190XT Carb Replacement/Rebuild

I'd definitely be rebuilding the original and not replacing it if I were you. It's very, very (very) rare for a new/aftermarket carb to be as good as a properly rebuilt original. Usually, new/aftermarket ones much worse quality with lousy porting/machining. The only way to get a decent aftermarket carb is if you spend $500+. But even then, it's only going to be as good as a rebuilt original would be, but cost you 10X more. Rebuilding carbs is pretty easy/standard practice, and those carbs are dead simple to tear down and rebuild. In the last 5 years or so there seems to be a lot of folks trying to buy replacement carbs rather than just taking half an hour to rebuild the original, and a lot of problems resulting from it: The annals of all antique machinery forums are filled with stories & posts of folks who bought lousy aftermarket carbs, chucked the good OEM ones, and then have trouble getting them to run correctly. For tiny/simple carbs on small engines, aftermarket carbs are often great and function fine. But for any larger carb, you're far better to just spend a little time (and a fraction of the cost) rebuilding the original

As Doc mentions, 'The Carburetor Doctor' is a great source for parts & info on all carbs. Their rebuild kit for that carb is #CK0619 - cost about $50. You can usually find kits cheaper, but it's nice to support 'the carb doctor' because it's a great site/resource and you know you're getting the right kit. If you order one off Amazon or elsewhere for cheaper, it often takes a little more cross-referencing and checking to make sure you're getting it right. When I did a carb for a 180 not long ago for example, Amazon listed two carb kits compatible with the Zenith I had. Both listed the Zenith # I had and both said they worked for the standard carbs on the 180 and 190, which definitely wasn't true as they were different kits, and the 180 and 190 used different sizes of Zeniths 62's. Took me a little more cross-referencing to find out which one I wanted. Better to just spend the few extra $ and get the one that is definitely correct from the carb doctor. See link below:

That is what I am thinking too. It looks like someone was in there before, and based on the fact that they used some kind of epoxy or other hard sealant... Not too sure I'd be confident in whatever else they did inside the carb.

It's not proper to judge based off a picture, but even though there are signs of some farmerization/cobblefication, I would certainly think it's usable/rebuildable without much concern. As Steve notes: It's currently running and looks complete, so it can't be too bad. A few other things to consider when you're working on it:

i) Hard to tell from the picture, but it looks like something might be awry with the carb-manifold interface. On the left side you can see the gasket, and also see the attachment bolt poking through a few threads like it should be. But on the right side it looks like there's a gap where the gasket should be, and the bolt threads don't protrude through at all. I wouldn't be surprised if you find something's up with that interface and it's currently sucking air. Make sure those surfaces are clean and flat with a new gasket and bolts torqued evenly.

ii) The section of rad hose used between intake pipe and carb is a little wacky. Not only because the PO has it clamped off the carb body for some reason. But on those higher-displacement gassers, it's not uncommon for them to flood and put a bunch of fuel into the intake tube if it's cranked excessively with the choke on. You want to make sure that hose is fuel-compatible and not going to disintegrate if in contact with fuel. I used a silicone hose from Amazon for my 180.

Just fyi: There have been a few cases talked about on here in the past year or so of the mechanical fuel pumps on these old gassers going bad (cracked diaphragm) and dumping a pile of gas into the crankcase. Rebuild kits for the mechanical fuel pump Allis used on the G2500's are available from 'Then and Now Automotive' in Weymouth, MA. Their part number for the kit is CK-4220. I'm not suggesting you need to rebuild it preemptively. Just keep an eye on it for any signs of fuel flow problems or dumping gas into the crankcase.

Good luck with it. I'd love to find a gasser 190. A chap up the road has one and I'm quite envious. I have the gasser 180 (same engine) and it's one of my favourite tractors. A little thirsty when on the plow or round baler, but it purrs like a kitten down to 200-300 RPM, starts instantly in all weather, and is superbly smooth.