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Tecumseh Engine Differences?


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#1 CraftsmanGT ONLINE  

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Posted February 10, 2016 - 01:08 PM

Hi everyone, I'm wondering what the difference between a Tecumseh H70 and HM70 is? I'm working on repowering my neighbors snowblower for him which has an H70 with an HM70. I noticed physically they look the same just the governor setup is a bit different and the intake and exhaust are switched around between the two. This H70 is an aluminum bore and the HM has an iron sleeve, and generally I thought all H series were aluminum bores but I've found some with sleeves. If someone could help clear this up that'd be great. I don't see many Tecumseh's anymore and I'm just learning about the model designations. Thanks

#2 dodge trucker OFFLINE  

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Posted February 10, 2016 - 06:20 PM

HM is actually a different engine family, it is a wider block, head is different,  and yes all HM had cast iron sleeves where the H series didn't.  As long as your crank matches up length and diameter wise and is the same height from the mounting surface they should swap out fine.



#3 EricFromPa ONLINE  

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Posted February 10, 2016 - 08:05 PM

Alot of Tecumseh parts are interchangeable throughout there whole engine line.I used a Carb off of a 4hp push mower on a H50 for a while till I found the correct one that was usable.Also used a few governor parts,flywheel,blower housing,coils and recoil starters off of a HM on an H.

 

I'm not certain but I've heard an HM isn't rated for Side load on the crank because it has thinner bearing bosses and thinner case material. 


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#4 Tecumseh power OFFLINE  

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Posted February 10, 2016 - 08:15 PM

Hm is the "medium frame" block. That is why it looks different in size than the H.

#5 dodge trucker OFFLINE  

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Posted February 10, 2016 - 08:47 PM

Alot of Tecumseh parts are interchangeable throughout there whole engine line.I used a Carb off of a 4hp push mower on a H50 for a while till I found the correct one that was usable.Also used a few governor parts,flywheel,blower housing,coils and recoil starters off of a HM on an H.

I'm not certain but I've heard an HM isn't rated for Side load on the crank because it has thinner bearing bosses and thinner case material.

They made versions of this engine a few different ways, that you can't tell from just looking at one. Some had the PTO side crànk bearing as just a machined hole in the cover while other versions of the same engine had bronze bushings here while others had a ball bearing there, those would be the "XL" versions.
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#6 drbish ONLINE  

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Posted February 11, 2016 - 04:18 PM

Here are the Engine specs for the H70 and the HH70 This came out of the Tecumseh engine specifications book
dated 8/81.The book is 81 pages and will attempt to put in the Manual section
Attached File  tec7.pdf   1.68MB   37 downloads
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