Tecumseh hh100 carb?

I have a older 60s Tecumseh hh100 horizontal shaft cast iron engine on my Massey Ferguson 10 garden tractor I am restoring. I am having difficulty getting the carburetor to function properly. I have cleaned it probably 10 times with everything I can think of but the idle jet still does nothing. The engine will run fine off of the high speed jet but will surge with no load because of the idle jet. I can completely remove the idle fuel mixture screw while it's running and it makes no difference. So for temporary purpose I have adjusted it to run on half choke with the idle stop screw cranked all the way in.

So, is there any particular technique I could try to fix it? I've tried compressed air, carb cleaner and even the terrible wire strategy (and no I didn't break it off in the passage). I would like to buy a new carb but I can't even find a new one online. Does anyone know where I can find one? Finally would a walbro carb for a 10 hp k241 kohler engine work instead? I have four kohler k series engines and never have this much trouble out of those tractors.

What is the general opinion on these old cast iron Tecumseh engines? I am really considering replacing it with a kohler or something else more reliable.

http://www.ebay.com/itm/Genuine-Tecumseh-631304B-Carburetor-Fits-HH100-631304A-631304-OEM-/231812829332

i found this new OEM carb on ebay but its kind of expensive

Thanks. I didn't see that one when I was searching. I have always wondered why the Tecumseh carbs are so much more expensive than the others. I guess with them being out of business parts are getting hard to come by.

IHallis wrote:

I guess with them being out of business parts are getting hard to come by.

i guessed the same thing too... but at this price you might be better trying to buy another used engine...

That's kinda my opinion as well. A little steep for an engine that could need countless other parts soon. Plus it's already near the end of its life before needing rebuilt eventually.

you can search on your local classifieds, i found the engine for my build for 40$ and it had less than an hour on it it just needed a carbcleaning.

Thanks. I'll try that. I normally search Craigslist and check out any local consignment auctions.

I think I can help. Carbs are very sensitive to get working right. Lets start with the basic prep work. Prep work is very important to getting a positive outcome.

Sounds like you cleaned the hell out of the carb and I'm sure it is clean so I won't even go there, lol. But it does sound like you had it on and off the engine about 20 times and that creates unique problems that might be adding to the issue. I'll get to this in a minute.

OK, First thing. Good spark? Pull spark plug and see if it's wet, wet plug means it's not firing right. I had engines where a bad plug would seem like engine is running out of fuel or won't idle so I would turn out idle screw and would run then not run so I turn out idle screw and so on and so on. This might not be the problem but worth a look see. Don't be surprised if it's black with carbon, no big deal just as long as it is not wet with fuel. When engine is running right, the spark plug will self clean.

Next is intake manifold to engine. Gaskets? If you removed intake and put back on, check gasket. maybe there is a vacuum leak here. If gasket is good, check intake to engine mounting surface, should be flat, check with straight edge from bolt hole to bolt hole. If not then sand or file it flat. Check the other end of intake where carb bolts to. Gasket good? Is it flat, if not then file or sand flat. If you had the carb on and off alot then this side, the carb to intake side would be bent from putting it on and taking it off making a small vacuum leak. Next check the carb mounting surface for flatness too for the same reason. I'm thinking you got a small vacuum leak somewhere which would not make the idle circuit work at all. Check the throttle shaft to see if it is worn by moving the throttle side to side, if worn then you need another carb. If the engine doesn't have an intake and carb bolts straight to engine then you just need to check the carb mounting surface for flatness.

Carb setup.... The throttle butterfly should close completely and completely seal the barrel, visually check this with a light behind it and you looking through it. If not, loosen screw on butterfly and retighten till this happens. Next is the idle screw. This screw has a point on the end and when you screw it in all the way into the carb, you should see it in the barrel pocking through the little hole next to the butterfly. This is important because it is confirming you are getting full idle fuel metering.

