Tecumseh 12hp toss-up

Hi guys, I have 2 Tecumseh engines. Both 12hp I believe, the black one is an HH120. The brown one the placard had been painted over looks a bit older (see photo). Both came separately with 2 Power Ponies bought last year (I believe they were the original engines in those tractors which have been repowered with new 17hp Titans). I've never had either running or seen them running.  Both turn over but are a bit messy, both have had the ignition wires chopped out, ones missing a fuel tank, the other an air cleaner and starter...

I've never had one of these non-recoil pull start engines and don't know much about getting small engines going in general lol.

I'm hoping one of the regulars may have experience to recommend if one or both are worth getting going, and testing whether they're runners or not, as my 2024 build off entry Lily comes together. 

Thank you muchly

I'm a Briggs and Stratton guy but have to admit that I have alot of love for those old Tecs, I have 2 and they're both torquey as heck!

My best advice is to remove the heads, set the pistons to BDC and have a look at the bores before deciding on either (feel free to post pics). They're both flatheads (valves in block) so you won't have to worry about that, just unbolt the head and take it off!

The one on the left should be a points ignition and the one on the right a Solid State ignition, they both have their good and bad points. Unless something has changed, last I checked the Solid State coils were made from unobtanium so that's always a worry BUT modern igntion upgrade kits can solve that affordabily. A bad condensor on a points system usually shows it itself before it fully fails and can usually get you back home (probably with cool down rest stops) unlike the Solid State ignition which is more likely to go at all once.

Personally I'll never change a points system to electronic until it becomes a last resort! Lol.

Ditto on the points.

Any ignition problems with that system… it’s the condenser, 99.99999% of the time. Or Dirty points, in which case a nail file, sand paper or a multitool file will get em right again.

Actually the one on the left (brown) is overhead valve. That is the rockers in the the top little box. Looks a lot like the old OH160 I had, but it could be a smaller version the OH120. Coil (solid state magneto) for that one I know are pretty pricey and hard to find sometimes. The flathead on the right I don't know anything about it.

Good point @MightyRaze I forgot about that! Come to think about it I've never had to adjust the valves on mine it's just been a solid running engine.

Thanks for all your input it gave me some confidence to take stuff apart. I didn't want to reply until I had something to report.  Got the head off the brown OHV one, see what you think of the bore I don't think it looks terrible.  The crank has a lumpy feel to it when turned kinda like a stepper motor I guess maybe the main bearings are bad.  Exhaust valve ~.5mm radial play on the inside end seems like a lot.

I've seen worse but with the pitting and gouging you'll burn oil and get gas in your oil, definitely a good canidate for an overbore though. Hopefully the other one looks even better!

On fully disassembling the brown OH one, the piston has a busted skirt so I'd be up for a piston as well, @brianator I take your point about overbore. The 84mm bore tells me it's an OH140 not an OH120 like I thought. The ignition is an epoxy in aluminum potted electronic looking thing without any accessible parts I guess that makes it solid state, looks ok outwardly but no idea if it works. Think I'll clean up parts then park this one while I look for parts and a machine shop and price it up.

As for that "stepper motor" detent feel, one of the magnets inside the flywheel had come unstuck so that explains that (the taper bearings look fine). Assuming I can glue it back down.

I want to open the HH120 up but Im running out of parts storage and bench space. Good motivation to get Lilys peerless 2306 parts ordered and back together though. Thanks guys.

With the "brown" one, the plot thickens, I found the model number stamped in the fan shroud shows OH160. The piston is definitely 84mm though which the Tecumseh manual shows should be an OH140. If I get around to ordering a piston I'll just need to triple check I know what I'm getting...

Brianator wrote:

I'm a Briggs and Stratton guy but have to admit that I have alot of love for those old Tecs, I have 2 and they're both torquey as heck!

My best advice is to remove the heads, set the pistons to BDC and have a look at the bores before deciding on either (feel free to post pics). They're both flatheads (valves in block) so you won't have to worry about that, just unbolt the head and take it off!

The one on the left should be a points ignition and the one on the right a Solid State ignition, they both have their good and bad points. Unless something has changed, last I checked the Solid State coils were made from unobtanium so that's always a worry BUT modern igntion upgrade kits can solve that affordabily. A bad condensor on a points system usually shows it itself before it fully fails and can usually get you back home (probably with cool down rest stops) unlike the Solid State ignition which is more likely to go at all once.

Personally I'll never change a points system to electronic until it becomes a last resort! Lol.

I have one like the one one the left, what is that goofy box thing on the top? I assumed it was crude overhead valve tech, what else would it be for?

The black hh120 I got it cranking but it seems slow even with a new starter and good 330CCA battery. Dribbled some fuel into the cylinder and out the spark plug back couldn't get any pop yet. Then I noticed what looks like a wobble on the pulley which I need to work out is the crank straight... Glad I have a new engine as a backup for Lily! Haven't done a serious search for parts for either yet.

Technochicken yes that top box is the overhead valve cover. It was oily when I took it apart, not sure how the oil gets up there though. Anyway I've boxed all the parts up, if I can find a piston kit I'll have a crack at it.