# Noma N1232EL with Tecumseh OHSK120 adjustments



## xp190 (Jan 15, 2011)

Howdy

I have this old snowblower I got from a friend, great machine, but the engine runs a bit rough, it misses every now and then, it's most visible on idle, and it backfires from time to time.

The carb was leaking, so I got a kit for it and rebuilt it, now when I start the engine it goes all the way to full throttle and I can't calm it down.

There is a distributor on this machine, there are a few adjustment screws on it but I have no idea how to work this thing to get it to calm down a bit.

I think it might have been heavily tampered with by the PO in order to keep it running, now putting it back might be an issue.

I was wondering if anyone could point me in the right direction on how to calm this beast down and even get the throttle lever to do anything at all, right now no matter where it is set, it goes to full throttle.

I can post some pics of the adjustment screws if it will help.

Thanking you in advance

xp


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## 30yearTech (Sep 14, 2006)

The first thing to try would be a static governor adjustment, that is assuming that the linkages are attached correctly and the governor working. You can find links to service manuals in the sticky thread in the 4-cycle section labeled "Helpful Links"


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## xp190 (Jan 15, 2011)

Hi

going through the manuals right now, but it seems this engine is not that well documented, the specific governor it uses it not explained very well.

I'm fiddling with it, I'll post my findings, but any tips would be appreciated 

Thank you

xp


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## usmcgrunt (Sep 16, 2007)

Here is a copy of the manual.If it is different from the one you have,then it may help you.Good luck.

http://www.mymowerparts.com/pdf/Tec..._OVRM120_OVXLC120_OVXL120_OVXL125_695244A.PDF


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## xp190 (Jan 15, 2011)

Well, it looks like my governor failed, after rebuild the carb, it no longer adjusts rpm and the engine over revs big time.

I'd like to fix this machine up as I will be needing it at my property. Would anyone happen to know a good place for parts for an OHSK120 and perhaps a shop manual or maybe a rebuild guide even?

Would greatly appreciate it.

Thanking you all in advance

xp


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## 30yearTech (Sep 14, 2006)

If the governor failed, you will need to pull the sump cover off of the engine and have a look to see what parts you may need. 

The link in the post just above your last entry has a link for a service manual for your engine.

There are numerous places online to obtain parts for your engine, below are a few places you can look.

http://www.partstree.com/parts/
http://www.searspartsdirect.com/partsdirect/index.action
http://www.jackssmallengines.com/


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## xp190 (Jan 15, 2011)

Thanks a lot 30yearTech

I took the engine off the blower and took it apart. It looks like everything is in order, the governor parts are in good shape, I must have not set it up correctly. At first sight the workings of it are a bit confusing but I think I figured it out.

Now the engine misfires, and it gets worse as it warms up. From the research I've done it could be carbon buildup or spark plug. Well the exhaust valve is heavily covered with carbon, but otherwise seems fine.

What is a good safe way to clean up the carbon? Scrape off with a piece of wood?

I have the engine almost fully disassembled, the only parts still together are the cylinder head and rocker box. As soon as I have the intake valve spring off, the box will come off and the head will follow. I'd like to check this engine for proper specs all around.

Thank you for the parts links, I will be ordering a few items, but out of curiosity, would you be able to recommend any parts that I should replace regardless of their condition?

So far I only have the gasket and seal set on the list, I'm thinking of ordering an extra camshaft key even though mine looks good. I don't have tools to cut valves and valve seats and I hear lapping is a waste of time, any recommendations? I'd like to have this thing running as I will need the blower on my property.

Regards and Thank you for all your help

xp


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## 30yearTech (Sep 14, 2006)

Cutting or refacing the valves and seats are only required if there is damage to them. Carbon can be cleaned with a wire brush, or you can soak carbon over night with sea foam or another type of cleaner and then scrape and wipe the carbon off.

Check the valve lash on the valves. Lapping the valves will insure that there is a good seal between the valve and seat. Lapping will also aid in telling if the valve and seat are making good contact all the way around. I generally will lap the valves if I take them out for any reason.


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## dj722000 (Oct 29, 2008)

xp190 said:


> I don't have tools to cut valves and valve seats and I hear lapping is a waste of time, any recommendations?


Lapping valves with the idea you will correct a non sealing seat, or one thats not concentric is a waste of time and will not work. (Firstly, this is not what it is for)

I use it to mostly clean up the area after a removal and installation of valves.

I think what you heard was geared more towards automotive engines which is almost not heard of anymore because of technology and the metals they are using.

Other then that I believe 30yeartech is right.


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## xp190 (Jan 15, 2011)

Thanks guys

That is true, I heard lapping is a waste of time on automotive engines although at one point I was planning on doing it myself on a 4 cylinder engine I was rebuilding.

I took the engine apart completely, the exhaust valve was heavily coated with carbon and a collar formed on it. I cleaned it up, now it looks good as new. The exhaust valve did have some scuff marks on it on both ends, seems like lack of oil at some point, everything else looks good.

The valve guides have a bit of play in them, but I don't think I want to replace them, I think they should be fine, this is not meant to be a high end engine, I just want it to run without missing.

I'll be ordering a seal kit for it as it seems there are quite a few high temp orings there that I don't have, the head gasked seems like it can be reused, but the kit will come with a new one so I will replace it either way.

Overall this is a very nice engine, I hope I get a lot more life out of it and lots of snow moved out of the way.

xp


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## dj722000 (Oct 29, 2008)

xp190 said:


> Thanks guys
> 
> I took the engine apart completely, the exhaust valve was heavily coated with carbon and a collar formed on it. I cleaned it up, now it looks good as new. The exhaust valve did have some scuff marks on it on both ends, seems like lack of oil at some point, everything else looks good.


