# ST824 Tecumseh-to-Predator Engine Swap



## Russell Stephan (Feb 9, 2021)

A one-take video overview presentation of the effort:


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## Kiss4aFrog (Nov 3, 2013)

Welcome to SBF Russell









Thanks for the video


.


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## paulm12 (May 22, 2015)

Thanks for the video, well done, waiting to see your modified/new belt cover.


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## Russell Stephan (Feb 9, 2021)

paulm12 said:


> Thanks for the video, well done, waiting to see your modified/new belt cover.


The modifications on the OEM unit will get me through the season.


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## arienskids (Jan 26, 2018)

They make belt cover risers for an st1136 that will work for you


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## Oneacer (Jan 3, 2011)

@Russell,

You will surely want to fix that open cover ... You do not want water and snow in all the belts like you have it there.

Also, ditch the lawn turf tires, and get yourself some nice XTrac snow tires.


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## arienskids (Jan 26, 2018)

These are the ones I used


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## Russell Stephan (Feb 9, 2021)

> They make belt cover risers for an st1136 that will work for you


Good to know! I'll have to look into that.


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## Russell Stephan (Feb 9, 2021)

> You will surely want to fix that open cover ... You do not want water and snow in all
> the belts like you have it there.
> 
> Also, ditch the lawn turf tires, and get yourself some nice XTrac snow tires.


Per mention in the video, a cover replacement or modification will be forthcoming. But, for the time being, the modified original will suffice.

Central Ohio doesn't get the levels of snow to warrant a deep concern or additional expenditures for tire/traction issues. But, it's nice to know there are other options, thanks.


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## db130 (Feb 16, 2013)

Buy the complete kit for less: 
*Ariens 52422600*

Comes with the belt cover, the risers, and the hardware.


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## Russell Stephan (Feb 9, 2021)

And since it's a completely fresh engine, might as well add a tach/hour meter. No doubt, I'll probably end up putting on a stage one hop-up kit with a 4° advance woodruff key. Might be a good idea to know _exactly_ the engine RPMs.

And from the parts bin, a D handle for the pull-cord.


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## SharpAndCunning (Mar 1, 2019)

This is an awesome thread. I'm excited to see the difference between the stock Predator motor and the throwing distance upgrade with the hop up kit, if you choose to do it!


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## Russell Stephan (Feb 9, 2021)

We'll see. First, I have to guaranty all the currently-delivered PTO power makes it into thrown snow. Hitting big drifts doesn't bog the engine like I would expect. It does, however, cause snow to dribble out of the discharge chute. I have a feeling there's a bit of belt slippage going on. The unit does have wipers installed on two of the four impeller blades.

I've done some preliminary research on a possible double belt impeller drive. But, it looks like it will be a rather custom and intensive fabrication exercise. There does look to be some extra belt friction available with some simple modifications to the engagement clutch mechanism -- increasing the throw of the idler pulley into the belt slack. Or, a slightly larger PTO impeller pulley is also a possibility.

It might be better to keep this one as-is and wait for a roached engine chassis to come up on Craigslist or FB Marketplace which will accept the Ariens double impeller belt kit.

I'm already on the lookout for a parts chassis to obtain a chute drive ring for building a taller and straighter example.


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## ou2mame (Dec 23, 2019)

I'm patiently waiting for the predator 420cc engines to go on sale at harbor freight and then I'm going to be putting one on my st824. There's a lot of mods for these engines too which makes it fun. I definitely want to straight pipe it haha


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## Russell Stephan (Feb 9, 2021)

> I'm patiently waiting for the predator 420cc engines to go on sale
> at harbor freight and then I'm going to be putting one on my st824.


Pull up the owner's manual *.pdf off the Harbor Freight web site and get the 420cc base dimensions from the back of the manual. Keep in mind, the diagram is not to scale so go by the listed dimensions and measure... The 301cc 8HP engine barely fits on the flat part of the engine deck and the 420cc motor is a bit larger base-wise. In stock configuration, the 8HP Predator does cause some belt slippage when hitting drifts and such. The 420cc would be worse. 8HP is kinda the limit without redesigning the impeller belt drivetrain.