You should find a problem somewhere along this line. As I mentioned before, I think you are getting a small vacuum leak somewhere which is not directing the vacuum to the idle circuit to work right. Everything should be sealed from engine block to the idle circuit for the engine to idle off the idle circuit. All the symptoms you described suggest this.

Everything else, you should know how to do. Hope it helps.

Thanks for your extensive write up on trouble shooting my carb.

I checked all the gaskets and they are all in great shape. I also checked the butterfly valve and screw and everything is operating properly. The spark is fairly good although I've seen better. I checked that is was actually jumping the gap on the plug. I think I found my two main problems. First the tiny hole in the side of the main jet that feeds the idle jet is partially blocked with rust. I can't remove the jet because it is the non serviceable type which you must replace plus the slot for a screw driver is rounded out (not by me). Nothing I have will clean it while it's together. Plus I found my throttle shaft is worn badly. It really flops around. So I think this carb is pretty much trash at this point. It's amazing you can pull one apart 20 times and still miss a passage. But at least I finally figured it out. Now at least I know where I stand.

Thanks again for all the advice.

Hopefully I can be of help to you, my Massey Ferguson 10 was having carb issues but of a different sort. Mine no matter how the float was adjusted it would spew a nice stream of fuel out the vent hole. Rebuilt it dozens of times. Finally gave up and purchased that exact replacement carburetor, although I found it cheaper. Mine was around $45 if I remember correctly. Here's the drawback though, that carburetor says that it's an OEM direct replacement carburetor designed specifically for the HH100. However there are several issues that need to be addressed in order to make it work. 

First off, the rear mounting boss doesn't protrude out from the carb body as far as the original one did, causing the float bowl to contact the valve box cover (aka the breather). Second off, on the left side of the carb when viewed from the front of the tractor, the body of the carb itself is too thick so that you cannot get a normal 7/16 nut on the carb mounting studs, and still be able to tighten it down to hold the carb tight up against the engine. 

Here's how I remedied these issues: First issue, I took a piece of 1/4" thick x 2" wide x 4" long aluminum flat stock and traced the carb gasket onto it and using a hack saw, file, drill press, and a Dremel, created a 1/4" thick carb spacer. Worked perfectly and if you use a scotch brite pad to shine it up, it looks really good. You will need to install longer carb mounting studs into the block as well. Second issue, I simply acquired an undersided head nut, designed for the same size and thread stud. So since the head of the nut is smaller, I was able to fit it on there and tighten it down. This type nut is often found in aviation but I'm sure you can get one from a good hardware store. 

Issues aside, it is a really great carb. Easily tunable, makes great power, and is easy to work on. Haven't had any issues once I got it installed. As for your current carb, someone in the past probably tightened the idle mixture screw too far down which damaged the seat or the needle itself, causing it to lack any significant adjustment. You might be able to acquire a replacement needle off of the Internet somewhere if you choose to fix your current carb. 

Also while I'm here I may as well re-assure you of the Tecumseh engines. When I first got mine, it burned more oil than gas, and eventually, on a full throttle run, blew up while hauling butt in 4th gear. Rod snapped in half, piston shattered, camshaft stayed intact, crankshaft had minor repairable burn marks on it, and the rod knocked a nice chunk off the bottom edge of the cylinder. Rebuilt it once, and abused that engine to the point where I thought it would break on me, but it didn't. It kept up with the abuse and never skipped a beat. Just today I finished rebuilding it for the second time after I clocked more than 2000 MAJORLY abusive hours on it. Only thing that was hurting was the rings, partially due to improper break in procedures the first time. This second time however it has turned out much stronger than before and doesn't burn a single bit of oil. It really is a great motor. It just wants a little bit of money thrown at it in order to be happy. As for rebuilding, rebuild kits can be had for a little over $100 and you don't even have to pull the block out of the tractor. 

I also have 3 Kohler K-series. One 10hp and two 16's. Great motors too, but they are HUGE. I've seen pictures of the smaller K-series (10 & 12 hp) swapped into Massey's and they were absolutely chopped to death. Totally not worth it. 

