Engine rebuild

[jsfarmall]

It's very easy to sink more than it's own worth in an engine. If a block is needed the best deal I found is from jp salvage.

[Ky Cub]

PM Sent....

[Eugene]

Compression test numbers are a bit low. If the tractor were mine, I would use it as is, and wouldn't rebuild at this time.

[Glen]

Hi,
The carburetor idle mixture screw on top of the carb should make some difference in how the engine runs at low speeds.

IH used the Zenith carb on Cubs beginning in mid 1975. Below is a page from the 1975 and newer Cub owner's manual, telling how to adjust the idle screw, on the right side of the page.
It might need to be in or out a little from the 1 turn open that it says.

http://farmallcub.com/rudi_cub/www.clea ... age-34.jpg

If your Cub is a 1947, like your info says, they didn't come with a 75 lb oil pressure gauge. The gauges had no numbers, and were probably lower pressure.
The Cub service manual says the Cub engine has a 30 - 35 lb oil pressure system.
TM Tractor has oil gauges that they had made to look like the originals, they say at their website. You can look at them.
The 1st one is like a 1947 Cub had, it says.

http://www.tmtractor.com/new/en/2645fp.htm

This gauge was used later, in the mid 1950's. It has numbers, and goes to 40 lbs.

http://www.tmtractor.com/new/en/3291fp.htm

[Rick Spivey]

Ok
Oil presure stays just above mid range. My IH guage is 0-75. Mowed with it tonigh in 2nd gear up hill. It did not power down as before. Valves were adjusted at the barnyard bash couple months a go.Have ran seafoam in gas and oil. Also put some in cylinders for 2 days. Have ran about 3 hr like this.
Compression
1 80d 100w
2 70d 95w
3 75d 95w
4 75d 90w
Again thanks

With these numbers I don't think I'd be rebuilding this engine just yet. I suggest use the Cub a while as you continue to iron out the details. Every time you set something back to factory specs, the Cub will gain just a little. Also, I don't know the Zenith carb, as I don't have one. But on an IH carb, that mixture screw adjusts the air flow at low speed. So turning it out will lean the mixture out (more air), turning it in will richen it. You cannot always tell at idle when you hit the sweet spot, it takes a very good ear. But a good test of whether it is adjusted correctly or not is to "blip" the throttle from idle to full (do this at the carb, and not with the throttle lever). It should accelerate without stumbling, hesitation, or black smoke.

[Jlpb61]

Are you doing this or having someone do it?

[Eugene]

Are you doing this or having someone do it?

If you are asking about Rick Spivey, he does vitually all his own Cub work.

If that is not the answer to your question, rephrase it.

[Willy]

Has your Cub sat for a long time without running?

Mine was supposedly rebuilt in '03, sat from about '05 to 11, ran for about a half hour, then sat again until about a year ago. Last fall when I started trying to get it running again, my compression was a little lower than yours. As other things were froze up but the engine spun freely, I took a chance on the rings just being stuck and got it running before I did anything else. It was pretty smoky at first, but it's slowly clearing up. I doubt I have 10 hours on it since, but I still get a little smoke, but that most likely from the Marvel Mystery Oil I mixed in with the first fill up I did. When I first got it running, the power did seem to be down a bit, but it's came around in that department as well.

Basically, over the past year I've petted and babied it along to give it a chance to free those stuck rings up and it's running great now.

[Jlpb61]

Thanks everyone
I have decided not to rebuild at this time. I do believe it set for some years. I bought it with a bad clutch, preasure plate and piviot bearing. Previous owner hade it for a couple of weeks. Said it had been in a friends barn for years. I have run it for about 12 hours in the last year. I have read on this forum that heavier oil will stop the smoking. If so does it help with the compression? Witch is better 20/50 or 15/45? Opinnions?
Souns like I need to put it to work. Anyother ideas are appreciated.

[Glen]

Hi,
If the engine smokes, and it is bluish smoke from oil burning, the people on here have said that an oil additive can help.
I have had success using Rislone before. Run the engine for several hours, making it work doing something. The people on here say other brands of additives work too.
The additives can help loosen stuck piston rings. If the rings are wornout, then it probably won't improve.