Hell, even a Predator 5HP motor properly massaged can get up there in HP -- via billet flywheel, rod, valve springs, etc. So, the same modifications on the 8HP will eclipse the stock-configured 420cc example.

Eventually someone is going to produce a super-charger for these Chinese screamers.


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## drmerdp (Feb 9, 2014)

Cool man, the 301 definitely feels more potent then the 318cc tecumsehs. I have one on my Simplicity 860. I used the stock pulley sheaves, but it can easily handle a bigger auger drive pulley.


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## Russell Stephan (Feb 9, 2021)

I've had the Predator engine on the ST824 for about a week and a half or maybe two... I did all the 20 minute break-in runs without the tach/hour meter installed. Well, after last night's snow storm blow-through and the day-long dig out of the neighborhood, I've got 6.1 hours of actual snow blowing on the hour meter... Granted I do about a dozen driveways when the thing is running in addition to a couple of miles of sidewalk passes.

But, some observations... In deep or dense stuff, the belt is slipping. We'll have to start playing with ways to firm up belt friction through a longer clutch pulley throw or larger diameter PTO wheel. Wipers on two of the four blades causes the ejected snow-stream to pulse. I will be adding wipers to the other blades to get ride of the unnecessary vibrations caused by the pulsing.

Other than those issues, the Predator engine absolutely sings. Once its bed-in time gets beyond 10 hours, I'll up the max throttle setting to 4,300 RPM or so.

FYI, the go-kart crowd does same-engine races with the small 5 HP Predator. They install the engines right out of the box and set the max RPM to 4,800 and race to test the drivers and not their hardware.


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## ChrisJ (Nov 27, 2014)

Im curious how a mod like a billet flywheel would have any effect of a continuous load application like a snowblower?

I also want to hear more about the 8hp.predators. Im on the fence between engines to replace my 8hp tec that's not strong enough for my use. I can get a 10 hp tec but I'm concerned it's also not enough and will still have the same annoyances of the 8hp tec (terrible carb etc ). But, it is a drop in replacement.

To me the carb and governor on the hondas and clones seem much better than the tec. Will the 8hp predator be that much stronger than an 8 hp tec that's in good shape?

The belts concerned me as well. Im also using an 824.


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## Russell Stephan (Feb 9, 2021)

> Im curious how a mod like a billet flywheel would have any effect
> of a continuous load application like a snowblower?


A billet flywheel because the OEM cast one may and has disintegrated under higher RPMs of modified engines.



> I also want to hear more about the 8hp.predators. Im on the fence
> between engines to replace my 8hp tec that's not strong enough for
> my use. I can get a 10 hp tec but I'm concerned it's also not enough
> and will still have the same annoyances of the 8hp tec (terrible carb etc ).
> But, it is a drop in replacement.


The 8HP Predator modified ST824 suffers zero engine power issues. The engine hardly changes RPMs at all. But, there is a lot of belt slipping when large quantities of snow or wet/heavy stuff are tackled.

The stock Predator is just fine until I come up with a way to reduce significantly the impeller belt slippage.



> To me the carb and governor on the hondas and clones seem much better
> than the tec. Will the 8hp predator be that much stronger than an 8 hp tec
> that's in good shape?


From my experience, the Predator engine is far smoother, quieter, and just sounds so much more well put-together. In a little more than nine days I've put 7.9 hours of actual snow blowing on the machine. I'm very satisfied.




> The belts concerned me as well. Im also using an 824.


As mentioned above, the belt is the current limiting factor in getting all that engine power into thrown snow.


