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Tecumseh Rebuild Options? Or Opinions?


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#16 TAHOE OFFLINE  

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Posted August 21, 2013 - 09:19 AM

I would consider rebuilding if in your shoes, all my tractors except my Massey 1855 and '64 Sears are Tecumseh, I have a feeling I wil have to cross that bridge someday. Parts are getting scarce. One of these days, we are going to have to do some homework and see if any other manufacturer parts will interchange.

I read a year or two ago, some guy found out that an old Lincoln/Ford motor used same rings as one of the tecumseh motors, but can't remember where I read it at.


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#17 superaben OFFLINE  

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Posted August 21, 2013 - 09:28 PM

Howard, the old Tecumseh manual says that the HH120 (specs 120000 series) uses a 32238 piston assembly.

 

The OH120 (specs 175000 series) uses a 34292 piston.  Doug is right, the bore is 3 1/8.  Unfortunately, the pistons are not interchangeable. 

 

Ben W.


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#18 OkieGt OFFLINE  

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Posted August 21, 2013 - 10:20 PM

Howard, the old Tecumseh manual says that the HH120 (specs 120000 series) uses a 32238 piston assembly.

 

The OH120 (specs 175000 series) uses a 34292 piston.  Doug is right, the bore is 3 1/8.  Unfortunately, the pistons are not interchangeable. 

 

Ben W.

Do you have any idea why? Thanks



#19 MFDAC OFFLINE  

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Posted August 21, 2013 - 10:47 PM

 

Of course a harbor freight engine might take away some of the nostalgia of the machine and may not last as long as the orginal engine pulling the weight of a MF tractor. It could last several lifetimes because of how good they are, and of course you could buy another Harbor Freight engine, if for some freak reason the 150.00 lifetime engine gave out, lol.  I'm really not a fan of putting foreign made engines in tractors made by American Union workers, kind of like a insult .I understand repowering if you already have a new engine like Briggs Vanguard or a Kohler Command, but I wonder about the financial wisdom of spending upwards of 1800 on a new twin or 1000 on a new single as much as I wonder about that same financial ramification of a low cost engine. Sometimes you can be penny wise and pound foolish and visa-versa I dont see many 69 Camaros with Kia engines, wonder why? Seems like it happens to old GTs all the time. I have friends that always ask my advice, but in reality they only want me to tell them what they want to hear, we all do that to some degree, catching ourselves doing it may be akin to an epithany. Everyone must blaze their own trail and therefore end in a different Eunomia. Good Luck


I thought it sounded like he was going to have to spend an over 300 bucks to do what he wanted and it also sounded like labor may not be figured in to that. Yeah I hate like hell to have to do that type of a repower with an asian engine but a matter of what I can afford and how bad I need to cut grass or push snow are the main factors why I would consider it. My 2 Massey are my work horses and I gotta do whatever it takes to get them in service again if they break, nostalgia or not. So far I haven't sent any engine money to China on them. I am on some truck forums where you could get crucified for having a Chevrolet engine in a 50's GMC (which I have I'm afraid) so I know what you mean with your Camaro Kia comparison. Just depends on how extreme other folks take things.
 
 

Personally, I'm very leary of putting in a new piston and rings without overboring.  But, I haven't rebuilt a lot of engines either.  My first two Gravelys got rebored by someone who dealt with Gravely engines on a regular basis, with new pistons and rings.  That has been over 15 years ago, and both engines are still going strong.  
 
First, maybe Ben can tell me if that piston will work in my engine.  If not, I may try using a standard size piston to rebuild.


I have dang near zero experience with the HH120's but done a lot of automotive engines and quite a few 5 horse B/S go-kart engines thru the years. If a used cylinder don't have too much taper or a ridge, hone it out and keep the same bore long as possible. Just a measure to make the block last long as possible.
 
 

I totally agree with you about reboring, IF they mic out within tolerances okay, but seriously is ANY 40 year old engine  going to mic out within tolerances, I doubt it. I could see it happening ONLY to a engine that wasn't used or run 75 percent of the time. I could see it more on a walk behind than a rider though, so It could happen, but so could misreading a micrometer, I do it, the guy at the shop can do it, were human. If the parts were more readily available it would be a no brainer as the boring is only about 75.00


I guess my '75 HH120 is only 38 years old--LOL. Dang-it was brand new when I graduated high school---Anyway, I think the standard bore will be ok with it, BUT I sure do understand that my engine is probably the exeption to the rule and normally they just can't be left the stock bore after all those years of use. Since I don't have a dial indicator for cylinders or snap guages or inside mikes, I used the new piston to push a new ring into a bunch of different positions in the bore after I honed it. I kept checking the ring end gap in each position and it was .019 to .020 right on Tec specs everywhere I tried it. Redneck way of doing it but it is a garden tractor, not a race engine.

