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Discussion Starter #1 (Edited)
picked this up recently for a song. when I see guys putting Chinese engines in their vintage machines, I wonder why they don't hunt around and get a vintage block like this. it cost only $40 shipped to my doorstep, from an engine shop that closed down.

it's got 2 output shafts, and has HM80 8HP bore/stroke dimensions. it was a new block that a dealer/repair shop had in stock, that they never used.

this sucka is cherry !!:) turns really smooth. the output shaft dimensions may be wrong for a snowblower, but I figured worst case can just pull the rod/piston/ring assembly out and drop that into one of my HM80 machines to freshen it up, if need be.

or maybe take a bona fide HM80 crank from another machine, and drop it in this block to make the output shaft correct- but the shaft may work as is, haven't checked it yet against other ones

any opinions on the output shaft size ?







 

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Discussion Starter #2
it's interesting to turn it over, and watch the valve movement- it has what I believe is a built in compression release bump on the exhaust valve. as the piston comes up to TDC on compression stroke, the exhaust valve opens for just a moment to let some compression OUT. then the ex. valve opens again later on exhaust stroke. otherwise you'd never be able to pullstart the engine, it would snap the rope, or rip the handle from your hand. it you ever tried to start a Briggs with a defective compression release part inside, you know what I mean. it will pull then suddenly jams up like a seized engine and will rip the pullstart handle from your hand (sometimes painfully so)- but in reality, it's the compression of the engine stopping you from pulling the pullstart.





 

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That is a great find.
 

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Looks just like an hmsk80 short block.I pulled one from a mid 90's MTD. If I'm right the crank is bored at 5/8 and the cam is flat on 2 sides. $40 delivered is a rare find. Congrats.
 

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I have zero idea how to re-power an engine. I've got a 5HP HS50 (working, hopefully I'll never have to swap it out). How do I know which other HS series will fit my machine? I don't really want to mess with different shaft lengths, etc... but I do want to up the HP if I ever do swap it.
 

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I have zero idea how to re-power an engine. I've got a 5HP HS50 (working, hopefully I'll never have to swap it out). How do I know which other HS series will fit my machine? I don't really want to mess with different shaft lengths, etc... but I do want to up the HP if I ever do swap it.
Most new engines come with diagrams for all the various sizes of parts. Just take your old engine off and measure the critical stuff like crankshaft height, length and diameter. Also measure the base plate bolting pattern.
 

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Discussion Starter #7
I have zero idea how to re-power an engine. I've got a 5HP HS50 (working, hopefully I'll never have to swap it out). How do I know which other HS series will fit my machine? I don't really want to mess with different shaft lengths, etc... but I do want to up the HP if I ever do swap it.
I believe all the Tec. engines of that era had the same bolt patterns on the base, and same shaft heights. Or so darn close they will work and interchange. The only way to find out for sure, it break the tools out, and take it off the machine, and compare. If you get stuck, find someone with mechanical knowledge to help you. Working on stuff like this isn't something you learn overnight, it's a long process and you never stop learning. Don't be afraid to make mistakes because that's how you learn. It's only a snowblower, these used machines are quite cheap, and you can afford a mistake. Just make sure you have no safety issues when re-assembling.

there's a site I found with a lot of Tec. info on bolt patterns, etc. I'll find the link and post it.
 

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