m carbs

I know that super h - 450 will bolt on to the m motor but is there any difference in the inside of the carbs ?
Thanks Robertw

Not positive,but I think the venturi and jets are different.

the m series , w6 series are basically the same carb. difference is in the jetting. also the 450 carb has the choke rod on opposite side from the 6 series. I thought that the h and w4 had a smaller bore.

H/300/350 all have smaller bores and the mounting holes will not line up with the manifold on the M/400/450. The smaller carbs can be adapted to work, but you will not be supplying the air/fuel mixture that is properly required. Now a lot of pullers put a M/400/450 carb on the H/300/350 via and adapter to supply more fuel for larger cubic inch engines.

(quoted from post at 08:48:14 06/29/15) H/300/350 all have smaller bores and the mounting holes will not line up with the manifold on the M/400/450. The smaller carbs can be adapted to work, but you will not be supplying the air/fuel mixture that is properly required. Now a lot of pullers put a M/400/450 carb on the H/300/350 via and adapter to supply more fuel for larger cubic inch engines.

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Farmall H is a smaller bore, and in fact the carburetor is basically 1/2 of the M carburetor. The SUPER H uses the bigger carburetor, basically the same as an M through 450. The venturi and main metering stem will be specific to each tractor model, but those parts WILL interchange. The W9, 600, and 650 use the same basic carburetor, but with a much larger throttle bore.

A carburetor from an M WILL bolt up to the manifold of a Super H, but will NOT bolt up the manifold of a straight H. If you want to put an M carb on an H, you need a manifold for a Super H, 300, or 350.

That is what I was wondering if the jet and venturi or anything else different as I pull this tractor it has 150 lbs. of compression and I can't seem to get any black smoke out it when under a load and wondering if going to a super m to 450 carb would help for any more power.Thanks again Robertw

(quoted from post at 09:50:01 06/29/15) That is what I was wondering if the jet and venturi or anything else different as I pull this tractor it has 150 lbs. of compression and I can't seem to get any black smoke out it when under a load and wondering if going to a super m to 450 carb would help for any more power.Thanks again Robertw

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First, make sure the high idle metering screw is turned the full 5 turns out. If that is already done, then pull out the main metering stem. At the bottom of that stem are 3 small holes. Actually 6 because they go all the way through. Enlarge that bottom hole by just ONE drill size. Number and letter drills, not fractional.

Thanks Rustyfarmall for that advice I will try that

The M is a no 35 from the factory the super and 400 is a 33 and the 450 is a number 32

Thanks fastfarmall for that advice vary helpful is that in the bottom of the carb.

Robertw

For the most part M, SM, SH and some of the 100 series distillate carburetors use the same throttle body. Bowl castings are the same size but can have the choke lever on different sides and some or all of the metering parts can be different. When the 100 series = 300-350, 400-450 carburetors with idle mixture adjusting screw located just below the manifold flange came out changes were made to the castings. Bowl used a screw in discharge nozzle without a retaining nut of previous carburetors. Throttle body didn't use the off idle air passage. Plus other metering changes. M, SM, 400 and 450 all used a # 27 veturi. All those carburetors can be made to perform.
Don't know what size engine or changes you have. Example of changes IH made to M carburetors when making them a 264 cubic inch with fire crater pistons follows. Some orifice sizes can be off .002 when checked.
50983DC M carburetor, main seat size .054 or .055. with fire crater .061. Main discharge nozzle top hole .042, middle .046, bottom .053. Tip .111 to .113. Fire C. top .069, middle .043, bottom .063, tip .136. Idle jet change from .025 to .022. Air bleed size the same in a 50983DC. If I remember correct some or all with suffix below DC got a air bleed change. would have to check my memory on that.
Same amount or near the same amount of air or will flow through all those castings if the same size venturi is used. Fuel metering is adjusted for engine size and applications.
Some 9 series carburetors had a bigger throat and butterfly than the above carburetors but the same manifold bolt pattern as a M.

(quoted from post at 13:28:07 06/29/15) The M is a no 35 from the factory the super and 400 is a 33 and the 450 is a number 32

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No, the M is a #27 from the factory.