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## Russell Stephan (Feb 9, 2021)

Interesting... Stumbled on this electro-magnetic clutch while what-iffing the belt slippage problem:






Xtreme Outdoor Power Equipment Clutches


We are the high performance PTO clutch leader with over 2,400 models ready to ship.




xtremeope.com


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> A billet flywheel because the OEM cast one may and has disintegrated under higher RPMs of modified engines.
> 
> 
> The 8HP Predator modified ST824 suffers zero engine power issues. The engine hardly changes RPMs at all. But, there is a lot of belt slipping when large quantities of snow or wet/heavy stuff are tackled.
> ...



Are you completely sure your belts didn't get wet?
Are those belts raw edge? From what I read last week raw edge belts grab better and can transfer more power. The original belts were raw.


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## Russell Stephan (Feb 9, 2021)

Then, I wondered if anyone has put a charger and/or electric start on the Predator 301cc engine:






That's all I need... Another big time/money sink project.


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## Russell Stephan (Feb 9, 2021)

> Are you completely sure your belts didn't get wet?


Can't say for 100% sure. But, the slippage is pretty constant and predictable when hitting bigger snow bites or heavy street plow cast-off.




> Are those belts raw edge? From what I read last week raw edge belts
> grab better and can transfer more power. The original belts were raw.


Doubtful. I just sourced the larger size needed for the engine swap from the local NAPA. Looks like I'm a gonna have to source a raw edge example.

Thanks for the pointer!


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> Can't say for 100% sure. But, the slippage is pretty constant and predictable when hitting bigger snow bites or heavy street plow cast-off.
> 
> 
> 
> ...



I'll help anyway I can.
Im tempted to put the hmsk100 on it because it's stronger but like I said before it'll still have the same crummy carb etc. I've been around many hmsk engines and they all run the same (not quite right).

The belts aside, your impression is the 8hp predator is noticeably stronger than the 8hp tecumseh was? I assume the tecumseh was in good shape?

Just trying to get a good comparison.


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## Russell Stephan (Feb 9, 2021)

> The belts aside, your impression is the 8hp predator is noticeably stronger
> than the 8hp tecumseh was? I assume the tecumseh was in good shape?


Yes. The Predator should also take to running a bit faster in stock configuration better than the OEM Tecumseh. And hop-up parts are easily obtained for the Predator series. 

Raw edged belt ordered. Although, it won't get here until March...


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## ou2mame (Dec 23, 2019)

Russell Stephan said:


> Pull up the owner's manual *.pdf off the Harbor Freight web site and get the 420cc base dimensions from the back of the manual. Keep in mind, the diagram is not to scale so go by the listed dimensions and measure... The 301cc 8HP engine barely fits on the flat part of the engine deck and the 420cc motor is a bit larger base-wise. In stock configuration, the 8HP Predator does cause some belt slippage when hitting drifts and such. The 420cc would be worse. 8HP is kinda the limit without redesigning the impeller belt drivetrain.
> 
> Hell, even a Predator 5HP motor properly massaged can get up there in HP -- via billet flywheel, rod, valve springs, etc. So, the same modifications on the 8HP will eclipse the stock-configured 420cc example.
> 
> Eventually someone is going to produce a super-charger for these Chinese screamers.


I've seen a couple people wedge a 420cc onto an st824... I think the bolts will fit but the engine will hang off. I'm OK with that haha.. And whats the deal with the belts slippage? Isn't that a tension related issue and not an engine related issue?


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## ChrisJ (Nov 27, 2014)

ou2mame said:


> I've seen a couple people wedge a 420cc onto an st824... I think the bolts will fit but the engine will hang off. I'm OK with that haha.. And whats the deal with the belts slippage? Isn't that a tension related issue and not an engine related issue?


Tension sure, but a certain size belt is only going to handle a certain amount of power.

Do you have any pictures of the 420cc on an 824 machine? It sure would be nice to have the charging system etc that comes with the bigger engine.


