Thoughts on H rebuild/performance

[j_w_ander]

I'm looking for ideas or thoughts on what route to take when I rebuild my early ('41)straight H prior to painting. It is unmodified/gas only and runs superbly at any RPM, but there's a little blue smoke it's always had since my dad bought it from his cousin in '82 or '83 with a stuck motor. Dad always figured it could have a cracked ring but left it alone because it's so smooth. Now it's mine and time for restoration, and I want to rebuild it, and probably put it back to work. Should I do a stock rebuild, or go with oversized pistons & sleeves & maybe shave the head, re-jet or replace the carb, performance intake, or something in between? If there's already a thread on this topic, please direct me to it.

 

[ih560]

The overbore kit is pretty much considered standard for any of the farmall letters series when rebuilding. You can still get a standard bore kit, but it is going to cost you more and you are going to give up the performance gain that you would get from the overbore kit.
I would have the head shaved only enough to have it cleaned up, have new guides installed and probably new seats, because the valves are more than likely sunk into the head. Get new valves too of course.
As far as performance intake and carb, if you want to gain a little, the intake and carb from a super H or newer would do that.

Beyond that , you are looking at mods that are usually only done to pullers and probably aren't worth the returns if you are just going to "put the tractor back to work".

 

[dhermesc]

What are your plans for the tractor AFTER doing the work?

 

[Janicholson]

Good advice. I will ad that higher compression pistons in the kit will be an advantage as well. A 350 camshaft and front gear drives are stronger. The use of a late
H, 300/350 front cover would allow the use of a more common live hydraulic pump at the distributor. Jim

 

[j_w_ander]

My plans for the tractor are the routine stuff it used to do: baling, mowing, plowing/risking, hauling loads to the yard, etc. I just want it to have that little bit extra capability, regardless if I ever call on it. As far as the live hydraulics, I want it to appear stock, so I will skip that. I will have other tractors for that. I might plumb it for dual-acting cylinders, which is basically the same capability. I have a year to think about it, so more thoughts or suggestions are appreciated.

 

[j_w_ander]

Will the 350 cam & gears require a different known timing advance, or should I just play with the variables until I get the best result?

 

[Janicholson]

With increased compression the timing full advance probably needs to be 22 or 24 degrees at high idle. Initial timing (if used with the starter motor, not crank started, should be set so it doesn't fight the starter motor. a guess would be about 4 degrees advance. Modern Ethanol regular 87 R+M fuel will be fine. Jim

 

[ss55]

For your planned use, a newer tractor like a 300, 350, 400, 450, 460 or 560 might be a better match. The cost of the parts and labor to rebuild your H should be enough to trade your H for a newer tractor in good working condition. Until then, enjoy your H as-is.

 

[rhtx55]

You may be able to tell more what route to take once you get it apart. It may just need new rings & the liners honed. The valves & seats may be just fine.
This has NEVER been my experience......BUT.....
it could happen.

There are too many tricks to get a few more ponies out of these and to make one much more versatile to even begin to list here.

I would first line up an IH experienced machine shop to help you determine what needs to be done once you have the engine apart. A good one can save you hundreds, a bad one can cost you thousands.

Good old fashioned experienced help free or hired can help guide you through the process and be excellent at giving you ideas.

They aren't that hard to do.....BUT..there..... are ...ALWAYS pitfalls and unforeseen issues you will definitely need some experienced advice on as you go through the process.

 

[dhermesc]

I tend to agree, IPTO and hydraulics make like so much easier.

 

[j_w_ander]

I have other tractors; this particular H is getting rebuilt because it is a family piece, and because I have the ability to do my own work. I really don't have other people to work on my stuff except for decking/planing, and that's because I don't have the tools. Since my labor is free, parts & path forward are the only advice I'm looking for on this thread, not whether she's worth the effort. They rarely are. My goal is to pass down a running machine that won't require a life or death decision years down the road.

 

[ss55]

You may be rebuilding the H for your own pleasure. The odds that your heirs will put a lot of hours on the H (i.e. another 100 hours total) might be pretty low. They might appreciate the H just as much as-is or with a nice paint job as they would if it had a rebuilt engine.

 

[ss55]

Without tearing the engine down, would a compression test and a leak-down test help to diagnose any problems?

 

[j_w_ander]

It would, but any results would indicate pulling pistons anyway. If I go to that trouble, I might as well put a kit in it. It runs great but smokes a little. Nobody wants to breathe that in all day. I doubt it has any compression differences, maybe just a bad wiper ring. If it's a simple hone & ring job, I might just do that and save her for parades.

 

[David G]

This site has oversized domed overhaul kits, that will light it up nicely. One thing I would do on a rebuild, and does not cost much is put valve seals on head, gets rid of the startup puff.

 

[sflem849]

Ring it and run it.