# hmsk80 vs. hmsk100



## cadmobile500 (Feb 15, 2015)

I blew the engine in my mtd 10/24 snow blower last year. it originally had a hmsk100 but all I could find at the time was a hmsk80 to replace it with. the hmsk80 I bought blows away the hmsk100 that was originally on the blower but I also turned the governor on it up to 3600rpm. im assuming the hmsk100 was down on power since it had the original oil from 2003(blower was given to me) and seized. im wondering if it would be worth it to find another hmsk100. is there a noticeable difference in power? ive already installed an impeller kit and have a 1/2" larger engine pulley to spin the auger impeller faster on the way. the hmsk100 makes an additional 3ft/lbs of torque and is 40cc's bigger. opinions? I really want to throw some snow since my driveway is 5-6 cars wide and I can only throw in one direction. thanks in advance.


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## Shryp (Jan 1, 2011)

24" blowers normally have engines between 5 and 8 HP. Distance is a factor of tight impeller tollerances (impeller kit), impeller rpm (oversized pulley) and clean slick chutes (sand, paint and wax).

The larger impeller pulley might benefit from a larger engine if you have a lot of heavy snow and the engine is bogging down. If your engine doesn't bog down then more power will do absolutely nothing for you.


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## Pathfinder13 (Feb 28, 2014)

I understand the nice feeling of having a little power to spare as I like that too, but that 8 should do just fine if the impeller bearing is good, and the impeller kit is installed to sweep clean with minimum drag. It should keep you happy.


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## greatwhitebuffalo (Feb 11, 2014)

cadmobile500 said:


> I blew the engine in my mtd 10/24 snow blower last year. it originally had a hmsk100 but all I could find at the time was a hmsk80 to replace it with. the hmsk80 I bought blows away the hmsk100 that was originally on the blower but I also turned the governor on it up to 3600rpm. im assuming the hmsk100 was down on power since it had the original oil from 2003(blower was given to me) and seized. im wondering if it would be worth it to find another hmsk100. is there a noticeable difference in power? ive already installed an impeller kit and have a 1/2" larger engine pulley to spin the auger impeller faster on the way. the hmsk100 makes an additional 3ft/lbs of torque and is 40cc's bigger. opinions? I really want to throw some snow since my driveway is 5-6 cars wide and I can only throw in one direction. thanks in advance.


this past week I did some of those exact tests, the AMF 8HP Tec. vs. the AMF/Craftsman 10HP Tec. 

the 10HP engine cut through the frozen 14" snow better than the 8HP, and when it hit the deep frozen stuff, the 10HP was not pulled down in rpm a much

the 8HP was close but the 10HP was noticeably more powerful.

you discovered a well kept little secret amongst snowblowers and small engines- reset the governor WOT speed higher and you get more performance from the machine. the factory governor settings are always on the conservative side. the engines are capable of more rpm and power within sane limits. they keep the rpm down to extend engine life and limit warranty work issues.


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## Shryp (Jan 1, 2011)

greatwhitebuffalo said:


> you discovered a well kept little secret amongst snowblowers and small engines- reset the governor WOT speed higher and you get more performance from the machine. the factory governor settings are always on the conservative side. the engines are capable of more rpm and power within sane limits. they keep the rpm down to extend engine life and limit warranty work issues.


The other thing is the governors are controlled by springs. As the springs get older they get stretched out and loose tension which slows the engines down even more.


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## cadmobile500 (Feb 15, 2015)

thanks for everyone's input. the pulley came today. I will hopefully put it on tomorrow. hopefully well get some fresh snow soon. everything here is dry and crunchy.


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## 94EG8 (Feb 13, 2014)

You can't tell the difference between an 8hp and 10hp Tecumseh. I've swapped one for the other before on the same machine, you can't tell the difference, and to be totally honest with you I'm not sure there is one, I'll have to check some part numbers.


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## cadmobile500 (Feb 15, 2015)

they are not physically identical. 
the hmsk80 has a 3.125" bore and the hmsk100 has a 3.531" bore. other than that they are identical. same cam, crank and carb. 
this is why the hmsk100 makes an additional and 3ft/lbs of torque and does it 500rpm lower than the hmsk80. its limited by the cam...
were talking 20% more hp and torque. 
my question is, can you tell the difference? is it worth it?


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## RedOctobyr (Mar 2, 2014)

I went from a 24" Ariens with an HMSK80 (8hp L-head) to a 24" Ariens with an OHSK100, I think it is (10hp OHV). 

