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So, I just started using my Tecumseh H70 *I think its year is around the 70s - 80s, I honestly have no idea or knowledge on this engine that's just my guess. But I've been rototilling with it and it has been dying when it would touch the ground and didn't even rototill, I've adjusted the mixture screw a lot and I have it one turn out and a small touch past that after the one turn out, but then when I put it high throttle it will sputter and die when it touches the ground and black smoke comes out of the muffler, there's also white smoke coming out of the oil drainer tube at the bottom of the engine (I think it's smoke at least), I have w40 motorcycle oil in it and I just replaced the carb with a cheap one. I honestly have no idea what's wrong with it at this point, I know that the conditions are crappy for rototilling and I will probably get flak for rototilling in the mud... But that stuff is clay and I'm not sure if it will dig that clay up when its rock hard (Ps: that's not a garden, it's for planting boxes so grass won't grow up). Anyway, it will only rototill and dig deep on a certain spot on the throttle otherwise it sputters and dies. So yeah if anyone has any thoughts or suggestions I would be happy to hear them! Here's a video of what it's doing (Ps: the GoPro is in my mouth so there's breathing) This video doesn't show it rototilling and dying that's when the black smoke comes out, it's really weird, this kind of does it as I'm looking back at the video I have posted, when it's rototilling it will start to power out and sputter and that's when the black smoke comes out, and then it runs rough until I throttle it down again and then sometimes it stays running or it will quit.

Black smoke from the exhaust is rich running.
Usually because the float valve is not cutting the fuel off or the main jet has fallen out.Engine will run fine when not under load but when the throttle opens it gulps way too much fuel , floods & dies.

Not so common reason is a fouled plug so do the easy bit first & change the spark plug.
Even less common is a bad coil.

Search Tecumseh carb rebuild in the forums and you will find the proceedures & the correct kit for your carb.
I see 5/8 of SFA Tecumsehs down here but other techs on this forum have the proceedures down pat.

Here is the cleaning and rebuilding procedure I’ve used for years and at this time of year I’ll rebuild around ten carbs a week. I’m assuming the rebuild kit you will need is 631021B, but if you will post the numbers off the shroud, by the plug, I’ll double check and let you know. Also included the adjustment procedure after rebuilding plus service manual. https://www.mymowerparts.com/pdf/Te...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf

[FONT=&quot][FONT=&quot]Needle and seat replacement.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]Remove the carb, and then remove the float bowl. Check the float bowl jet (which is the bowl screw) and make sure the jets both horizontal and vertical are clean and open. Tip the carb upside down and remove the float pin and float with needle attached. Look in the float needle passage and you should see the red float seat at the bottom of the passage. This is where a #5 crotchet hook would come in handy as you need to remove this seat. If you have no hook, but compressed air, you can blow through the fuel inlet and try to pop the seat out. Put your thumb over the passage to prevent the seat from flying who knows where. No air or hook try bending a stiff paper clip to dig the seat out.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]I would either give the carb a good 24 hour soaking or have it ultrasonically cleaned at this time.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]With the seat out clean the passage way with carb cleaner. Now you must find a drill bit slightly smaller than the passage way, to be used to press in the new seat. Apply a very, very small amount of a very light lube to the new seat. 3-1 oil or lighter, to help seat it better. Carefully insert the new seat in the passage way with the rings on the seat down toward the carb body. Slowly and carefully force the seat down with the back end of the drill bit. Once it is seated, check to see that it did not flip and the rings are up. Next check to make sure that the float does not have any liquid in it. If it does, replace. If everything looks correct, attach the new needle to the float and install with the float pin centered. It everything is correct, the float should seat level to the carb body, when looking at it upside down. If everything looks good reattach the float bowl, making sure that both the bowl gasket and the nut gasket seal properly. Reinstall on the engine and test unit. Remember to have patience and take your time. Good luck, but I don't think you'll need it.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]PS: On the side of some Tecumseh carbs you will find a plastic cover. Under this cover will be an idle jet. Remove it and check to see that the jet is open both horizontally and vertically. You should be able to push the old float needle wire through the vertical opening.