Sorry for my giant speech, but good luck and feel free to ask more questions you may have. 
-Mason

Thanks for all your advice. I had read online somewhere about needing to make a spacer for the carb but didn't remember exactly how much. I also didn't realize that the nuts were too close to the carb body to turn. However it makes sense because all my other Tecumseh motors are just like that with two bolts through the manifold and you turn the entire bolt.

Here's my question. I am not certain if my old studs will even come out because they are severely rusted plus I am not sure if I can find new ones with matching nuts at my local store (tractor supply). However i could easily fabricate a short intake manifold which could bolt on to the original studs and have a flange on the other side for two bolts to hold the carb. This would act as a spacer and solve my clearance issue. I could make it very short so as not to interfere with anything like the governor linkages and tractor grill as well.

My other option is if I can remove the studs is to use two hex head cap screws instead of longer studs and undersized nuts. I am not sure if this would work though. Can you thread those into a hole designed for a stud or would it destroy the threads over time? I know my kohler are setup that way.

Yeah I know those kohler engines are beasts. I have 4 of them in other garden tractors I've restored. One 7 hp, one 14 hp ,and two 10 hp. It's not worth the money, time or destroying the tractor to make one fit.

May I ask what you use your Massey for? I am assuming either as a workhorse or an off-roader. Definitely not a racer with their weight.
Did you pulley swap it and if so how did you get around the torque converter? I am just trying to restore mine to use around the property and have fun cruising around on on the paths. I may show it some but I'm not strict like other people with restoring them. I build them to have a good time with. Not to sit around and look good and make sure it doesn't get scratched.

Thanks again for sharing your knowledge.

To get the studs out, soak them a day or two before you go to remove them with a good penetrating oil like PB blaster or Kroil. Depending on how rusted they are maybe even longer. Then find two nuts with the same thread pitch as the stud and thread them on. Once they're on lock them nice and tight up against each other and turn them ccw both at the same time to pull the stud out. Don't force it too much or it could break off, and just take your time. If it won't budge at all, soak it for a few more days and then continue. 

Once you get the studs out, you'll notice that the threaded part of the stud that was inside the block has a courser thread pitch than the outside part. As long as the hardware that you get has the same thread pitch, it won't tear the threads up at all. The cap screw idea I didn't even think of when I did mine. It should work just fine as long as the head of the bolt is small enough to clear and also get a wrench on it to tighten it down. 

As for mine, my Massey is my main off-roader and occasional workhorse. I have 26" Executioners, 18" Rhox Rxal's, and a 2500lb atv winch on it along with a bunch of other stuff. I've gone through and rebuilt everything on it over the past 2 years. I built it mainly for mud but it's great at everything. Only work that it sees is moving trailers, towing broken equipment, and hauling firewood. It is indeed one heavy tractor, but it is faster than you would think. I have not pulley swapped it, due to the varidrive system. However I have found a few hacks to get more speed out of them. First trick is to spend the $100 or so and buy both brand new drive belts. It made a huge difference on mine. Second one was to swap out the rear belt's weak tensioner spring for a stronger one. Last trick is to place all of the shims for the rear split drive sheave inside of the sheave so that it makes the pulley *smaller* in a sense. The stiffer spring compensates for the extra belt slack. This netted me a total of 18 mph on flat ground with tires aired up at 8 psi. As a side note though, I run my engine at 4000 rpm since I put stronger internals in it. 

Glad I could be of help;
-Mason

Sorry I haven't posted an update on this problem. I did find a solution though. I ended up pulling a carb off of a Tecumseh hm100 engine parts engine I had. This carb is almost identical to the aftermarket one for the hh100. The main obstacle I faced was the throttle shaft tab for the governor linkage was on the opposite side of the shaft. I solved this problem by welding on a new tab on the other facing the correct direction. I also used cap screws to mount the carb which work excellent. Overall the engine runs great and it didn't cost me a cent.