Super h and M carb Diffrences?

i know the choke is on the other side, but as far as the insides go are they the same or does the M carb supply alot more gas. Reason i was asking i put the super h carb on my M and it started up but the same prob occured when i put the SH carb on the M. High idle circut cannot be adjusted, and as a result the engine "HUNTS" when you crack the gas open fast. I will go to town and buy a gallon of carb cleener and will let it sit in there for a few days and then i will blow all the ports out again.
2nd question, can i take the bottom part off my M carb and attach it to the top part of my SH carb to see if the prob goes away, or are they diffrent? Thanks to all that are helping.

Save yourself the headache from the smell of cleaners, get some numbered drill bits, clean passages in the bowl. Take a .080 drill bit, run it thru the main jet (remove discharge nozzle first) blow ou the shavings, reassemble, and you will have more fuel out of your Super H carb. Venturi for the SH is a 23, a 25 is in a M. That main jet in your Sh bowl is probably around .050, its hunting, becuase its running off BOTH the idle circuit and the main jet, it takes a bigger sip off the idle, cause the main jet isnt big enough, its swapping circuits back n forth. seen this 500 times or more! I bet if its clean, there is nothing wrong with it other than needing a bigger jet size

Jonnny, I do not know who Drill Bit is, but the tactic he is suggesting is OK for Pulling tractors, it is not OK for users. The original carbs for both SH and M Farmalls were pretty darn good. They work, and have no major issues from the early fifties until now. The passages are plugged up, and the cleaning you are giving it is correct. The use of High Ethanol% fuels will require bigger jets, But up to 15% will run fine with a little opening of the needle you are trying to get working.
If you are pulling, or running E85, do as you think best. Otherwise don't drill anything.
Drilling changes the flow rate of a jet in very uncontrolled ways. Use real jets with different sizes to change things. I am not down on Drill Bit, I just believe it is a harsh and difficult to control method. Jim

Johnnnny: Don't be foolish. You are going to ruin a rare (SH) carb if you start drilling things out. Listen to what Janicholson is telling you.
mike

I will keep you guys posted, i think im on the right track. i was just wondering the main diffrences from the 2. i guess venturi size and jets are not the same. i only run e85 in all my cars and my 44'H and my 40'A when i use e85 i adjust timing and open main jet a bit. but on my 40'A i dint do nothing as it was running a little rich when i bought it.

I just was wondering the diffrences thats all. I am soaking the carb in cleaner and am gonna used compressed air. My super H is my favorite tractor I have. I would never do any thing to it that would change its orignal history. Yes it has a swartz wide front on it but i bought it that way and i have the orignal narrow front. It even has the hour meter on it. I just put the carb on my M to see if it did the sasme thing as it did on my SH, and it did. I have a blockage in the high idle jet and i will work it out with carb fluid and compressed air, if that don't work i will send it off somewhere to be tested. John

No, they are not the same. I don't know if there are differences in the idle circuit, but the main jet on an original M carb is adjusted at WOT by turning in until the engine stumbles, out until smooth. The SM and SH carbs have a "fixed" main jet that produces max power and fuel use with the main adjustment 5 turns out. At that point the needle is not in the jet at all. It can be turned in with less load for better fuel economy.

I agree with Jim on cleaning it out first, but if its clean, and its still acting up, your gonna be looking for "around" that spec of drill bit to make the main jet right, right off the bat. If the M carb bowl is a bigger jet, and it runs good, match em up to each other. To do it right, remove the discharge stem, and the main load adjuster screw, I have set em up in a drill press, but have found a hand held bit driver is perfect to open up the jet. Go small and work your way up, 5 turns out will still play into effect if its done right, but if its clean, lean is mean and its gonna give ya trouble in the long run.

I own 4 almost identical Super H's. All have the 3.5 overbore kit with firecrater pistons. Each were built identically with one exception of the 53 had the head shaved to clean up some pits so it has a bit more compression, maybe 10 psi more over em all, if that. 150 psi for 3 of them, 165 for the one with the head shaved. All 4 have a .080 main jet with stock metering stems, all of em run rich around 4.5-5 turns out, where before, I could remove the adjuster totally and still ran with no load. Hope this helps, but I hope its only dirt,,,,,,

True differences, choke lever location, idle jet diameter, main jet diameter, venturi size, and the rare Super H part number on the tiny ID tag. Other than that, the throttle bodies are the same as a Super H thru SMTA, in the carb bowls, the discharge stems are the same, gasket kits are the same.

Been working on these old Super H's for 20 years, they aint let me down yet in the working clothes.

jonny, I really have NO idea where some of these guys get their information. I've got a '53 Super H with an M carburetor on it, and it runs just fine. I also know of several straight Hs equipped with M carburetors and they also run just fine with NO modifications to the carbs.

Jonnny I'm a little confusued. (nothing new) In your first post on the subject, you said the tractor was hard to start but would run good at wide open throttle all day long. If thats the case the high speed circuit of carb must be okay.
Also you didn't indicate if partially closing choke while running helped or hurt any of your problems. Your carb may be the problem, but don't limit your checking to just it. Have had some that started hard like you said but would run fine that had a ignition problem. Also one with same problem that changing the aftermarket manifold cured the problem. Could have leaked at gasket surface or another problem, I just changed it. If it doesn't help the problem when choke is closed some, I would suspect your getting to much fuel or the ignition system isn't up to parr.