# Tecumseh/Craftsman Engine



## Spit (Nov 3, 2006)

I have a Craftsman 21 inch push lawn mower with 6HP Tecumseh mand engine. Engine Model Number 143.996004. 

I was just given the mower and it had not been run in some time. I was trying to clean up the carb and finally got the bottom nut/venturi cleaned out. But I could not get the mower to run anywhere near high RPM. Then I noticed that the blade was severely bent, but the crank shaft seemed okay...so I put a old 20 inch blade I had laying around on the mower and still it would not run at high speed, I did get an occasional backfire. So I checked the flywheel key and sure enough it is/was sheared. I just got a key today and have not had a chance to change it yet. 

I have a couple of questions: 

1. Would the engine being out of time due to the flywheel key being sheared cause it to run a low rpm? Or might I still have a carb problem? 

2. This carb has a capped adjustment screw for the low speed? 
what is the correct setting for that screw? 1 1/2 turns out? 

3. One more dumb question...about the plastic nozzle in the center of the carb...with the 2 o-rings. are there different sizes of those? It had a green one in it, and I replaced it with one from a junk carb I had laying around, the one I put in was red and it seemed to be identical..but maybe is a fraction of an inch shorter? I could take the red one out and remove the orings from it and put them on the original green one if this height difference is a problem

4. Can anyone tell give me the cross reference to what Tecumseh model # engine this is, or tell me what the valve lash should be?

Spit


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## 30yearTech (Sep 14, 2006)

Spit said:


> 1. Would the engine being out of time due to the flywheel key being sheared cause it to run a low rpm? Or might I still have a carb problem?
> Spit


A sheared flywheel key can affect the top running speed of an engine. This does not mean that you still do not have any carburetor issues.



Spit said:


> 2. This carb has a capped adjustment screw for the low speed?
> what is the correct setting for that screw? 1 1/2 turns out? Spit


Your carburetor shows to be a fixed jet and should not have any adjustments to the main jet or low/idle speed circuit. If your referring to the screw under the plastic cap on the side of the carburetor, this is not an adjustment, just the pilot jet that can be removed for cleaning. It should be screwed in snug.



Spit said:


> 3. One more dumb question...about the plastic nozzle in the center of the carb...with the 2 o-rings. are there different sizes of those? It had a green one in it, and I replaced it with one from a junk carb I had laying around, the one I put in was red and it seemed to be identical..but maybe is a fraction of an inch shorter? I could take the red one out and remove the orings from it and put them on the original green one if this height difference is a problemSpit


The nozzle with the O ring is sized to the carburetor for the specific application and they are color coded. They are interchangeable, but you need the one for your specific engine. 



Spit said:


> 4. Can anyone tell give me the cross reference to what Tecumseh model # engine this is, or tell me what the valve lash should be?Spit


143.996004 --> LEV115-360021C


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## Spit (Nov 3, 2006)

*The flywheel key did it*

30 year tech, thanks for answering all of my questions. I put the flywheel key in and it fired right up and ran at full speed and seems to run just fine. Spit


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## 30yearTech (Sep 14, 2006)

Glad to hear everything worked out well for you. :thumbsup:


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