Both are 318cc, both are 3.125" bore. 

I think the 10hp one had a bit more power when I tried to do a head-to-head comparison last year, but it certainly wasn't an overwhelming difference. It wasn't an ideal comparison, deeper snow would have helped load them up more. 

As Shryp said, until you have enough of a load that one engine is at full-throttle, and is still slowing down, you won't see any difference. 

I sold the 8hp, so can't do any more comparisons. But reading some things about governor linkages got me wondering. The next time I take the carb-box cover off on the 10hp, I'm going to make sure the governor linkages are connected correctly. I might even try to double-check that the governor arm is adjusted properly on the shaft (when I bought this machine, something on the carb was connected wrong, so it's been messed with a bit). 

One challenge I've had with being certain that I'm out-of-power, vs a potential governor issue, is not having any feedback on the engine's throttle position. If the governor was not working right, your RPM may drop under a load, but the engine's not actually at full-throttle. 

I've wondered about trying to connect a string to the throttle plate, for testing purposes. When under a heavy load, and the RPM has sagged, give the string a little tug. If nothing happens, you're out of power. If the engine sounds different, then your governor didn't have the throttle open fully. 

Part of what got me thinking about this was clearing 8-10" of light snow recently. I wasn't even taking a full 24", but I still heard the engine slow a bit. It got me wondering if that's merely acceptable "sag" in the governor, or if I'm already power-limited. It didn't sound like when going into a big snowbank, so I'm thinking it was related to the governor. 

Presumably no mechanical governor is perfect at holding speed exactly as the load varies. My Generac generator manual tells you to set the governor so you get 62-63 Hz with no load. As you add a load, the RPM drops closer to 60 Hz (3600 RPM).


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## greatwhitebuffalo (Feb 11, 2014)

Shryp said:


> The other thing is the governors are controlled by springs. As the springs get older they get stretched out and loose tension which slows the engines down even more.


bingo give that man a cigar...standard procedure here on these very old machines is, cut one coil off the governor spring, and re-attach it to increase tension. or, move it to a hole that is farther away, increasing tension. or in very few cases, there is a screw you can adjust to increase governor spring tension. or finally if you can, replace it with a new one that is oem correct for the engine.

the interface with the operator controls is what wears out on these machines. i.e. the control handles, springs, cables. a weak spring makes the engine hunt up/down in rpm.
installing a new control plate with tight throttle stops and new governor spring, made a world of difference on my AMF Dynamark. it went from being a quirky machine, to rock solid powerful machine that holds steady rpm at idle, and wide open throttle.


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## greatwhitebuffalo (Feb 11, 2014)

cadmobile500 said:


> they are not physically identical.
> the hmsk80 has a 3.125" bore and the hmsk100 has a 3.531" bore. other than that they are identical. same cam, crank and carb.
> this is why the hmsk100 makes an additional and 3ft/lbs of torque and does it 500rpm lower than the hmsk80. its limited by the cam...
> were talking 20% more hp and torque.
> my question is, can you tell the difference? is it worth it?



that's the factory specs. if you clock up the rpm with the 
WOT rpm speed screw, the 10HP will drive through deeper, denser snow packs, and break it up better. at least mine does. the snow comes shooting out of the chute faster too.

ps hey Cadmobile, do you have a 500 CID caddy ? I could have bought a '70 Eldo for $500 but passed on it. kick myself to this day for hesitating. it was high CR 400HP engine w/Qjet. 550 ft. lb. torque.


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## nt40lanman (Dec 31, 2012)

I don't know if there's something about my 10HP Tec but I generally keep mine off WOT and it still BLASTS snow. Like the torque band is lower.


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## cadmobile500 (Feb 15, 2015)

I went to put the pulley on today and discovered I am desperately in need of new belts. there are two belts that drive the auger (a third drives the wheels from the cam)and with the idler engaged one of the impeller/auger belts still has slack in it. also, my pulley choice was a bad choice. I only gained about an 1/8" in PITCH diameter measuring the top of the belt in the grooves. the pulley itself was a 1/2" bigger but was made for a 3/8" belt...

new belts will most likely solve the throwing problem I have. I will probably stay with a stock pulley until I can figure it out.

on a positive note, the engine I repowered with came with a non-emissions carb. I didn't realize that until I dropped a washer in the belly pan and had to tip her over.


