There's got to be a trick to these M-style carburetors!

[hippy5488]

this is not his problem as he said he can push float without bowl on and stop fuel flow. but i ran into another problem on 2 different kits last week. the needle didnt stick out of the seat housing enough so the float hit the seat housing before it would of shut off fuel. ihs4037 kit and ihs3616 kits with 2 new ihs 387 floats. had to mill .040 off of seat housing. caught when assy. so wasnt that big of a deal but the qaulity of parts we get thes days u have to double check everything.

[Matt Kirsch]

It's together on the tractor and it ran the last time I tried it. If I have to pull it apart again I'll take a picture for you, but I expect that I won't try to start it again until the day of the open house, at which point it is what it is.

That's assuming I'm not stuck doing jury duty that day. Just got a notice in the mail that I'm on call for the week of May 12th. %$#@!!! I was supposed to start driving school that week too, and had to postpone.

[Matt Kirsch]

As Robert Stack was fond of saying: UPDATE!

Apparently I got it licked. On Tuesday at the open house, one of the potential bidders wanted to hear it run. I admitted it could be a crap shoot because this carb was fond of flooding, and that I had just put a kit in it, which was met with several understanding nods and words of agreement on how sensitive the floats were on these.

Long story short, it started. Even needed a blip of choke. No drips.  

They kept me hopping all day at the loadout, but I did catch sight of it driving out on its own power. The same guy bought my Stage II Super M too, apparently as they were both headed out on the same load.

Not my problem anymore. 

[drglinski]

Following up on this post as I am experiencing similar issues with my M carb as of late: 

 

-acquired tractor in summer of 24.  Had no fuel leaks. Tractor ran horribly and struggled all winter.  

-spring of 25 I bought a full carb rebuild kit from Dwayne Hansford.  New parts/needle and seat etc.   Reset float to IH manual specs.  Didn't find an issue with the float not floating (tested it).  Tractor starts up and runs excellent, but pi$$es gas out the overflow.  I even swapped back to the old needle and seat but that didn't do squat. Since then I simply shut the fuel off at the sediment bowl and it's been fine

 

Until today.  Even with the fuel shut off it piddles out the center of the carb.  I'm not sure what to look for.  I read something about a gasket being put on backwards and a blocking a vent? But I can't find any photos of that so I don't know what that is.

 

Any thoughts? 

 

Thanks 

[Matt Kirsch]

Your sediment bowl is bad if it doesn't stop running with the fuel valve shut off.

Did I pull the fuel bowl with the carburetor still on the tractor? Can't remember, too lazy to backtrack through the thread. Just spent the last two hours outside shuffling trailers around and I'm trying to cool off.

That's what I'd recommend doing at this point. Take the bowl off and see if you can manually stop the fuel flow by pushing up on the float. Then it's a matter of keeping the float from hanging up on the inside of the fuel bowl. You pretty much need x-ray vision to do that.

[Hudco]

have you set the bowl leval in the vise and carfully filled the bowl with gas to see if their are any cracks in the bowl from having some water and freezeing  that can happen can also see if the nozzle gasket leaks that way    have to really pour the gas in carfull because it will wick up a mile  but it only needs to be deep enought to be above the nozzle gasket

[HydroTek]

Just need to hold the carb in your hand with the float pivot down
-- then tip the carb back and forth about an inch
-- listen for the float to swing over center -- the little tick tick sound 

Common for the float to bind on the housing, or to be dented and not hold enough air to actually float 
-- both can be fixed with patience and experience 

[Jeff-C-IL]

Send it to Big Steve here on the forum.....I took a carb off a 656 to him last year, it came back perfect.   Tractor starts and runs like a top.   He does work out of a home shop....not sure if he has a specific business.   You could try a PM.

[Matt Kirsch]

15 hours ago, HydroTek said:

Just need to hold the carb in your hand with the float pivot down
-- then tip the carb back and forth about an inch
-- listen for the float to swing over center -- the little tick tick sound 

Common for the float to bind on the housing, or to be dented and not hold enough air to actually float 
-- both can be fixed with patience and experience 

I've had floats do the tick-tick deal and still hang up once installed on the tractor.

Then if it doesn't tick-tick, how do you determine where it's hanging up? I've heard look for signs of contact, shiny spots, etc., but there has never been any such evidence in my experience. It's hung up on the bowl, not rubbing on it. You need movement to make a shiny spot.

[HydroTek]

1 hour ago, Matt Kirsch said:

I've had floats do the tick-tick deal and still hang up once installed on the tractor.

Then if it doesn't tick-tick, how do you determine where it's hanging up? I've heard look for signs of contact, shiny spots, etc., but there has never been any such evidence in my experience. It's hung up on the bowl, not rubbing on it. You need movement to make a shiny spot.

Look straight down on the float with the carb top in your hand.  You can get a view of the area the float will be working in . Check that the float pivot does not have excessive slack in it , allowing the float to move sideways . Check that the floats sit level to the carb body, see where one is higher and will cause the float to swing to one side 

Be sure the float is not dropping too far , this can cause the needle valve to bind sideways and leak 

Suspend the float in a can of gas, using a wire thru the pivot hole

Does the float actually "float" ? 
-- hold the pivot end at the level of the gas in the can 

Seen floats with too much solder on the seams
or dents that limit the air capacity 
-- need to look for this kind of stuff 

-- or swollen floats from over heating
sides should be relatively flat 

Almost all of the new floats I have installed need to be tweaked a little to work in the carb 

[Matt Kirsch]

1 hour ago, HydroTek said:

Look straight down on the float with the carb top in your hand.  You can get a view of the area the float will be working in . Check that the float pivot does not have excessive slack in it , allowing the float to move sideways . Check that the floats sit level to the carb body, see where one is higher and will cause the float to swing to one side 

Be sure the float is not dropping too far , this can cause the needle valve to bind sideways and leak 

Suspend the float in a can of gas, using a wire thru the pivot hole

Does the float actually "float" ? 
-- hold the pivot end at the level of the gas in the can 

Seen floats with too much solder on the seams
or dents that limit the air capacity 
-- need to look for this kind of stuff 

-- or swollen floats from over heating
sides should be relatively flat 

Almost all of the new floats I have installed need to be tweaked a little to work in the carb 

*SHRUG*

I did all that. Looked fine to me, and I have a very good eye for straight and square. Float floated like a boat on the ocean.

Only thing that worked was randomly tweaking things until it stopped leaking when I put it back together.

[HydroTek]

Leave the bottom off the carb , and lift the float with your finger
-- does the fuel shut off ? 

Had one years back that the threads for the valve were tapped crooked
-- the valve would sit cocked on the gasket 
weird thing had been like that from the factory

Does not take much to hang the float
-- have seen the rough cast in the bowl hang a few over the years
-- die grinder will fix that , just polish the nubs off 
-- float dropping to far as I mentioned earlier is also a problem -- usually a whack on the carb temp fixes this 

[TroyDairy]

Can anyone direct me to a carb guru whom is making 3D printed EFI conversions for these old gassers?  Our 464 is same deal, lost track how many time fiddle with carb then leaks, seen 5 guys whom are all well respected and it runs for 10hr then no start and leaks, gutless vs before restoration and we have nearly tore engine back down to core and finding 0 issues.  i believe a fella in the Carolinas was making 'dumb' efi for these.  They are huge improvements i have read somewhere. Easton maybe knows, Ernie perhaps name?