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## ou2mame (Dec 23, 2019)

ChrisJ said:


> Tension sure, but a certain size belt is only going to handle a certain amount of power.
> 
> Do you have any pictures of the 420cc on an 824 machine? It sure would be nice to have the charging system etc that comes with the bigger engine.


I made this post asking about doing a 420cc swap. I'm waiting for it to go on sale at harbor freight.








Looking to repower Ariens ST824


So my order for an LCT 414cc fell through and now I'm back to square one looking for a motor. I use the snowblower as a lawn mower as well in the summer so I'm looking for a motor that I can easily take the air filter off and put it back on. I'm looking at the Predator 420cc now as a viable...




www.snowblowerforum.com





Here's a picture someone posted of the bolt spacing in that thread for a honda engine with the same bolt pattern. The bolts are on the edge, but they should fit.


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## Russell Stephan (Feb 9, 2021)

As stated previously, the 420cc footprint is slightly larger. When installing the 301cc engine I did have to grind angles on the bolt head hex flats to avoid interference with the 45° bend in the engine deck at the edge allowing the studs to stand straight. If someone has done it previously, then obviously, it can be done.

As for getting all that power transmitted into throwing snow, Ariens did have issues with their greater-than 9HP setups necessitating the double-belt upgrade kits. No such kit exists for the ST824. So, we're on our own engineering wise unless someone has documented a fix. Power that can't be transmitted is the same as no additional available power.

There's only one way to test whether or not all that power is making its way into throwing snow. Stuff the nose of the blower into a big heavy pile of fresh street plow cast-off and see if it stalls the engine. If the engine doesn't stall when overloaded, the choices are: The belt is slipping. The impeller design is too small. The test isn't inputting enough heavy snow.

Also, see previous post concerning a YouTube presentation on installing charging coils and an electric starter on the 301cc engine.


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> As stated previously, the 420cc footprint is slightly larger. When installing the 301cc engine I did have to grind angles on the bolt head hex flats to avoid interference with the 45° bend in the engine deck at the edge allowing the studs to stand straight. If someone has done it previously, then obviously, it can be done.
> 
> As for getting all that power transmitted into throwing snow, Ariens did have issues with their greater-than 9HP setups necessitating the double-belt upgrade kits. No such kit exists for the ST824. So, we're on our own engineering wise unless someone has documented a fix. *Power that can't be transmitted is the same as no additional available power.*
> 
> ...


Agreed.
There is a benefit to using a stronger engine than the belts can handle. It could be run a lower rpm which would both be easier on the ears, and the engine.

A 3.5" pulley which I would expect should grab better than a 2.75 would give 1100 rpm impeller speeds at 2800 rpm and it would also give 1400 rpm at 3600 rpm if the need is there. Unless of course that single belt just can't do it.


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## Russell Stephan (Feb 9, 2021)

> Agreed.
> 
> There is a benefit to using a stronger engine than the belts can handle.
> It could be run a lower rpm which would both be easier on the ears, and
> the engine.


Design and engineering are always a, "Pick your poison," proposition of trade-offs...


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## drmerdp (Feb 9, 2014)

In the performance world we have a saying. 

Fast, cheap, reliable. Pick 2.


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## drmerdp (Feb 9, 2014)

@Russell Stephan So I’ve been dealing with some belt slippage on my snapper 1030. The engine is plenty healthy and torquey and the impeller gearing is quite low. But in heavy snow throwing distances suffer even with impeller seals. 

My though is why does my Honda with a big motor and high impeller speeds have ZERO slippage. It might have something to do with the large drive pulleys having greater surface area or maybe Honda uses better belts or BOTH.