Later---DAC

Edited by MFDAC, August 21, 2013 - 10:49 PM.

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#20 superaben OFFLINE  

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Posted August 22, 2013 - 06:13 AM

Do you have any idea why? Thanks

 

An OHV will generate more horsepower at a smaller bore than a straight L head will.  The OH120 has a bore of 3 1/8, while the HH120 has a bore of 3 1/2. 

 

Ben W.


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#21 MH81 ONLINE  

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Posted August 22, 2013 - 06:28 AM

In Ryan's tractor, we just honed out and got a new set of rings. It does not hurt for power (probably better now that I remembered to regap the points).

We were able to track down a set of NOS rings, but that was a couple of years ago.
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#22 OkieGt OFFLINE  

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Posted August 22, 2013 - 07:05 AM

 

I thought it sounded like he was going to have to spend an over 300 bucks to do what he wanted and it also sounded like labor may not be figured in to that. Yeah I hate like hell to have to do that type of a repower with an asian engine but a matter of what I can afford and how bad I need to cut grass or push snow are the main factors why I would consider it. My 2 Massey are my work horses and I gotta do whatever it takes to get them in service again if they break, nostalgia or not. So far I haven't sent any engine money to China on them. I am on some truck forums where you could get crucified for having a Chevrolet engine in a 50's GMC (which I have I'm afraid) so I know what you mean with your Camaro Kia comparison. Just depends on how extreme other folks take things.
 
 

I have dang near zero experience with the HH120's but done a lot of automotive engines and quite a few 5 horse B/S go-kart engines thru the years. If a used cylinder don't have too much taper or a ridge, hone it out and keep the same bore long as possible. Just a measure to make the block last long as possible.
 
 

I guess my '75 HH120 is only 38 years old--LOL. Dang-it was brand new when I graduated high school---Anyway, I think the standard bore will be ok with it, BUT I sure do understand that my engine is probably the exeption to the rule and normally they just can't be left the stock bore after all those years of use. Since I don't have a dial indicator for cylinders or snap guages or inside mikes, I used the new piston to push a new ring into a bunch of different positions in the bore after I honed it. I kept checking the ring end gap in each position and it was .019 to .020 right on Tec specs everywhere I tried it. Redneck way of doing it but it is a garden tractor, not a race engine.

Later---DAC

Were the same age, old, lol. I dont mean to sound hypocritical in my assessemnts, maily I care about the old GTs. I think 300.00 was all he was going to spend, plus HIS labor. The main reason I buy super vlean GTs only is that they are only a little more and engine/transmission work isn't a issue.I haven't had one engine/transmission failure in all the years I've owned my old GTs. My 1975 Allis 716H cuts my 2 acres and the PO 2 acres for 38 years, with nothing more than a set of tires, and a battery. To be honest I really dont think the Chinese engines are a good investment in the long run or short run added, that drives 75 percent of my opinion, even more than nostalgia. Sure there cheap, but if you have to remove and replace them every few years, or they dont have the same power, and no way they do unless you move up 3-4 hp, they aren't much better of a option than spending 800-1000 grand on a new 10hp Vanguard or Kohler magnum repower, but I see people with more money than sense do so, I understand spending that much on a tractor I loved, but we dont always do wise things, and hey that's okay, its our money and our machines, everythings good if your happy. This forum is all about help, advice, and sharing opinions, but EVERY one has them and is entitled to them, mine aren/t the right ones, there just mine. Thanks for beng nice about it, sometimes people dont really understand where I'm coming from.


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#23 OkieGt OFFLINE  

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Posted August 22, 2013 - 07:07 AM

An OHV will generate more horsepower at a smaller bore than a straight L head will.  The OH120 has a bore of 3 1/8, while the HH120 has a bore of 3 1/2. 

 

Ben W.

But why should that make the piston different? and why couldn't you bore a Tecumseh to a kohler size?