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## cadmobile500 (Feb 15, 2015)

greatwhitebuffalo,
I have owned quiet a few caddy 500's. the most recent were a 74' eldo and a 76' coupe deville. the one from the 74' eventually made it into an 81' cutlass bracket/street car. it was bored .080" over and stroked .100" making it 530ci. I had some 68'-73' heads(small chamber) ported with bigger valves, custom pistons and H-beam rods and a custom cam ground made. it ran [email protected] with a 1.8 second 60'. it would blaze the tires at ANY speed on the street just by dropping it into low2 and hitting the gas. she wasn't much of a looker but function before fasion has always been my motto.


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## DennisCA (Feb 5, 2019)

Sorry for resurrecting an old topic but it seemed suitable and I have such a small question anyway I don't see it worth it's own thread.

Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.


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## classiccat (Mar 1, 2014)

DennisCA said:


> Sorry for resurrecting an old topic but it seemed suitable and I have such a small question anyway I don't see it worth it's own thread.
> 
> Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.


That's an odd one; maybe a screw-up on the Toro website :icon_scratch:?

To be safe, use the engine model # and look up the parts lookups at many of the online vendors. (partstree, jacks small engines, etc.).


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## DennisCA (Feb 5, 2019)

Perhaps it is, elsewhere on the site it does say the motor for the blower is 8HP, the 80 vs 100 I assume refers the 10HP motor.


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## Homesteader (Jan 12, 2019)

Was your impeller mod pre or post 8hp swap?
I upgraded my Ariens St824 to a 10hp after I installed an impeller kit and noticed a significant performance increase when blowing wet heavy snow or snow o already blew. Could be happenstance but for the last two seasons of having the 10hp my machine’s chute hasn’t clogged. It often clogged with the 8hp


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## RedOctobyr (Mar 2, 2014)

DennisCA said:


> Sorry for resurrecting an old topic but it seemed suitable and I have such a small question anyway I don't see it worth it's own thread.
> 
> Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.


Usually, the HSMK80 was the 8hp, and HMSK100 was 10hp. With your 828 model #, I would have expected HSMK80. 

Checking a different serial # range on Toro's site could be interesting. Maybe they made a mistake, as classiccat said. 

Definitely check other sites, as he said, and worst case see what comes up when searching for your full engine model info. Like HMSK80 155316S (D) 3159D, or something along those lines.


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## DennisCA (Feb 5, 2019)

I forgot to check today before work, will have to see later, but I am wondering, is it that big a deal? If a carburetor is said to be compatible with an HMSK80 motor, won't it fit even if it's not exactly the same design. Aren't they all more or less the same carb? Maybe some are adjustable and some are set (like the one I got)

Also difficult to sort out all the china fakes, ebay is filled with them, though a carburetor for 15€ is pretty **** cheap... I will take it apart later today I think, put it in the ultrasonic cleaner. What I mainly need are new gaskets and o-rings.


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## SimplicitySolid22 (Nov 18, 2018)

Hmsk80=318.46CC


Hmsk100=357.63cc


Same stroke 2.532 but different bore...


3.125 

vs.

3.312


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## DennisCA (Feb 5, 2019)

You misread what I said, I did not say a part for an HMSK100 should fit an HMSK80, but that a part said to be compatible with an HMSK80 ought to fit an HMSK80, right? Even if it's not exactly identical to that particular year of manufacture.

EDIT: Or did I misunderstand you?


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## SimplicitySolid22 (Nov 18, 2018)

DennisCA said:


> You misread what I said, I did not say a part for an HMSK100 should fit an HMSK80, but that a part said to be compatible with an HMSK80 ought to fit an HMSK80, right? Even if it's not exactly identical to that particular year of manufacture.
> 
> EDIT: Or did I misunderstand you?



Gotcha.....I would think so. But every manufacturer of blower had different specs for their Tecumseh's.(especially shaft variations.) So your best bet it to grab motor numbers and search directly to that specific model just to be safe.


I would assume the carb is the same on most HMSK80's.....ya never know by year...


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## SimplicitySolid22 (Nov 18, 2018)

DennisCA said:


> Sorry for resurrecting an old topic but it seemed suitable and I have such a small question anyway I don't see it worth it's own thread.
> 
> Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.



Wait....If it is an 828....That means it should come with an 8 hp and bucket is 28 inches......so I would think HMSK80 is correct for your Toro!!!???


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## SimplicitySolid22 (Nov 18, 2018)

DennisCA said:


> Sorry for resurrecting an old topic but it seemed suitable and I have such a small question anyway I don't see it worth it's own thread.
> 
> Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.



Can you find the numbers off your HMSK80????


