Farmall H Engine Rebuild

Hi All,

I am looking into rebuilding the engine on my H. I did a little bit of research and found the stock bore on a H was 3.375, the bore on a Super H was 3.5, and the bore on a 300 was 3.5625. Would it be an easier swap to put the pistons and sleeves from a Super H in it or from a 300?

Also, if bored to a Super H or 300, would I have to do any other modifications (head, intake/exhaust mods) to get her to run her best.

Any information to help me out would be appreciated.

-apz*jr

Well the engine is sleeved. (dry sleeves) if you remove the existing sleeves thinner sleeves can be installed. It will not quite get to the SH dimension, but with higher compression domed pistons it will be more powerful than a stock SH. All other efforts will require boring out the cylinder block to larger diameters for bigger sleeves, or running with no sleeves. Putting a 350 engine block in it and using thinnest sleeves in that with high compression pistons (and its cam carb intake and distributor is about as powerful as you can get without compromising farm use or getting carried away with making a puller only. Jim

How much bigger depends on what kind of chance you want to take on the cylinder wall getting to thin. Without going to special made pistons you have a few choices.
Use 3.5625 pistons and sleeves for a SH and bore the H block about .125. That gives you 169 CI. Use 3.625 pistons and bore to use the pistons without sleeves. 175 CI. If the sleeveless bore in the H block is good and you can get the correct cylinder wall to piston clearance the 3.5625 pistons can be put in a H without useing sleeves. To use 3.625 pistons with sleeves the H needs bored to around 3.750. Some won't do it without problems.
If the tractor is going to be used other than pulling and you decide to bore. Think about the 3.625 on the block. Then if another rebuild is ever wanted bore just a little and install 3-9/16 pistons and sleeves for a SH. Or if they work for your block use 3.562 pistons without sleeves, then the sleeves for 3.562 pistons in a SH if the bore wears out. Or bore again to use the 3.625 pistons.
Don't know what cylinder head you have but some pistons for the bigger bore will contact a H head unless the head chamber edge is rounded a little. Filler rings or special head gasket maybe needed for some combinations.
Also if any machine work is done the parts that are to be used size is needed, or better the parts on hand and measured.
Block bores without sleeves will measure around these numbers or a little larger. H block 3.5625, C-164-3.6875, C-169 and C175- 3.749.

You can install a new sleeve kit with 3-7/16" pistons. No machining required for the new kit.Hal