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Tecumseh HH80 Timing Help

tecumseh timing hh80

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#1 NUTNDUN OFFLINE  

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Posted September 25, 2015 - 07:23 PM

We are working on a Tecumeseh HH80 that is in a little Massey Ferguson 8 Hydro. I had finally gave in an removed the head to check that the crank and cam were at least close to where they needed to be without tearing it further apart.

 

I have the flywheel off and for lack of the correct name, stator assembly maybe? The bolt holes are slotted. I checked to see when the points would open when the piston was near TDC. They don't open until after TDC and the piston is already 3/8" down the bore. To me this doesn't seem right. The points are operated from the lobe on the crank. Should the points be breaking before TDC or is breaking after TDC correct?



#2 Bruce Dorsi OFFLINE  

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Posted September 25, 2015 - 07:39 PM

According  to the service manual, points should be set at .020", and timing is set at TDC.  ,,,,,,Running spark advance is .095" before TDC.



#3 NUTNDUN OFFLINE  

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Posted September 25, 2015 - 07:54 PM

My suspicion seems to be correct then that something is wrong with the setup on this thing. Where the lobe is on the crank and where the points contact that lobe the closest I can get to TDC when the points just start to break is with the piston already 3/8" down the bore on its down stroke.



#4 olcowhand OFFLINE  

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Posted September 25, 2015 - 08:15 PM

Sounds like maybe someone set the camshaft one tooth off.

#5 glgrumpy OFFLINE  

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Posted September 25, 2015 - 08:40 PM

You sure you are turning crank right way, heh! Maybe that is the Advanced timing, not After?  Just checking, have messed up simple things myself like that. Besides, I didn't think there was any real timing to set on the engines, cept by point gap. Did you try .018 or some other setting? Seems .020 would be for New points if like on Kohlers, and then set tighter on used points. Using good gauges and techniques?


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#6 MH81 ONLINE  

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Posted September 25, 2015 - 08:57 PM

Sounds like maybe someone set the camshaft one tooth off.

but the points on this are on the crank.  Is there anything else wrong that you can see?  is it possible the crank is twisted?


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#7 Bruce Dorsi OFFLINE  

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Posted September 25, 2015 - 09:32 PM

Does this engine have a removable lobe, like some other Tecumseh's ?  ...Maybe someone installed the wrong lobe ????

 

What is the history on this engine ?  .....Did you ever hear it run ??



#8 FixItCharlie OFFLINE  

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Posted September 26, 2015 - 11:48 AM

Do the point open with contact to the cam lobe or do they use a push pin. Is it possible that where this rides worn on the cam lobe. I know on some Kohler motor that this has happened. For this reason when ever I adjust the points I always check it by hooking up the timing light to verify the timing.

 

Charlie



#9 DH1 ONLINE  

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Posted September 26, 2015 - 01:48 PM

Does this engine have a removable lobe, like some other Tecumseh's ?  ...Maybe someone installed the wrong lobe ????

 

What is the history on this engine ?  .....Did you ever hear it run ??

 

Ditto  did you ever hear this engine run?



#10 NUTNDUN OFFLINE  

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Posted September 26, 2015 - 01:56 PM

The lobe on the crank is definitely not removable. I don't know much on the history of the motor and have never heard it run other than what I have gotten out of it which isn't much. It is definitely out of time whether it is the points or the cam. I did take the head off and rotated the engine a couple of revolutions just to check that the valves were opening and closing when they should and it seems like it is good with the cam.

 

I did unbolt the motor from the tractor and will probably break the case open just to double check the cam. 

 

Did Tecumseh make any of the H80 engines that ran CW instead of CCW? It almost seems like the crank might be for a CW engine with where the lobe is located for the points.



#11 DH1 ONLINE  

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Posted September 26, 2015 - 02:25 PM

I think they all run CW looking at the top of the flywheel.



#12 olcowhand OFFLINE  

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Posted September 26, 2015 - 07:38 PM

I think they all run CW looking at the top of the flywheel.

Yep


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