Tecumseh won't run past half throttle

[Arkie]

One example on flea bay at this link.

https://www.ebay.com/itm/253374294776?_ ... BM3IqVwvdf

I checked the carb measurements on my old H35 carb that was on the H35 manifold and it has the same mounting dimensions as the one I sent you in the flea bay link for $10.46.
Some of them Tecumsehs CARBS have Lawson Power Products stamped on them and Lawson numbers instead of Tecumseh part numbers, so do not be surprised if you see such.
Get back to us with your results?

If you get a float carb on that rig and still no go, let us know and I'll give you a couple of H35 hints that is easily missed in the service manual that will cause such. (before you give up and throw it in the trash with stomach ulcers bleeding and install a HF Predator @ $100)

[Roadrunner123]

UPDATE: Cleaned the breather and tested it to open and close using a hose that fit over the opening. Worked great. Checked all orifices in the throat and made sure they were clean and sealed the welsh plug. Ran the carb two more time through the ultrasonic. Installed everything and still the same issue.
Now forgive me for not saying mentioning this when the engine dies as I move the throttle to fast it puffs through the carb. The only thing I didn't do is remove the valves and lap them in. I did try to spin the valves when the piston was in the power stroke and I couldn't move them and they were very clean when full open.
There is hope though as I forgot I had a tecumseh six hp that has a bowl carb and it look like it will fit though the top of the throttle is slightly different I think it will bolt on and I could manual open the throttle.
As far as the dimension of my carb. if you go to this link that bgsengine sent me the dimensions are right on. The only thing about the one on this link is the choke lever is 90 degrees different than mine
https://www.amazon.com/dp/B094MV76YT/re%20...%20s9dHJ1ZQ==

[38racing]

I still don't see where you confirmed that valve clearances are in spec.

[Roadrunner123]

I didn't check the clearance but with the piston at TDC I couldn't spin either valve so I thought they should be ok.

[bgsengine]

I didn't check the clearance but with the piston at TDC I couldn't spin either valve so I thought they should be ok.

Bad assumption, they'd only need .0005" clearance to do that... but that's way too little , so that could definitely cause an issue as the engine warms up.. what with you mentioning the pop-back through carburetor, I'd bet you find your valve clearance to be out of spec. also a good time to check if there's any non-seating (tiny piece of carbon stuck between seat and face, will cause valve to not spin, but still be leaking under compression) or burning (notably, exhaust valve, which is burned, can allow "dead" air to be pulled back in during intake stroke, leading to a leaner mixture in combustion chamber than there should be, which can cause surging, overheating, lousy power, hard starting, etc) so yeah a check on the valves may very well be an excellent idea - not only clearances but pull em out for inspection, if you aren't yet ready to try and find a float carb to install...

[Arkie]

I didn't check the clearance but with the piston at TDC I couldn't spin either valve so I thought they should be ok.

Valve clearance is easily checked on that engine.
But if you find a valve that is specs is too close, DO NOT take the stem to a high speed grinder. Just Hand file carefully and check often. The ends of the stems hand file easily. Use a permanent marks a lot pen to color the stem end so as to keep square and each time the color goes away check the clearance.
If too much is taken off you will be SOL. Replacement GOOD Valves are expensive if even found.

If you find one too close in specs you can remove the valve spring and re-insert the valve W/O the spring and check again while pushing down on the valve and then feeler gauge again the difference with the spring and W/O the spring and then you can note the difference for checking your progress W/O having to install the spring each time during filing. (saves lots of time and having to talk to yourself and the Tecumseh during the spring re-install each time to check your progress)

AND if that 6hp carb has adj jets and will bolt up it will most likely give you a idea if it's your old carb for a test run. I'm beginning to suspect your carb is not the main issue with a poor running.
If it don't have adj jets it will probably try to run too rich.

The non-adj jets for a 3.5 hp are rated like 2.5 to 4 hp engines.

[Roadrunner123]

Ok I think you're both right. I installed the bowl carb from the six hp and it does the same thing. The engine is coming off the blower and will be on my bench again today.
I don't have a spring compressor but I saw someone on line doing it with a screwdriver. Any tips on removing the springs if I need to?
Thanks

[bgsengine]

Ok I think you're both right. I installed the bowl carb from the six hp and it does the same thing. The engine is coming off the blower and will be on my bench again today.
I don't have a spring compressor but I saw someone on line doing it with a screwdriver. Any tips on removing the springs if I need to?
Thanks

on those don't really need a compressor, if you have a piece of steel (maybe 1/8" thick, 3/4" wide, maybe 8 inch long) you can cut a 1/4 inch or so slot in one end, and as deep down the center as to just cover the whole valve keeper plus maybe a little extra room, and you have a spring compressor. You can lever it against the valve box to compress the spring (and if you align the keyhole slot in the keeper just right, it'd just about pop right out , align the other way to install, but may need a "push stick" to push the spring/keeper in far enough to hook back over valve stem)

HOWEVER, if you have a 3 piece keeper (keeper and 2 half collars) you'll have a much harder time, and have to drill a access hole (about 3/8 - 1/2 inch or so) at the end of the slot in your tool, and often a helper (kind of need 3 hands when using one of those compressors) , a bit easier with the pinned type keepers, but still harder than the keyhole keepers

[Roadrunner123]

Ok so I have the engine on the bench. First thing I noticed and this is new, that there was oil on the top of the piston. Not sure why and it wasn't there the first time I removed the head. Just thought I would mention that. At TDC the valve clearance was .010-.011 on the exhaust and .080-.090 or the intake. Manual say .040-.010 for both is the range.
I was told by a friend that also works on small engines I should at least lap the valves why I have everything open.

[Arkie]

Ok so I have the engine on the bench. First thing I noticed and this is new, that there was oil on the top of the piston. Not sure why and it wasn't there the first time I removed the head. Just thought I would mention that. At TDC the valve clearance was .010-.011 on the exhaust and .080-.090 or the intake. Manual say .040-.010 for both is the range.
I was told by a friend that also works on small engines I should at least lap the valves why I have everything open.

You have some typo's here.
Make sure you do not use feeler gauges the same size as your typos.

I did not look at the specs but I suspect you mean the specs are .004-.010 for both.

If the ex is .010-.011 this is close enough
AND
.008-.009 is close enough on the intake

if the spec range is .004-.010

On a L-head I would be concerned if I seen anything below .005 because clearance will get closer when hot and the valve are eventually wearing deeper into the seat.
Appears to me you are ok.

If you play around with L-Head small engines very much you need to think about eventually getting yourself a Briggs & Stratton 19063 Valve Spring Compressor @ about $30.

I've used the same one for several years and it sure helps keep you from chewing on your tongue and bleeding when trying to reinstall them spring keepers.

You should re-check your lash to see if you have typos' here. If the ex is .080 someone has already ground too much off the intake valve stem.

You might think about removing the springs and lapping and checking the seats and valve lap pattern on both valves while you have the head off. The valves spring are easier to get off than to re-install.