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Need Help With Dimensions Of Hh120 Camshaft


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#1 MFGray OFFLINE  

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Posted September 08, 2013 - 08:35 AM

I have a tecumseh HH120 with the exhaust valve at 28 thou - it should be set at 20 - and I suspect the camshaft lobes may be worn down a bit. The Tecumseh 8-18HP manual says that the VH80, VH100, HH80, HH100 and HH120 all have the same camshaft lobe nose-to-heel measurement - between 1.3045 and 1.3085. I have measured two of mine and they are both about 10 thou more than that - around 1.314 - 1.315. That seems to be in the range for the OH120, OH140 and OH160, which according to the manual have a nose-to-heel measurement of between 1.3117 and 1.3167. Either I have managed to pick up two OH camshafts, or I am measuring them wrong, or it might be a misprint in the manual. Please does anyone have an HH120 they could measure to check? I have tried looking up the parts numbers but there are too many different versions for me to be sure which ones might be which diameter. Thanks!


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#2 MH81 OFFLINE  

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Posted September 08, 2013 - 09:36 AM

I have an old cam out of a 67 HH100 I'm hanging on to for Ryan if he ever needs it.
If its the same, be glad to go measure.

This is what you need to measure, right?

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#3 MFGray OFFLINE  

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Posted September 08, 2013 - 09:51 AM

Yes - that's exactly right. It should be easy enough to measure it, I thought I had made sure that the calipers were straight across the profile and perpendicular to the shaft, but now I wonder if I was holding them crooked. I would be interested to see what you find - many thanks!



#4 MH81 OFFLINE  

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Posted September 08, 2013 - 10:02 AM

I got 1.28 max on that lobe and 1.27 (excluding comp release) on the lobe closest to gear.
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#5 MFGray OFFLINE  

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Posted September 08, 2013 - 10:57 AM

Thanks for checking, that seems a bit below the minimum specs. Was it the camshaft in your picture that you were measuring?



#6 DH1 OFFLINE  

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Posted September 08, 2013 - 12:14 PM

1.311 

1.314

Exhaust lobe on 2 different camshafts.

 

I have spares if you need one.


Edited by DH1, September 08, 2013 - 12:14 PM.

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#7 MFGray OFFLINE  

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Posted September 08, 2013 - 12:54 PM

Thanks Doug, both of yours are similar to mine - significantly bigger than the manual says they should be. I am guessing the measurements for the HH100 and HH120 should be the same as those for the OH engines but somehow the figures for the VH engines were put in the HH section of the manual by mistake. Your measurements give me the confidence to use my own spare, but thanks for the offer!



#8 Canawler OFFLINE  

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Posted September 08, 2013 - 03:38 PM

I'm working on my HH120 as we speak.  Both lobes are 1.312


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#9 MFGray OFFLINE  

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Posted September 09, 2013 - 07:07 AM

That's five camshafts (including my own) from HH120 engines with lobes that are three to seven thou wider than the unworn dimensions in the Tecumseh 8-18 HP manual. I think that is quite conclusive. Thank you.

#10 MH81 OFFLINE  

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Posted September 09, 2013 - 07:20 AM

Thanks for checking, that seems a bit below the minimum specs. Was it the camshaft in your picture that you were measuring?


Oh no, it was just a used one from a blown engine on the shelf.

#11 DH1 OFFLINE  

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Posted September 09, 2013 - 07:41 PM

That's five camshafts (including my own) from HH120 engines with lobes that are three to seven thou wider than the unworn dimensions in the Tecumseh 8-18 HP manual. I think that is quite conclusive. Thank you.

 

The spec in the manual is it a minimum dimension?



#12 Canawler OFFLINE  

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Posted September 09, 2013 - 08:20 PM

http://gardentractor...hh120-overhaul/

 

This manual has the correct spec.


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#13 MFGray OFFLINE  

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Posted September 10, 2013 - 02:20 PM

I think the spec in the manual is a range starting at unworn (1.3085) and going down to the minimum size considered effective (1.3045) as the lobe wears - at least that is my interpretation. I can't see how the HH120 camshaft lobes could possible get bigger,  yet most of the ones measured exceed the maximum (unworn) dimension given in the manuals - including the one kindly referenced by Canawler. They do however fit right into the range for the OH engines.



#14 Canawler OFFLINE  

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Posted September 10, 2013 - 03:26 PM

 - including the one kindly referenced by Canawler.

 

Wow.  I must have been spacing.  For some reason I had it stuck in my head that you were saying the manual spec was off by several tenths.  I posted that one as it was within a few thousandths.






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