Tecumseh won't run past half throttle

[Roadrunner123]

thank you so much for that info. Do you know what the correct timing should so I can compare it to may old service manual?
Thanks

[Arkie]

thank you so much for that info. Do you know what the correct timing should so I can compare it to may old service manual?
Thanks

Locate and download the FREE Tecumseh L-head service service manual and look under specifications section and carefully get into the correct H35 column/serial number breakover for correct specs I have the Tecumseh L-head printed version but it's in the shop and cold deep snow to the shop area.
Look carefully. I got on the wrong H35 column once and had to go back for a do over after lots of head scratching. It's easily overlooked.

[Roadrunner123]

Ok thanks. It will be interesting to see if its different from my manual. Thanks will check it out and let you know what I find.

[Roadrunner123]

Why is it called an 'L Head". Though the model number is an H35 the engine is only 2.7 HP. When I downloaded the L Head manual it said 3-11 hp. Are we talking the same engine, meaning do you realize that this is only a 2.7 hp engine?
Thanks

[KE4AVB]

Why is it called an 'L Head".

L-head is one term used the valve layout style. Another couple term commonly used in reference is this design is side valve and flat head. All there terms basically refer to same design. Basic the air flow forms a capital "L" entering and exiting the valves. Also valves are contained in the engine block instead of the cylinder head.

Though the model number is an H35 the engine is only 2.7 HP. When I downloaded the L Head manual it said 3-11 hp. Are we talking the same engine, meaning do you realize that this is only a 2.7 hp engine?
Thanks

Then you go one that is probably labeled net HP instead of gross which Tecumseh used as part of their model numbers until late models when the OHV came along. Those OHV engine I think uses the cc capacity as part of the model number. And the manual is correct if you have a H35 and as Arkie stated there is a serial number on the specs of these engines so you must use the correct column checking the specs.

A good example of this on engines having different hp labels which why several OEM got sued is the case I had here about ten years ago. I had three Craftsman riding mowers at the same engine with the same engine. I mean the Briggs they had on them were the same model and type numbers. First one was labelled 18.5 hp the second was labelled 19.5 hp, and the third was labelled 20.5 hp. Now Tecumseh engines was a dying breed of engines when I came to this field of repairs so I am not that familiar with them but there is a few guys here that are.

We lost T-man which the main Tecumseh tech. I really don't know what happen to him. All I know he was having problems logging on this forum as we convert from Perr forum. As many of us he was of the retirement age so he just decide to move on. He was worth his in gold for knowledge on these Tecumseh engines. Sorely missed.

[Arkie]

Roadrunner:
Your PM question about H35.
One column says 1982 and prior the other says 1982 serial
no.. What does 1982 serial no. column mean?

I'm not looking at the manual just trying to give you a hint from past experience when timing a Tecumseh H35. Someone had been into mine before me and had the timing off and also had a bad carb and a bad magneto. Main issue was a weak magneto. Would run but not throttle up and I could not replace the engine because it was on a generator and the Tecum gen version engine have a special crankshaft taper.
I got in the WRONG column in the specs section and timed the engine wrong. After the engine would not run correctly I had to determine the year of my engine and get in the correct spec's column after I installed a new magneto.
You will have to determine the year going by your serial number and if lucky yours will be before 1982. I finally figured out mine was a 1982 and had to use the 1982 and later column.
You will have to go to the section that explains how to interpret the ID info to get the year of manu.
As KE4AVB mentioned their was a guy on the Perr forum and he came here for awhile by the name of T-man, he was a Tecumseh factory trained expert and he took it personally if someone bad mouthed any Tecumseh.
I still run several of the Tecumseh's for myself, but parts are NLA or hard to find and expensive and I just usually replace them with a Briggs or some guys go to the HF Predator $100 engines.
A place by the name of m&d mowers had or has a good Tecumseh parts reference page by model number to get IPL's maybe at this link https://www.m-and-d.com/Tecumseh_parts.html
where you can sometimes get Tecumseh part numbers and then search on-line using part numbers or go to flea bay.
Also check out m&d.com home page for transaxles parts such as Peerless/Tecumseh or vice versa and lots of other info from the home page.

