Tecumseh H70 vs HM70

[Craftsman GT]

I'm wondering what the difference between an H70 and HM70 is? I'm working on repowering my neighbors snowblower for him, it's a late 60s MTD Snow flite with a Tecumseh/Lauson H70 that is plain wore out and the shroud has rusted thru in a few places. I have a strong running Tecumseh HM70 I was going to put on it. Any major differences between that and the H70? So fsr I've noticed the governor setup is a bit different and the intake and exhaust are switched around between them. Thanks

[bgsengine]

the "M" in HM70 refers to "Medium Frame" tecumseh engine - as you noted there are some external differences, and I believe the valves and internal parts are different - main thing it refers to would be the fact of the cylinder liner (Cast Iron liner) - the HH70 will be a "heavy frame" engine and the block is all cast iron as long as the engine bolts in , crank dimensions are correct, etc it should not matter if you are replacing the whole engine.

[Craftsman GT]

Thanks BGS. I got the engines swapped and the blower is back in service. From what I was able find some H series have aluminum bores and some have iron sleeves, it gets confusing. I have always wondered why some Tecumseh's have the intake and exhaust switched around?