Farmall SMD

Pat Strong · Nov 20, 2010

I have a SMD that the gas valve dropped down and beat the piston up. Does anyone know the largest piston that can be put in them? Can the engine handle having the piston sleeves removed and just strait pistons put in?

tractorsam · Nov 20, 2010

I believe that the largest they'll take is the 4 1/8" overbore that was fitted to the 400/450 diesels. This will make 281 cubic inch displacement. As to running the pistons directly in the block, goodness only knows where you'd find the parts but I imagine it will cause you other issues. Sam

soybeanjoe · Nov 20, 2010

I'm not positive on the SMDs but on the gas engine 4" was sts & 4 1/8" was oversise. As for pulling the sleeve & running a fitted piston, yes it can be done. I have talked to several "old timers" that said that was the "final" overhaul. I know of at least 2 MDs that were ran that way for several years.

caterpillar guy · Nov 21, 2010

Well I don"t know why you would want to run it sleeveless as when it"s done it will be junk.
You could have a sleeve made for that cylinder, if you can"t get one. Or just clean the old piston up with a file and emery cloth and put it back together. If it is just a trailer queen it would run for years. If you are working it every day then you might want to go with the new sleeve.
In my opinion I would not run it without sleeves, unless you just want to junk it when your done. Or pay BIG bucks to have the block bored and inserts for the sleeves to fit into.

John - OH · Nov 21, 2010

4 1/8" same as the 450 diesel

sflem849 · Nov 22, 2010

(quoted from post at 05:59:39 11/21/10) Well I don"t know why you would want to run it sleeveless as when it"s done it will be junk.
You could have a sleeve made for that cylinder, if you can"t get one. Or just clean the old piston up with a file and emery cloth and put it back together. If it is just a trailer queen it would run for years. If you are working it every day then you might want to go with the new sleeve.
In my opinion I would not run it without sleeves, unless you just want to junk it when your done. Or pay BIG bucks to have the block bored and inserts for the sleeves to fit into.

I would like to see him put enough hours on the tractor that it needed a rebuild again! It has been over 58 years and it is just getting opened up so it should be good for at least 25 of light duty work.
If he is pouring the RPMs to it and doing a bunch of stupid stuff he probably should worry about sleeves etc. As for "normal" use and "light duty" tractor pulling I don't think even his kids would have to worry about it.

Farmall SMD

Pat Strong

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tractorsam

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soybeanjoe

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caterpillar guy

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John - OH

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sflem849

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