Where do I start?

[txcublover]

Quick Recap: 1951 Farmall that I brought home a week ago. After taking a look at it today, I know I have multiple problems, but I need some advice on where to start. In short, I'm fairly sure:
- The carb needs work (if the shutoff is left on, gasoline leaks out the breather tube, so I assume a float is stuck at the least)
- I think the coil is bad (when the engine runs for a few minutes, it dies suddenly. It will restart 30 seconds or a minute later, but then die almost immediately)
- I'm guessing the engine needs a rebuild (I tested cylinder compression cold, then was going to repeat it with the engine heated up, but it never ran long enough to heat up. Cold, all the cylinders were between 45 and 55PSI, and while the engine is running there is smoke coming out of the dipstick tube, suggesting significant blow-by)

The interesting part to me was that the compression didn't go up with oil in the cylinders, and I would have expected it to -- though again, it was tested while cold.

In addition, my known list of issues includes:
- Rust in the gas tank.
- Generator isn't fully attached to the tractor (the belt is lose, and is apparently the wrong one, as there is no way to adjust the generator such that the belt is tight). The tractor doesn't run if one disconnects the battery while it is running.
- I have a 12 volt battery in it, as that is what the guy selling it had in it.

Questions:
Is it fair for me to anticipate that I will need to rebuild the engine given this information? (If yes, I'll start with an engine rebuild)
If that isn't a fair assumption, where do I start? I have Carb. issues and electrical issues (coil, possibly, and definitely generator and battery need to be replaced). I don't have $1000 to dump into this right now, or randomly replace parts. I was hoping to do it a bit at a time.

If the engine needs to be rebuilt, I'll have to think about how I want to do that. I have the knowledge to know what to send to a machine shop and how to put things together in a general sense (I've rebuilt small block chevy engines before), but I likely lack a few of the tools. Suggestions here are also welcome.

[raystractors]

I wouldn’t go that fast. I would clean the carburetor and check for good fuel flow. That may be why it doesn’t run for very long. Then it sounds like your valves are not adjusted. Based on the compression after adding oil. Take your time and get it running add some sea foam to the fuel and see what happens.

[ntrenn]

Agree...whoa bessie....
You have an engine that runs...yeah!!!! Now build on that. 50 psi compression typically wont start an engine so i doubt the test is accurate. Betcha got more. Leave that for later...
Engine that just dies could be ignition (coil) or fuel. Get the fuel supply consistent - especially ensure the jets are clear and the bowl is free from both trash and water....pull the pipe plug and run out a cup of fuel. Should run a stream.
Once you have fuel squared away if it still dies...swap coil out. Usually fixes spark problems but condenser and points sometimes rear their head.
Once you get her running...do a stem to stern check per the manual...

[txcublover]

Thanks -- I needed someone(s) to talk me off the ledge, so to speak. I questioned the compression numbers when I was seeing them. I will work on fuel first (possibly with some kind of donor tank initially to get the rusty tank out of the picture).

[ntrenn]

My cubs plug the main jet several times a year...takes a tiny tiny piece to plug those holes....stripped phone wire is perfect for cleaning. Ive also had my share of water accumulation in the bowl. The tractor will run until it tries to pull the water through the jet. Usually both maladies can be cured by pulling the jet and blowing it out by mouth and by draining the bowl.
Not sure why so many of these tractors 'need' rebuilding...unless they have lived the hard life. My 65 loboy was horribly abused by the po...but only HAD to have rings. No ring groove. 0.120 ring end gap. Hone and go. Rotating group was fine...tranny still needs a new 1-r slider...
Good luck with your project...it will reward you...

[Don McCombs]

Agree with taking it slow and methodical. You indicate that there is rust in the fuel tank. After you devise a pony tank, get everything clear and clean in the fuel system, from the fuel cap, all the way through to the interior of the carburetor before you determine that the coil is the culprit. Sounds like fuel starvation to me.

[Glen]

Hi,
I would adjust the valve clearance, like was said above. If nobody has adjusted them in years, some of them could be down to no clearance, and not seat closed properly.
It tells how to adjust them in the owner's manual I posted on page 1 of your other post. Here is the page below.

http://farmallcub.com/rudi_cub/www.clea ... e%2055.jpg

[Jim Becker]

Quitting due to a bad coil usually doesn't happen or recover that fast, more likely fuel. If it is electrical (check quality of spark as soon as it stops), I have seen condensers that conk out pretty quickly. Since you have only had it run briefly, all the oil smoke may be from the oil you dumped in for the wet compression test, although that wouldn't explain smoke from the breather. It takes a little time for oil in the cylinders to clear.