Honda uses a bando w800 belt for the auger system. It certainly works great, but there is one higher line of belt the w1000. Once you dial in the most appropriate belt length, maybe try a w800 or w1000 belt of the correct size and see how it performs.



https://www.bandousa.com/media/uploads/0/194_BUI-1066_Premium-Ag-Belts-flier.pdf


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## ChrisJ (Nov 27, 2014)

drmerdp said:


> @Russell Stephan So I’ve been dealing with some belt slippage on my snapper 1030. The engine is plenty healthy and torquey and the impeller gearing is quite low. But in heavy snow throwing distances suffer even with impeller seals.
> 
> My though is why does my Honda with a big motor and high impeller speeds have ZERO slippage. It might have something to do with the large drive pulleys having greater surface area or maybe Honda uses better belts or BOTH.
> 
> ...



Maybe I'm seeing wrong but it also seems like hondas have weaker smaller engines than other brands. Do they handle wet snow better as well or only dry stuff?


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## drmerdp (Feb 9, 2014)

ChrisJ said:


> Maybe I'm seeing wrong but it also seems like hondas have weaker smaller engines than other brands. Do they handle wet snow better as well or only dry stuff?


Weaker, No. 

Smaller, in comparison to the most recent offerings from the Chonda world yeah they generally have smaller displacements. They also have hydrostatic transmissions so displacement is not a non issue. 

In regards to wet snow. It was the first chute design using a collar at the base to eliminate snow spray that effected wet snow performance in HSS machines.


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## ChrisJ (Nov 27, 2014)

Well.
I had a brilliant idea for a few minutes of converting the impeller/auger to a chain drive with an adjustable clutch to limit torque.

Then I realized there would be no way to stop it under normal conditions.


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## Russell Stephan (Feb 9, 2021)

> I had a brilliant idea for a few minutes of converting the impeller/auger
> to a chain drive with an adjustable clutch to limit torque.


Have a gander earlier in the thread where I link to a YouTube video about installing a charging coil and starter on a 301cc Predator engine... Just before that I provide a link to a electro-mechanical clutch used in commercial lawn mowers.

Although, I would doubt charging coils would be enough to lock up the clutch. But an alternator... ;-)


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## ChrisJ (Nov 27, 2014)

For what it's worth I noticed there's also a Predator 5500W generator that uses the 301 engine.
The general rule is 2HP per KW and the Tecumseh 10HP was used on some 5000W generators. Also, from what I've found the Tecumseh HM100/HMSK100 was rated something like 15.5ftlb @ 2600 while the Predator 301 is rated 14.9ftlb but they didn't specify an RPM but I would assume 2500RPM.

Very strange that a Harbor Freight engine would perform better than the claims. Isn't it? 

Meanwhile we've got shop vacuums that claim to be 6HP when they're lucky to be a sixth of that.


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## Preacherman (Dec 20, 2020)

Interesting info I’m a follower. 
Mounting a larger motor isn’t the hard part- a simple motor mount plate would solve that issue. You could either weld the plate or bolt it to the tractor. It seems that most of the issue is finding a belt the proper size. I do remember a thread on here that the belt was 1/2” too long why not just mount the motor 1/2” higher then finding a belt isn’t the issue. I get the belt guard will need modified, but that too isn’t a very hard thing to do.


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## ou2mame (Dec 23, 2019)

Preacherman said:


> Interesting info I’m a follower.
> Mounting a larger motor isn’t the hard part- a simple motor mount plate would solve that issue. You could either weld the plate or bolt it to the tractor. It seems that most of the issue is finding a belt the proper size. I do remember a thread on here that the belt was 1/2” too long why not just mount the motor 1/2” higher then finding a belt isn’t the issue. I get the belt guard will need modified, but that too isn’t a very hard thing to do.


They sell a riser kit for the belt guard so that isn't an issue.


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## Russell Stephan (Feb 9, 2021)

For those attempting to fine-tune belt lengths for the absolute minimum amount of slippage, McMaster-Carr offers custom-lengthed belt building:

McMaster-Carr


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> For those attempting to fine-tune belt lengths for the absolute minimum amount of slippage, McMaster-Carr offers custom-lengthed belt building:
> 
> McMaster-Carr


But still no raw edge selection, no?

