Farmall H Engine Specs

I have a Farmall H that had the engine stuck when I dragged it home. Got the head off and things aren't looking too bad. Looked all over for Engine specs on the internet, like how large the cyl bore can be before resleeving or ring gap, rod bearing gaps. I can find nothing online. Anyone have any idea where to find this information?

There is a website dedicated to the Farmall H tractor with the address of www dot farmall-h dot com which contains all the basic specifications for the tractor. What you are asking about are unique specifications that are probably not noted but someone who rebuilds engines will be able to provide with more detail. Any competent engine rebuilder in your local area (or those on this forum like Janicholson can advise with what you are asking) would be able to make accurate measurements and advise what actions would be required in your specific case. Good luck in your endeavor which will provide much enjoyment, Hal.

The need to replace the cylinders and pistons can be measured well enough to make a decision as follows:
The top 1/2" of the cylinder bore is usually unworn. It will be covered in carbon or deposits, and must be clean to continue.
Use a box cutter to scrape the metal to remove most of the deposits. Then use 240 or close to 240 grit silicon carbide paper to polish it shiny. Do not remove sleeve material while doing this, just get it shiny around the top.
Tool
Get a 4-1/2" piece of 1/4" ready rod (threaded rod) or a 4-1/2" X 1/4" (or 6mm metric) bolt, and two nuts. If a bolt, cut the head off just under the head. dress one end with a file to make it smooth and flat. Buy (or find) two nuts to fit the threads (fine or course or metric threads is not important.
With this threaded rod in hand, place it across the top of the cylinder with one end just touching the top inside of the cylinder.
Mark the basic diameter on the rod where it touches the opposite side. Be careful to keep the mark close to the exact diameter. cut the rod so it just fits across with a tiny bit of play.

Put the nuts on the rod at one end.

Use the nut closest to the end to adjust the rod to fit across the cylinder. Make sure the nut is positioned so the flats of the nut are up and down in the bore so it is nested as far against the sleeve as possible. Now run the other nut against the first to jam them and lock the "measurement". This is now used below the top ring wear stopping point to measure the wear. The top ring is least lubricated and has both heat and pressure applied. Thus the most worn. Using a feeler gauge (narrow 1/4" width) take it apart to get each blade separate. or buy separate feelers from .001" to .008". Use these to fit between the end of the rod and the widest point of the cylinder worn location.
Be careful to measure on a diameter, with the nut flats aligned, and level across the bore.
The tool can be used with a dial or digital caliper. If that is used, the second measurement can be made by adjusting the nuts as before but down in the wear zone.
If the cylinder measures less than .002" bigger in the ring wear zone, I would put it together as is. If between .003 and .005 Still usable if money is an issue and getting some service out of it is important. Bigger than 6 really needs new sleeves and pistons.
The measurement method above is very accurate, but it does not indicate ring wear, or condition of the bearings on the crank or cam. Good luck. Jim

Thanks for the information. I have been to farmall-h.com and they have good information...just not engine tolerances.

janicholson...thank you for the in depth information. I am already past the point of being able to use that method. I ridge reamed the top, pulled the pistons and honed the walls to remove any crud (very minimal) from the pistons being stuck and so I could get good measurements. I now have no reference at the top to use your numbers. I was hoping to find a min max bore size. I have telescoping gauges and micrometers or calipers I can use, just no tolerance numbers to go by. Think I'm going to have to wait on a manual. Say bye to the warm January weather. I have no shop to work in. Brrrrr. lol

Put ISS-1039-1 into Google, it will tell you where to find all you will ever know about gas 4 cylinder engines.

The bore at the very bottom is also considered to be as new. Measuring there is fine using that method, or real telescopic bore gauges, or a pro level digital bore gauge. Stay within a half inch of the bottom and square across the bore as well as level. It will work. Jim