M carb on a h farmall

I've been told you can put a m farmall
carb on an h farmall,you have to grind
the holes out so it will fit the h
manifold.
Do you gain enough to find and m carb
and clean it and do the modification to
make it fit?
Thanks
 
Without going out and looking at my M and one or both of my H's, my instincts tell me you'd wind up with a cobbled up mess that might not gain anything.

The volumetric efficiency that's designed into the engine is what determines horsepower, fuel consumption, etc., and all the carburetor does is supply whatever quantity of fuel the engine demands. My guess would be that a well tuned H with a well adjusted carb is about as good as it's going to get.

I'll let someone prove me wrong.
 
Goose pretty much explained it. The bigger M carb MIGHT gain a bit of power. But you'd only be able to detect the power increase with a dyno - the increase would not be enough to notice in actual use.

Also the bigger M carb will be badly mismatched at idle and light load. This will result in poor running and possibly increased fuel consumption. Further you'll probably need to modify the governor tube and throttle shaft for it to work.

Your time (and $$$....) will be better spent getting the stock H carburetor into good condition and good tune!
 
The M carb will not bolt up to an H manifold. You would have to do a lot of modification to manifold. The throat of the M & H carbs are not the same size. I don't know if you can do enough adjusting of M carb to make an H run smooth.
 
OR, find a Super H, 300/350 parts tractor, they all used the same size carb as the M with different venturies, jets, etc, and the intake manifolds on the SH/300/350 lets the carb bolt right onto the H.

You guys all make this so hard when IH made it so easy!
 
(quoted from post at 05:20:48 11/09/17) OR, find a Super H, 300/350 parts tractor, they all used the same size carb as the M with different venturies, jets, etc, and the intake manifolds on the SH/300/350 lets the carb bolt right onto the H.

You guys all make this so hard when IH made it so easy!

Exactly!! And for what it's worth, the original H carburetor will supply all the fuel that the C152 engine can use.
 
Unless your needing more power out of the H the easiest and cheapest with out a lot of work is just rebuild the carb thats on the tractor now.
 
Ive seen M carbs on H's quite often at the pulls. On a stock bore it would over fuel the engine and blow black smoke out. But if you put a overbore kit in you would probably be able to tune the carb to make the H run good.
It would be a lot easier and far more effective to just remove the venturi, have it opened up by .080" or .090", re install the venturi, and then incrementally enlarge the metering nozzle holes and main jet hole.
Measure the holes first, then enlarge by no more than .010" at a shot. You'd want pin plug gages to check the size of the holes. You could use drill bits to see what the biggest bit is that fits, it would give you a rough idea of the size but should be adequate. You would want a lot of sizes of drill bits available for this.
You would know that you've enlarged them enough when the engine starts blowing black smoke when the metering screw is all the way out on wide open throttle. Then you can just crank the metering screw back in a little till it just blows a haze.

That would be far better tuning on over bore C152 than slapping a M carb on
 
Yeah, a lot of guys don't realize it, but the H engine at only 152 cu. .in. Is pretty small, so you just tune it up good, Mebbe raise the RPM's a couple hundred, shave the head a little, hone out the intake passages in the manifold smooth as possible, get a PTO or belt dyno and time it and adjust the power screw and that's about all you can get without spending some serious money. IH apparently had fuel economy in mind as well as power when they designed H,s. M's are over half again bigger to pull one more plow bottom. And seem to have a lot more "reserve guts" for pulling.
 

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