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[FONT=&quot][FONT=&quot]Adjusting a carb[/FONT][/FONT]
[FONT=&quot][FONT=&quot]Ok, the first thing I would suggest is to reset the armature air gap with the single thickness of a business card, unless you are sure you have a gap of .010 inches. I don't normally recommend doing it this way, but in your case it may be best. Second, this is the procedure I always taught my students to adjust a carb with two fuel controlling needles.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]1. Start the engine and move the throttle control to top speed.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]2. Adjust the high speed needle (this is the one under the float bowl) clockwise very slowly until the engine starts [/FONT][/FONT]
[FONT=&quot][FONT=&quot] to bog down.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]3. Back the needle out 1/8 turn, the engine should now run smoothly.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]4. Now move the throttle control down to idle. If the engine stalls out turn the idle speed screw in one full turn,[/FONT][/FONT]
[FONT=&quot][FONT=&quot] restart the engine and bring the throttle control down to idle. If the engine is running to fast, turn the speed [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw slowly out until the engine seem to want to die and then in 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]5. Now with the engine running, adjust the idle needle out until the either gains in RPM's or starts to bog down. If[/FONT][/FONT]
[FONT=&quot][FONT=&quot] the engine gains in RPM's, continue to adjust out until the engine starts to bog down. At this time turn the [/FONT][/FONT]
[FONT=&quot][FONT=&quot] screw in 1/4 turn. Now the engine may be running to fast, so turn the idle speed screw out until you get an [/FONT][/FONT]
[FONT=&quot][FONT=&quot] RPM you like.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]6. Now you must repeat step 5. If the engine bogs down right away turn idle needle back in to your starting point [/FONT][/FONT]
[FONT=&quot][FONT=&quot] and go to step 7. If it speeds up, repeat step 5 again.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]7. Turn idle needle in until the engine bogs down and then out 1/8 turn.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]8. Now the engine should run smoothly at all speeds.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]9. To check, set the engine to idle, then quickly push the throttle control tohigh speed. If it dogs and does not [/FONT][/FONT]
[FONT=&quot][FONT=&quot] come to speed, open the idle needle 1/8 turn and repeat.[/FONT][/FONT]
[FONT=&quot][FONT=&quot]10. Set to go.[/FONT][/FONT]
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[FONT=&quot][FONT=&quot]There are 2 reasons I have it done this way is, first the high speed needle controls the fuel going to the low speed circuit and second is that the idle needle controls how much fuel is used when going from idle to high speed. You should also review the section in the manual I posted before starting this procedure.[/FONT][/FONT]
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But here it runs fine: https://youtu.be/caPblQyuEQU, It also has a brand new carb, I cleaned the main jet and the one by the threads that's hard to see, it's a cheap 16$ one I got off ebay new, so it shouldn't need another clean, I added a gravity fed gas filter because I saw dirt in the fuel line, I also added a gas shut off. I'll try what you said about adjusting the carb and see if it works

Clean and adjust your points.

So I tried that I may have done it wrong, but now it won't even start

Did you get the flywheel back on right with the key in the slots. Check for spark at the plug.

The condition you described earlier indicates a fuel, not an ignition problem. Hopefully when you adjusted the points you did not move the coil assembly. If you did, you changed the timing and will have to readjust it. On the old Tecumseh engines this is not easy, there is a procedure in the manual I posted earlier. Make sure you torque the flywheelnut properly or you will shear the key the first time it fires.

Dirty points will cause it to run poorly and mimic a rich running condition.

Inability to adjust out the carb is another indication. Your problem is most likely ignition related...

Tecumseh used at least three, maybe more, different carbs on the H70 models. If you didn’t purchase your new carb using the correct spec number, you may have gotten the wrong carb for your engine. Can you give us the spec number off your engine and all numbers and info you have on the new carb you purchased. We might be able to see if you have the correct carb for your engine or which carb you need.

I didn't adjust the points stuff, I meant the carb sorry, the one at the bottom of the float bowl and if that doesn't work then I'll focus on points. However, I can't get it to start after I adjusted the float bowl jet (I think that's the main jet) and I can't find the sweet spot I had it at, that is what I mean by it won't start now.

https://www.ebay.ca/itm/262759321160?ViewItem=&item=262759321160 Thats the carb I bought, I'll get the numbers on the engine tonight

Go back to the vendors ebay page and click on "See other items"
Then have a look at what turns up.
If all of his stuff is mower/engine related then there is a good chance he knows what he is selling and it has come from a reputable supplier as servicable items.
OTOH if he is selling everything from condomes to X-ray curtains then there is a 99% chance it will be junk because he is nothing more than a surplus reseller.
So it could be a simple over production or all the parts rejected as being defective.

Got the numbers: H70-130215D 8ER-6147D Also on the bottom of the carb it has: Lauson-power product and two small numbers that's 50 Or 05 not quite sure what way its supposed to be read

The original carb for that engine is part number 631912, which is no longer available. When I look at the carb you purchased, it is not a direct substitute. I have tried to locate a carb for you, but have not found one I like. Couple of questions. When you replaced the carb, did you replaced the gasket between the carb and manifold, plus between the manifold and block? Wouldn’t be the first time gaskets look good, but leak. Also, with the new carb, did you go through the adjusting procedure I posted?

It came with a gasket, I attempted the adjustment procedure and miserably failed, lol, it won't even start now, so I need to know a working main jet adjustment so I can get it running at least and try it again, I'll look for the gasket by the block and the manifold, I didn't see if that one was good.

Also, the new carb looks identical to the old one

Hello,

I've found some carbs aren't worth rebuilding (due to corrosion worn choke/throttle shafts etc). On eBay i did a search on "carburetor for a tecumseh H70 engine" and all sorts came up.

I replaced the carb on my troybilt tiller (4 hp) with a cheap eBay carb and it runs fine.

Regards

Jeff

Ah, so this one should run fine then I guess, at least I hope once I get the right adjustment on it

UPDATE: So it turns out the new carb was fine, it was just the gas tank, it wasn't high enough or wasn't even mounted in the right spot the guy I bought it from must have put the gas tank on the side which caused the gravity feed to not work right. My grandpa came and figured that all out as well as tuned it, the thing just digs like a beast now!