Deere '41 BN Questions

Been reading the forums for a few years.. but never needed to ask any questions until now.

Took in a '41 BN on trade for a few dumpsters I did for a client. Took it because my father was born in '41 and has talked about owning a JD even though he lives in the suburbs of Chicago. So I figured why not one for the year he was born... nice B-day gift... and to drive the grand kids around the neighborhood and possibly some local parades. He wanted to scrap it last year because it sat untouched, but now has changed his tune since I tore it down and took the head and cylinder in to be worked.

Anyway, just getting around to rebuilding it. Took the head in and found I only needed new intake valves, everything else was fine. Just replacing them and a nice shave to level if needed.

Now comes the cylinder. After reading other posts, I found out the max bore is 4.75". So with that stated, if bored out to 4 11/16, I can use late B standard pistons without any modifications? I know I have .045 option... but can't find .090's anywhere... even Sharp's. Just covering just in case the head doesn't need to go to 4 11/16

They haven't started the work yet, just making sure before they start to machine it. This is the first tractor they've done, but have many years with both cars and diesel trucks under their belt. Their equipment can handle the bore size.

This is our first tractor... all I know about B's is from reading forums and literature about them. Thanks in advance for your time and input.

The cylinders need to be checked for wear before you need to find pistons. You might not need new pistons. This site has .045 piston sets.

I understand that... but the question in short is can late model B standard 4 11/16 pistons work? My in-laws have a brand new set they never usd and they are offered if needed.

They're machining the cylinder Thursday and will let me know how they clean up. They're planning on going .040 over to see if they're clean. If so, then I'll get the .045's and they continue from there. But.. there's a chance they might need to go bigger, thus the 4 11/16 question.

Update: Heard back from the shop and said I could get away with using .045's. But later in the conversation he said they may be a chance that at .045 there might be some slight pitting left over and thought that wouldn't be a big deal. I asked him if 4 11/16 would be enough to get the cylinder totally clear and said yes.

SO... again.. the question... Can I use the later 4 11/16 pistons in the '41 without any modifications? Will it still have the same clearance?

A little pitting won't hurt with all those rings in there. That bottom skirt gets pretty thin when you go to 4&11/16's.

Yes you can. That is only 4.69", you can go 4.75".

Thanks for the responses. So with the minimal pitting there is, should I go with the 45's? Or... if I can find a set of 90's, should I go with them instead of the 4 11/16's?

I suppose to some extent we all ask ourselves what is the intended result and was is the intended use of the tractor. I've invested in some repairs for my 430 based on my own cost/benefit tradeoff analysis. For this tractor, having "better than factor perfect" is a heck of a lot less important than "reliably starts and runs and plows the driveway a dozen times a year". And the cost of the later is easier to justify than the cost of the prior.

If your tractor is of the "pulls the float, makes great noise and generates smiles" end of the equation then a pit or two may suffice vs extra investment in larger pistons and more boring.

I suspect that in the end, each person's goals and pocket book will determine their level of happiness with the results .

They had to bore it a little to clean it up... so using the old pistons are now out of the question. It's sitting at .040 right now until I get the set. Once they get them in the shop, they're going to measure, then continue to bore until there's a perfect fit.

I would consider the tractor 'retired' from actual work. It will be used in local parades... along with putting around the neighborhood. I wont say money isn't the issue, but if I have to spend a little more to make things run right for the next 30-40 years, then that's what I'd like to do. Eventually, I'll take ownership and will probably be passed to my kids or grandkids when it's time. I just don't want to have to tare it down in 5-10 years... or have it smoke.