 Could be that carbon got down in around the stem of the valve and scratched it. If there is alot of carbon on exhaust, take a good look at your piston and rings. Sometimes this could be oil getting past the rings and burning itself to the valve. Also look at the cylinder bore, make sure it is round and isnt oblonged.

This could also be from the exhaust guide being to worn allowing oil to come up past stem and burning to the valve itself.



xp190 said:


> The valve guides have a bit of play in them, but I don't think I want to replace them, I think they should be fine, this is not meant to be a high end engine, I just want it to run without missing.


If they go side to side alot, you may end up binding the valve. Right back where you started from. If there is significant side to side play, this could cause missing as the valve wont close up all the way.




xp190 said:


> I'll be ordering a seal kit for it as it seems there are quite a few high temp orings there that I don't have, the head gasked seems like it can be reused, but the kit will come with a new one so I will replace it either way.


If you got a kit, replace all of the gaskets and seals. Do not reuse any of them Especially the head gasket.


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## xp190 (Jan 15, 2011)

Thanks for the feedback DJ

I ordered a kit and plan on replacing all the seals and gaskets.

I think I will replace the valve guides as well if it's going to cure the missing issue.

Once the new valve guides are in, do I need to cut the valves or seats, or would lapping be fine?

Thank you

xp


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## 30yearTech (Sep 14, 2006)

xp190 said:


> Thanks for the feedback DJ
> 
> I ordered a kit and plan on replacing all the seals and gaskets.
> 
> ...


Lapping should be fine as long as the valve and seats are making contact all the way around. As stated in my previous post, lapping will show if there is any area of the seat that is not making good contact with the valve.


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## xp190 (Jan 15, 2011)

The new parts arrived, I managed to get the new valve guides into the cylinder head last night, there is visibly less side to side play with the new valve guides, I think this is a very good sign. I'll pick up a valve lapping tool today after work to make sure everything fits nicely and put the engine back together over the next few days.

I hope this will have it running like new again, it would make my day for sure.

Would investing in a valve seat cutter and vale refacing tool be a good idea, taking into consideration that I have quite a collection of small engines, which grows every year, and that I enjoy working on them?

Would anyone be able to recommend a good all around valve seat cutter/refacer for the DIY type? Would appreciate it.

Cheers

xp


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## 30yearTech (Sep 14, 2006)

These tools are kind of expensive, and at least for me are rarely used. I have them, (but this is what I do for a living) I may only use them once a year or s0. I don't think I would recommend them for someone just maintaining their own equipment.


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## xp190 (Jan 15, 2011)

Hi 30yearTech,

yes you are right, some of these tools are very pricey, but there are also some hand tools for a much lower cost which are said to be decent. Maybe I'll find someone with a machine shop and see if I can get them to check any valves I might have over.

Anytime I take an engine apart, I feel bad putting it back together if I know there are things I could fix up, but with today's manufacturing, a new engine will cost you $300, so maybe it's not worth even fixing anymore.

xp


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## 30yearTech (Sep 14, 2006)

I know what you mean, I just purchased a new impact driver because the switch on mine has a dead spot. The switch cost more then half of what a new driver cost, not to mention the amount of time to take it apart and repair. 

These small air cooled engines are for the most part not very high tech and are fairly forgiving if you can just get close to the proper settings and tolerances. I never really run across much damage to valve seats, mostly it's the valves and they are generally not too expensive to replace if the valve face is damaged.


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## dj722000 (Oct 29, 2008)

If what your working on is the smaller engines, then no, I wouldnt recommend buying these tools. But if you have some of the bigger engines around like a 10 hp and higher and they need work, then possibly buy the tools at your discretion. I like 30yeartech and several others have them, but I rarely use them. I have them because I do alot of work on some bigger engines and alot of the older K-Series engines. (Engines that are worth the repair you could say, hard to explain to someone they owe you $350 for a $100 engine.) It actually took me sometime to buy some of the pricey stuff, I only bought them when I actually needed them.


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## xp190 (Jan 15, 2011)

Thanks for the good words of advice guys, I really appreciate it.

One interesting item I came across, the manual for the engine says to never lap the valve seats, always cut them. I lapped mine as per 30yeartechs advice, and they seem to be sealing much better, but why such harsh instructions against lapping? Could it hurt something in any way?

As for the tools, I'm not going to run out and buy brand new sets, I have a few friends that are long long time collectors of engines and tools, and I might be able to get something used in decent condition for a fair price, so I was just wondering if it would be worth holding on to if such an opportunity come up, it seems it would be, so I will keep an eye out for valve tools.

One other note, I was checking all the specs on the engine, and I noticed the valve springs are about 46-47mm which is short of the 50.292mm the manual specifies. I'm not 100% sure, but this sounds to me like it could be one more reason for the engine missing.

I will put it back together, and give it a run see how it behaves, if the problem is still there, I will replace the springs since they are very likely a problem of sorts, if it runs good and the missing is gone, I will be one happy camper 

A day or two more and I should have results, I will let everyone know.

Thanking everyone in advance yet again

xp


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## 30yearTech (Sep 14, 2006)

As long as you get the valve lapping compound cleaned up good, there should be no detrimental effect from lapping valves. I always lap the valves, especially after cutting the seat, to insure that I have a good even seat all the way around the valve seat. I have never had any issues after doing this.


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