Can an idler on the opposite side be used to take up some slack?


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## Russell Stephan (Feb 9, 2021)

> But still no raw edge selection, no?
> 
> Can an idler on the opposite side be used to take up some slack?


My standard lengthed raw-edge belt should be arriving today or tomorrow. Although, it does look like our weather has moved out of the standard winter pattern. The snow may be over until next year...

My plan of attack for tightening up the drive system involve:

1) Attempting to "push in" the reach of the idler pulley when engaged. I should be able to gain 1/4" with a minimum of fabrication/modification.

2) After #1 is completed, bump up the spring tension in the idler mechanical circuit with a stiffer spring.

3) Try a slightly larger diameter idler pulley.

------

And if those don't work out, upgrade to a slightly larger diameter 5L belt width impeller pulley and driven wheel.


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> My standard lengthed raw-edge belt should be arriving today or tomorrow. Although, it does look like our weather has moved out of the standard winter pattern. The snow may be over until next year...
> 
> My plan of attack for tightening up the drive system involve:
> 
> ...



Do you recall what size the idler is?
I'm guessing 1.75 - 2"?

Odd question.....but I have a reason for asking.


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## Russell Stephan (Feb 9, 2021)

> Do you recall what size the idler is?
> I'm guessing 1.75 - 2"?
> 
> Odd question.....but I have a reason for asking.


It's a 2" diameter with a 3/4" running channel width.


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## Russell Stephan (Feb 9, 2021)

And, the education continues...

My raw-edge belt has arrived. I have yet to install it. It looks like our snow season is over for 2021. But, my research on V-belts has not let up.

From all I've read, the typical 4l and 5l belts are fractional HP belts for extremely light-duty applications under or around 1HP. Hmmmmm. An eight HP engine throwing snow? The belt certainly has to be rated for more than a fraction of 1HP. It seems there are light-duty belts (2L, 3L, 4L, 5L). Then, there are the conventional higher HP-rated belts of A, B, C, D, and E designations. And a third category called "narrow" or "wedge" belts which have greater side surface area for more power transmission capabilities.

Here is an informative chart with recommended HP ratings for various belt designations:



https://www.bestorq.com/Library/TechInfo/techinfo/V-Belt%20Quick%20Selection%20Guide.pdf



So, how to proceed? I've done a bit of research and can't seem to find a cross-reference guide which explicitly states the type of belt the OEMs use. I'm guessing, however, it's most likely the "narrow" or "wedge" belts. It's the only type which appears to match up with eyeballed width and depth guesses on my part along with the engine's HP rating. However, I hate guessing...

Given the various types of belt profiles and such, I figured there had to be a set of gauges for determining _exactly_ what type of belt is used in a given sheave/pulley. And yes! There are gauges. So, to avoid guessing, I ordered a set off eBay. The gauges will come in handy for other belt applications in the shop too, like the air compressor which recently decided to eat a 4l linked belt after more than a decade.

Now we wait on the arrival of the gauge set in hopes of coming up with the proper belt to get all that engine power into throwing snow.


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## ChrisJ (Nov 27, 2014)

Yes they're rated as fractional belts but I believe that's under continuous use. It doesn't mean it can only handle that much without breaking etc.

I believe my dad's tractor used a 5L for 12hp.
But, the pulleys were larger than 2.75" and it had a much stronger spring on the idler.

Im having issues too because it appears choosing belts isn't simple at all.

On a similar subject. It looks like the Predator 301 and 420 are almost identical as far as shaft hight.


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## JLawrence08648 (Jan 15, 2017)

Russell, you are reading too much in to this. For a drive belt, they generally are 3L, auger belts generally are 4L. My preferred belts are D&D Power, Pix, A.I. Sports, for their durability and their accurate length.


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## Russell Stephan (Feb 9, 2021)

> Russell, you are reading too much in to this.


If that were indeed the only issue...