[Crimson Tim]

Ditto to above. I would bet the leaky needle valve and the inability to run for more that a minute or two, but then to start again within a minute are both directly related to the rust in the tank. You’ve got a bit of crud keeping the needle valve from seating and you’ve got some crud slowing fuel delivery in one or more places in the fuel line.

I had to fight this out a couple of times when I got my first. Same two symptoms.

Set up a pony tank with a clean line and clean the inlet screen at the carb, the jet, and the needle valve in the carb at minimum. Might as well clean out all the orifices in the carb while you’re in there. Just make sure to pull the two halves straight apart if this is an IH (not Zenith) carb, as there is a thin brass tube between the halves that is easily broken.

One quick test: when it starts to die, if you pull out the choke, will it run better/longer? If so, that indicates fuel starvation, which pretty well confirms a partial blockage in the fuel line.

[Eugene]

To check for faulty condenser, remove the coil wire from the distributor cap. May have to use a spark plug wire. Attach the plug wire to the coil, spark plug, ground the spark plug.

Remove the distributor cap, rotor, and dust cover. Crank engine over, observe the color of the spark across the points. Yellow spark, faulty condenser.

While there, check the points gap and condition.

[bofahs]

Take some time and read through "What to do with a Cub you just brought home" - an "enduring" post at the top of the forum.
Lots of good ideas and a great way to get your feet on the ground.
I'm not a big fan of jumping into rebuilds on engines this old - slather a bunch of Marvel Mystery Oil and get 'er running for a bit before you re-check everything. These engines were built to last under horrible conditions, and they do.
You mentioned "gas tank" - I can't say enough about POR-15's gas tank cleaner-sealer kit. I know it's not your most immediate problem, but, holy cow! that stuff is good!

[Urbish]

Take some time and read through "What to do with a Cub you just brought home" - an "enduring" post at the top of the forum.
Lots of good ideas and a great way to get your feet on the ground.
I'm not a big fan of jumping into rebuilds on engines this old - slather a bunch of Marvel Mystery Oil and get 'er running for a bit before you re-check everything. These engines were built to last under horrible conditions, and they do.
You mentioned "gas tank" - I can't say enough about POR-15's gas tank cleaner-sealer kit. I know it's not your most immediate problem, but, holy cow! that stuff is good!

to all of this. I did my Farmall H tank with POR-15 about 10 years ago and have had ZERO fuel issues since.

[txcublover]

I have read the "What to do with a Cub you just brought home", but many of those things presuppose that it is running.

Here is my planned course of action, based on the comments above:
- Disconnect the rusty tank permanently until that issue gets resolved.
- Clean the carb.
- Set up a pony tank with new fuel lines, a new fuel filter, and fresh gasoline (not sure how to do this with a gravity feed, but I'll figure it out).
- Adjust valve clearance
- Check for a faulty condenser
- Check points gap and condition (I've only ever worked on electronic ignition, so this will be fun - I may post pictures for the condition check)

At this point, if it runs, I will step through the recommended steps in the "What to do with a Cub you just brought home" thread.

I should point out that I've already stepped through parts of it -- the oil on the dipstick looks brand new, even after it ran for a few minutes, no bubbles indicating water, not insanely dark, and doesn't smell burnt as it would if it had been in there a while with the kind of blowby I saw. I've greased everything as well. I suppose I could flush the radiator before moving forward as well, but I hesitate to spend money on antifreeze if I may have to take things apart again, and I don't want to get kerosene in anyplace that needs lubricant and then forget that it is there as opposed to oil because it doesn't run for a long time (thus the original request).

[Don McCombs]

Set up a pony tank with new fuel lines, a new fuel filter, and fresh gasoline (not sure how to do this with a gravity feed, but I'll figure it out)

Make sure the in-line filter is designed for gravity flow fuel systems. Briggs & Stratton makes one.
https://www.walmart.com/ip/Briggs-and-S ... 3=&veh=sem

[k hutchins]

You mentioned possibly replacing the generator, but also said you couldn't tighten the belt. I would replace the belt first and make sure it's snug before I condemn the generator.
You didn't mention if this is a magneto/distrbutor, 6 volt or converted to 12 volt. Maybe an earlier post I haven't seen.
Check to make sure, if it was originally a 6 volt positive ground system and it's not hooked up that way now, then I have to believe that could cause problems with the generators function at this point too.