Farmall M Class Project: Engine woes

Hey guys, I'm posting a little update for everyone who is following this build, so far. We have the tractor pretty well disassembled and now comes the part where we start rebuilding individual systems on the
tractor. The engine is my priority right now as we need to send it off for machining, really just hot tanking the block and head and any other checks they need to perform. I would like to get this done so we
can get the engine reassembled and get it back on the tractor, but we ran into a few large sized snags. As we were pulling the sleeves out of the block, a crack revealed itself to us. We found this on Friday
and it was a letdown to say the least. Also, when we pulled the head off, we noticed a little crack in the head as well. Today, our auto teacher, who is teaching the class with me, magnafluxed the head and
found several more very small cracks in the head, in various locations.
So, what would you guys give me for advice on this? Do I have someone fix the block and look for a replacement head? Or do I try to source a different replacement engine and keep my fingers crossed and
hope for the best? What you you guys do? Thanks in advance!
Andy

IH made 350,000+ Farmall Ms from 1939 through 1952. Surely a good core engine could be sourced from a parts tractor.

I would try, for the used parts supply also, before panicking, IHC had the best valves in the business, but wouldn't hurt to magnaflux them also, it will be a good lesson for the kids to see all the cracks that can be in a valve, under the light!

If the block crack is down the cylinder hole I would just have it bored for a sleeve to fit the sleeve into. I did that on a D-3691 diesel 40 years ago and is still in there with no problems since form that. Both have dry sleeves. The head would depend on where the cracks are and ho many how big/deep. Some cracks don't mean much and other are quite significant to successful working. Might want to see what is around for the head as a possible option in case.

We magnafluxed the head today. I had never seen it done before but the kids enjoyed it. I will certainly do it to the valves as well. Thanks!

All depends where these crack are. Picture. U dont magnaflux valves. U look at the stems if they appear to be stretching they are junk if they have rust pits they are junk. If the margin is thin they are junk. At least this is the first time I heard of magnafluxing valves. Buy anyhow the machine shop knows all this procedure. Unless u are the one doing the head work. Then guided to check. Springs to check pressure.

welp , as for your block sleeve it , it was just stress reliving it's self and a thick wall repair sleever installed then rebored to take a factory 4 inch sleeve and she will out live all of us . Now as to the head ------- Ok so you magged the head BUT did you go and do and OLD FASHIONED pressure check the OLD way not the now way . The old was was to fill the head with water and get it HOT like 220 degrees HOT then add in around 20-30 psi of air pressure and see if it looks like old faithful if not then RUN it , as for maggen the valve like said below if they are not pitted , the stems are round and real close to new stem dia spec.'s and no knife edge AFTER grinding Run the but put new guides in the head . Check the springs for proper seat load . Check the crank for out of round check the block main saddles for roundness and correct if not in other words LINE BORE . Nex up have the cam checked for lift and ware and if your looking for a WEEEEEeeeeee bit more pony power nows the time by having the cam rebuilt and reground . Check the cam shaft key way on the drive gear . As for pistons go with the 4 inch with domed pistons , Be nice if you could get the at least the 5000 ft. pistons , that would wake it up.along with a slight cam rework .

I have seen 350 chev valves, with at least a 1,000 hair line cracks,in them, and it looked perfect,before !!!

and where was these cracks?

From end to end,worse than any New Jersey road map could ever be!

Still not telling me much about these cracks. And what years. When there is a crack it is visual by eye. Never heard of 350s with a valve problem other than worn out guides. Then the valves go to heck.

Well what do you want it's a Chebby .

Sorry to hear that ,Teacher , thats part of tractor restoration sometimes.
I dont know about head repair , here in Ohio ,I would try Harts in Cicel,Ohio or Gardners Competition Performance .
Dont get discouraged , some international engines run 70 years with cracks and weld repairs .
Your students could not have gotten a better project I think to work on. Really

https://goodson.com/collections/crack-detection-repair
Goodson tool sells kits for crack repair and are a source of information also.
Also there is lock and stitch method .

Bates Corp, Bourbon Indiana. They will have anything you need. Ellis

(quoted from post at 11:36:37 09/13/21) Hey guys, I'm posting a little update for everyone who is following this build, so far. We have the tractor pretty well disassembled and now comes the part where we start rebuilding individual systems on the
tractor. The engine is my priority right now as we need to send it off for machining, really just hot tanking the block and head and any other checks they need to perform. I would like to get this done so we
can get the engine reassembled and get it back on the tractor, but we ran into a few large sized snags. As we were pulling the sleeves out of the block, a crack revealed itself to us. We found this on Friday
and it was a letdown to say the least. Also, when we pulled the head off, we noticed a little crack in the head as well. Today, our auto teacher, who is teaching the class with me, magnafluxed the head and
found several more very small cracks in the head, in various locations.
So, what would you guys give me for advice on this? Do I have someone fix the block and look for a replacement head? Or do I try to source a different replacement engine and keep my fingers crossed and
hope for the best? What you you guys do? Thanks in advance!
Andy

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otally depends where the cracks are in the block. If its in the parent bore where the sleeves sit it might be salvageable depending how bad it is. If its easy enough to get to and you have a good machine shop near you they might be able to weld it. Welding cast iron is kinda kinda an art and science. Heads can crack in a multitude of places and repair is likely to be a similar story to the block depending.

As for used parts bear in mind that your possible candidate engines are anything from an M to a 450.