Maximum horsepower from a 1941 M ???

Happyfeet · Feb 13, 2017

What are my options, staying normally aspirated, to get say 45 plus HP from my M? Can I sleeve it out to say a 450 bore and new pistons? Head work or swap heads? Ignition upgrade? What have you done or heard of that works?

David G · Feb 13, 2017

There are easy gains, and expensive gains, I would just put in firecrater pistons if it does not have them.

pete 23 · Feb 13, 2017

Gasoline head, 4 inch fire crater pistons, battery ignition with 22 degree advance, carburetor main jet for fire crater, governor in like new condition and you will have well over 45 horse power. Wore out governor, look at 40 hp because you drop too much rpm under load.

jasinpa · Feb 13, 2017

dont forget use a gas manifold , not one for kero.

Tom Dowling · Feb 13, 2017

if it's a M block you'd have to bore the block to fit 450 sleeves

PretendFarmer · Feb 14, 2017

4" overbore stepped head piston kit from this site, gas head if it doesn't have it and distributor ignition itself will probably get you around that. Im not sure where you are, but what some people don't consider it altitude. A 50HP M on the coast will not be a 50HP M in Colorado.

BarnyardEngineering · Feb 14, 2017

Yeah, pretty much a standard overhaul using commonly available parts will get you 45HP. No need to go to extreme measures or use exotic parts.

Pretty much all the piston/sleeve kits are 4" overbore with step head pistons. I just checked and all the kits on this site are 4" overbore.

PretendFarmer · Feb 14, 2017

Can you even get standard bore? When I rebuild my C I could not find the stock 3" pistons, 3.125" was all that was available.

PretendFarmer · Feb 14, 2017

Also, you should put a bigger venturi in and enlarge the main jet and metering nozzle. M's came with a #25. You'd be going with a 4" bore which is stock for a SM, so go with a #27 venturi. And per advice given to me, if the main jet size is .050", enlarge it .005"-.010" and go from there.
I don't know what kind of horsepower increase youd see from that but I would bet with the 4" stepped head overbore, gas head and that carb work would put your tractor close to 50hp.

rustyfarmall · Feb 14, 2017

My 1940 M, with 4" flat top pistons produces 46 horsepower on a dyno. Cylinder head is the stock gasoline head. Carburetor still has the original venturi. No other modifications of any kind.

D Slater · Feb 14, 2017

May learn something else today, but don't know of any M that was built with other than a # 27 venturi. 27 was used through 450 tractors so for what poster wants it's good enough.

rustyfarmall · Feb 14, 2017

(quoted from post at 10:07:46 02/14/17) May learn something else today, but don't know of any M that was built with other than a # 27 venturi. 27 was used through 450 tractors so for what poster wants it's good enough.

I've rebuilt quite a few M carburetors. Everyone had the #27 venturi.

D beatty · Feb 14, 2017

Your 1941 M if still original block(248) will not take 450 sleeves with out having block bored. It might be cheaper to find a 264 block that
will take the the 281 sleeves with out boring.

gene bender · Feb 15, 2017

just how much money do you want to spend is the factor. Getting 45hp is more than sleeves and pistons

rustyfarmall · Feb 15, 2017

(quoted from post at 05:40:27 02/15/17) just how much money do you want to spend is the factor. Getting 45hp is more than sleeves and pistons

My 1940 M has 4 inch flat top pistons. No other modifications. It produces 46 horsepower on a PTO dynamometer.

Maximum horsepower from a 1941 M ???

Happyfeet

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David G

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pete 23

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jasinpa

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Tom Dowling

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BarnyardEngineering

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PretendFarmer

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