cool. About 1/3 of the gauge. Is that normal for this tractor? My 8N rocks pretty hard in the radiator...

Boy... I'm almost ready to put this thing in service!

 

[wolc123]

Close the gas valve and remove the gas line from the carb. Open the valve and see if you have flow. If you do not, then there is probably crud built up in the bottom of the tank that is blocking flow. If that is the case, you will want to remove the tank and clean it out good. Glad to hear you got the 8n back in service. I still want to know which one you like better when they are both going.