Summary: The timing is critical on the H35 and (the H=Horizontal crank and the 35=3.5hp when looking in Tecum specs section manual even though it may figure out different in cc/hp.
You will have to use a continuity light or a ohmmeter per the instructions in the manual when setting the points per BTDC of piston and just tightening the plate screws will change the setting. (so patience is required) You also have to keep a heads up when re-installing the flywheel the stepped key has to be turned correctly or it will rub on the points box cover and the key has a tendency to be forced out of the crank slot (pushed back too far) as the flywheel is installed. On my Tecumseh engines I drill and tap the flywheel after it's off for using a flywheel puller instead of using the whack and bang method of flywheel removal.

[Arkie]

Here is a m&d link to the IPL for your engine.
http://www.m-and-d.com/pdfs/Tecumseh/H35-45503M.pdf

and you need to hang onto that carb if you work on small engines even if the engine goes away.

I've installed that Tecumseh carb as a direct bolt on onto some Briggs engines that Briggs carb are obsolete and vice versa.

[bgsengine]

Roadrunner:
Your PM question about H35.
One column says 1982 and prior the other says 1982 serial
no.. What does 1982 serial no. column mean?

Just to add to this , the "serial" they refer to in manual, etc can also show on the model information label as the "DOM" (Date of Manufacture) on your older engine (and assuming it is original to your 1978 Ariens) you likely have a date code starting with 7 or 8 most likely - such as 7129J which would be interpreted as 129th day or 1977 (or 1987, or 1967, etc, but definitely not 1987 since they stopped using breaker points in the mid-1980's) So long as your DOM doesnt start with a 2 or 3 , you're probably OK to assume it is 1970's era based on your machine date, assuming it is original engine to the machine...

[Roadrunner123]

Here is a link to a photo of my engine cover that makes working on this engine confusing as far as model and hp rating.
If you zoom in on the picture you will see the model as H35-45503M s/n 8110B which according to the Tecumseh manual is a 3.5 hp motor yet look at the sticker on the cover.
I have been unable to find any info. the refers back to a 2.7 hp tecumseh engine with an H35 model number
https://photos.app.goo.gl/Xg51Ju73M6rbxoTx6

[Roadrunner123]

I did loosen the stator plate when I installed the points but even though I circled the bolts with a magic marker so as to make sure its was put back in the same spot,

never works, even when I used to actually take a chisel and "stake" a v-notch into the stator and block, even a slight bit out of place (just a bump while bolts are loose) can change timing by several degrees.. and thermal expansion can cause it to move or shift (and bits of dirt and crud that might fall in between stator and block cause bolts to come loose after the crud crushes or embeds) I'd check point gaps first (just to see if it has shifted at all) and cleasn the points, just to verify , before going deeper and re-setting timing... - one thing at a time... Though if the head hadn't been off before, and you do plan to pull it, you might do a top end service (de-carbon, clean valves, check clearances, make sure there's nothing causing valves to stick, etc) while you have it off

Update:
So I removed the head so as to be able to check valves , clean piston and head and also to check and or adjust timing with a dial indicator. Found something very interesting!
So the points were still set to .020 according to specs and I readjusted the timing which by the way landed exactly on the witness marks made by the star washer behind the head of the bolts holding the stator in place. I'm including a link to show you the crank shaft and two interesting marks. One mark (diamond shape) as we all know is the highest point of the load where you would position the end of the points the other marks are two parallel lines just above the diamond where the point end now ends up when the timing is correct at .065 B.T.D.C.. Coincidence or did Tecumseh put those marks there on purpose to help get the timing correct when the stator plate is moved??
I personally don't think it's a coincidence but would be interested if anyone else has noticed this?
https://photos.app.goo.gl/uwy3hhfaUSDnCDvv9