#24 ARTmf12 OFFLINE  

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Posted August 22, 2013 - 10:14 AM

Does anyone know if a head off a hh100 is the same as a hh120?

Edited by ARTmf12, August 22, 2013 - 10:15 AM.


#25 MFDAC OFFLINE  

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Posted August 22, 2013 - 06:58 PM

 

Were the same age, old, lol. I dont mean to sound hypocritical in my assessemnts, maily I care about the old GTs. I think 300.00 was all he was going to spend, plus HIS labor. The main reason I buy super vlean GTs only is that they are only a little more and engine/transmission work isn't a issue.I haven't had one engine/transmission failure in all the years I've owned my old GTs. My 1975 Allis 716H cuts my 2 acres and the PO 2 acres for 38 years, with nothing more than a set of tires, and a battery. To be honest I really dont think the Chinese engines are a good investment in the long run or short run added, that drives 75 percent of my opinion, even more than nostalgia. Sure there cheap, but if you have to remove and replace them every few years, or they dont have the same power, and no way they do unless you move up 3-4 hp, they aren't much better of a option than spending 800-1000 grand on a new 10hp Vanguard or Kohler magnum repower, but I see people with more money than sense do so, I understand spending that much on a tractor I loved, but we dont always do wise things, and hey that's okay, its our money and our machines, everythings good if your happy. This forum is all about help, advice, and sharing opinions, but EVERY one has them and is entitled to them, mine aren/t the right ones, there just mine. Thanks for beng nice about it, sometimes people dont really understand where I'm coming from.


Yeah old sometimes feels like an understatement!-LOL! No hipocrascy taken, sounds like you stand behind your beliefs to me, just a lot of folks have different situations that make it tough to do what you are able to do. If 3 or 400 bucks is all I can come up with on an engine, that's that. And looking at reality, a 5-10 year engine may be all I can use up at my age anyway! What a person can afford has very little to do with wisdom quite often, it is just what has to happen at the time out of necessity.

Later---DAC
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#26 superaben OFFLINE  

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Posted August 22, 2013 - 08:02 PM

But why should that make the piston different? and why couldn't you bore a Tecumseh to a kohler size?

 

I think you are thinking about the stroke.  Bore is the diameter of the piston, while the stroke is the length that it goes down on each revolution of the crank.  Technically something with different strokes can use the same piston, while a bore difference will be different in piston diameter.

 

You could bore a Tecumseh to a Kohler, but there's a lot more engineering than just bore diameter.  You have to think about piston pin size for the connecting rod, height of piston from the pin to the head surface so it doesn't bang a valve, piston oil ring tolerances to prevent too much oil usage, and skirt length to prevent the crank from whacking it. 

 

Ben W.


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#27 OkieGt OFFLINE  

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Posted August 22, 2013 - 08:47 PM

 

Yeah old sometimes feels like an understatement!-LOL! No hipocrascy taken, sounds like you stand behind your beliefs to me, just a lot of folks have different situations that make it tough to do what you are able to do. If 3 or 400 bucks is all I can come up with on an engine, that's that. And looking at reality, a 5-10 year engine may be all I can use up at my age anyway! What a person can afford has very little to do with wisdom quite often, it is just what has to happen at the time out of necessity.

Later---DAC

How very, very true



#28 OkieGt OFFLINE  

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Posted August 22, 2013 - 08:49 PM

I think you are thinking about the stroke.  Bore is the diameter of the piston, while the stroke is the length that it goes down on each revolution of the crank.  Technically something with different strokes can use the same piston, while a bore difference will be different in piston diameter.

 

You could bore a Tecumseh to a Kohler, but there's a lot more engineering than just bore diameter.  You have to think about piston pin size for the connecting rod, height of piston from the pin to the head surface so it doesn't bang a valve, piston oil ring tolerances to prevent too much oil usage, and skirt length to prevent the crank from whacking it. 

 

Ben W.

I was thinking of using the piston and rod from a kohler, but that would only work if the stroke was the same, that's a longshot or more


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#29 superaben OFFLINE  

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Posted August 23, 2013 - 06:23 AM

I was thinking of using the piston and rod from a kohler, but that would only work if the stroke was the same, that's a longshot or more

 

That would be an interesting experiment to try!  I'm not going to say it won't work, but I would be very careful about clearances and tolerances.

 

Ben W.


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