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## DennisCA (Feb 5, 2019)

Oh yeah, I got the number now (HMSK80-155724X) and I also contacted Toro to let them know their info on the site was wrong. I've ordered a spare carburetor and I have taken apart the current one and have put it in the ultrasonic cleaner. It was actually quite clean from the start, the main thing seems to be the gasket for the bowl, it's in super bad shape. I was gonna replace it with a 2" o-ring today, the original gasket is somewhat different in shape but I think a normal o-ring should work, also replacing the one on the plastic fuel nozzle. 

I wonder why these parts are plastic, not really a motor person but when I saw it my initial reaction was thinking I ought to turn a copy in steel or brass/bronze on the lathe, but I guess if it's lasted this long it works.



SimplicitySolid22 said:


> Wait....If it is an 828....That means it should come with an 8 hp and bucket is 28 inches......so I would think HMSK80 is correct for your Toro!!!???


Yes exactly, I believe the Toro site is in error and I have informed them of this as well.


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## DennisCA (Feb 5, 2019)

Ok I got it back together and was going to put back together, lost the governor link... making a new one from tig wire... Now something happened with the throttle lever, some spring got loose or broke so it doesn't move back and forth as it should... Sigh. 

And so far all the fasteners have been metric but now, trying to take off the throttle assembly so I can have a look at it, I ran into a 1/4" bolt head and I don't have any imperial sockets. But I was just told a bit holder for screw drivers should work as a 1/4 socket so I will check if that works, still think maybe it's time to invest in an imperial socket set some day. 

Weird though to have this mix of metric and imperial in the same machine.


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## HCBPH (Mar 8, 2011)

DennisCA said:


> Are HMSK80 and HMSK100 parts compatible? I am just wondering since I want a carb rebuild kit for my Toro 828. I entered my model number (38635, 24000x serial range) into the toro site and it says my blower should have the HMSK100 but it has the HMSK80 motor.


Most of the carb kits I've bought for the larger engines (both online and from a local shop) have listed for 7 hp through 10 hp Tecumseh's. At one point I had 3 or 4 kits on hand, same number on each and used one in a 7 hp and one in a 10 hp without issue. Both had the fully adjustable carb (both low and high speed jets) and in fact one time used parts from a 7 HP carb to fix a 10 hp. 


Other than things like choke linkage, I can't say I've seen a big difference between the carbs on the 2 engines.


Just some comments.

PS the comment on imperial vs metric bolts sounds like GM cars back when they were first converting to metric. Engine was imperial and the rest of the car was metric. Real pain to deal with but it was what it was.


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## DennisCA (Feb 5, 2019)

Well I got the throttle fixed and the replacement control linkage from TIG rod works fine. Put the thing back together and added new fuel (alkylate gas) and it started on the first try. I still haven't gotten the leakage to stop. I think it's the drain valve which I did not touch, or perhaps the gasket to the bowl nut that I also did not swap out. But it works at least and seems to work fine.


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## tadawson (Jan 3, 2018)

If this is an old brass shutoff valve, they use a single rubber O ring as a packing. If it is, you can try tightening down the packing nut behind the knob a bit, or if that fails, replace the O ring . . . 



The fibre gasket on the bottom of the bowl typically holds up, but never say never . . .


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## pilot1950 (Apr 12, 2019)

cadmobile500 said:


> I blew the engine in my mtd 10/24 snow blower last year. it originally had a hmsk100 but all I could find at the time was a hmsk80 to replace it with. the hmsk80 I bought blows away the hmsk100 that was originally on the blower but I also turned the governor on it up to 3600rpm. im assuming the hmsk100 was down on power since it had the original oil from 2003(blower was given to me) and seized. im wondering if it would be worth it to find another hmsk100. is there a noticeable difference in power? ive already installed an impeller kit and have a 1/2" larger engine pulley to spin the auger impeller faster on the way. the hmsk100 makes an additional 3ft/lbs of torque and is 40cc's bigger. opinions? I really want to throw some snow since my driveway is 5-6 cars wide and I can only throw in one direction. thanks in advance.


Gents, Would you mind clarifying impellor kit for me? I'll assume this is something to fill the gap between the impellor and housing. Or maybe not?? if so, it is commercially available or simply home made? Thanks.


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## Sid (Jan 31, 2014)

There are several threads on impeller mods. Basically it is bolting strips of rubber belting to two blades of the impeller, barely or almost touching the volute or body of the impeller housing. 
Sid


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## pilot1950 (Apr 12, 2019)

Thanks Sid. Now I do see them on Ebay. Should be easy enough to fabricate on my own.


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