M carb.

robertw · Sep 3, 2014

I have a farmall m that i pull and it has 150lbs. of compresson and i was wondering what size in thousands the hole is in the high speed jet is and how much bigger it could be can't get know black smoke with the screw turn out a long ways maybe 7 turns with rpms high or under load and was thinking it may have the stock jet in it and iv'e read on this web site that you could drill it out some but don't know how much and would the stem that feeds the engine need to be bigger can't think what they call it starts with a v i think
Thanks for any help ps just need a little more power
Thanks again Robertw

Janicholson · Sep 3, 2014

Wirh number drills (not fractional!!) put bits in the main jet hole until you find its real size (just fits) Then use the next sixe larger for the first "enlargement". It takes very little increase to change the mix radically. The Venturi can be changed out to a larger size. from a 450 carb I think. Jim

kub6040 · Sep 3, 2014

You could just use a 450 carberator, and save guesswork .

D Slater · Sep 4, 2014

Can't say what your carburetor needs setting at the computer. May give you some idea to know that when IH sold some higher compression overbore kits. Jet size behind the adjusting screw was originally around a .057 hole size. With fire crater 4 inch bore pistons the hole size was changed to .061. But other parts in the carburetor were changed also.
Original SM, 400 and 450 carburetors used the same venturi size as the M. Also the same size throttle plate and carburetor throat.

robertw · Sep 4, 2014

Thanks guys you've been very helpfull
Robertw

M carb.

robertw

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Janicholson

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kub6040

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D Slater

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robertw

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