Farmall M head replacement

Can a head from a Farmall 400 tractor be instated on an M Farmall without any modifications? I have access to a 400 parts tractor and need an M head.

Thanks in advance.

Dave
 
Yep, there may be a slight difference in the breather tube that screws in the back of the head. The M has one the 400 does not. It can simply be plugged. The only other thing is if you had a distillate head on your M and aftermarket high dome pistons were installed to raise the compression they will hit the valves and chamber roof in the 400 head. This is a very unlikely scenario.
 
Per the CNHI parts book the push rods, rocker arms and the stands for the rocker arm shaft have the same numbers or are said to be interchangeable..can be used for.. between the two engines. And I am certain the head height from the head gasket to the valve cover gasket surface is the same, that is where the rocker arm assembly bolts to. The valve lengths may be different but that only adjusts for differences of the combustion chamber pocket or the depth they are installed from the head gasket surface. Which is adjusting for differences in combustion chamber volume. Still staying with my answer that they are interchangeable.
 
i do know from a few years ago the stems are longer. than the w6 and m heads. when i redid my 400 head. and i am not looking in any books either.
 
Three pictures on the questions. Top of 400 gas head, use short pipe in head at threaded hole at front of head. M pipe over rockers not used. Get valve cover with head, fitting in top has a metering orifice. Use a hose over to air cleaner like later ones. M pipe you remove can be used for ends. Unless you have a piston like picture, probably won't have trouble with clearing. Longer valves because combustion chamber not as deep. 400 head including 400 valves no problem.
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This post was edited by D Slater on 09/17/2022 at 06:22 pm.
 

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