As mentioned numerous times throughout the whole thread and repeated again here, the ST824 with the Predator engine suffers from belt slippage. Hitting deep snow does not bog the engine down. Rather, it just brings the thrown snow to a dribble.

I'm in the process of attempting to get all that engine power into thrown snow.


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## ChrisJ (Nov 27, 2014)

Especially considering the 8hp predator appears to be stronger than an 8hp tecumseh.


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> If that were indeed the only issue...
> 
> As mentioned numerous times throughout the whole thread and repeated again here, the ST824 with the Predator engine suffers from belt slippage. Hitting deep snow does not bog the engine down. Rather, it just brings the thrown snow to a dribble.
> 
> I'm in the process of attempting to get all that engine power into thrown snow.


You kept the stock pulley sizes right?
How much bigger one an impeller pulley do you think it would need to make the new belt the correct length?


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## Russell Stephan (Feb 9, 2021)

> You kept the stock pulley sizes right?
> 
> How much bigger one an impeller pulley do you think it would need to
> make the new belt the correct length?


The current drive and driven pulleys/sheaves are stock. The current 4L belt (420) is as close to perfect in terms of length that can be applied without going off into the weeds of quarters or eighths of inches. The only reason I mentioned a drive pulley diameter increase is because this is an easy way to gain sheave/belt surface area contact.

Tinkering with the belt/sheave setup will be on-hold until the belt profile gauges show up so as to remove any and all doubt concerning the absolute correct application.


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> The current drive and driven pulleys/sheaves are stock. The current 4L belt (420) is as close to perfect in terms of length that can be applied without going off into the weeds of quarters or eighths of inches. The only reason I mentioned a drive pulley diameter increase is because this is an easy way to gain sheave/belt surface area contact.
> 
> Tinkering with the belt/sheave setup will be on-hold until the belt profile gauges show up so as to remove any and all doubt concerning the absolute correct application.



The reason I'm asking is I'm still feeling out how difficult the 13HP / 420 would be to get to work decently. I believe the 301 and 420's shaft height is almost identical.
I recall you buying a belt that seemed too long unless that's what you ended up with?

I had planned on making a new sheath from scratch that could use a 5L belt for the impeller, so any size is possible within reason. With the 13Hp i'd want something closer to 3" or 3.25" though to get the speed up some. But literally anything in between is possible. If I go through with it I'd like it to run stock impeller speeds at around 3000- 3300 rpm.


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## Russell Stephan (Feb 9, 2021)

> The reason I'm asking is I'm still feeling out how difficult the 13HP / 420 would be
> to get to work decently. I believe the 301 and 420's shaft height is almost identical.
> I recall you buying a belt that seemed too long unless that's what you ended up with?


See the YouTube video description of the post starting this whole thread concerning the trials and tribulations with belt lengths.



> I had planned on making a new sheath from scratch that could use a 5L belt for the
> impeller, so any size is possible within reason. With the 13Hp i'd want something
> closer to 3" or 3.25" though to get the speed up some. But literally anything in
> between is possible. If I go through with it I'd like it to run stock impeller speeds at
> around 3000- 3300 rpm.


A custom sheave setup certainly opens a world of possibilities. I did find a couple of machine shops on-line that specialize in making custom sheaves. I really do need a fully-equipped industrial-sized fabrication shop available for my personal use!

If I were going with a custom belt/sheave modification, I'd skip the fractional horsepower belt profiles and go directly to the industrial grades I mentioned a few recent posts ago.

Be sure to check if the Ariens dual pulley upgrade kit would possibly work for your setup, though.


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## ChrisJ (Nov 27, 2014)

Russell Stephan said:


> See the YouTube video description of the post starting this whole thread concerning the trials and tribulations with belt lengths.
> 
> 
> A custom sheave setup certainly opens a world of possibilities. I did find a couple of machine shops on-line that specialize in making custom sheaves. *I really do need a fully-equipped industrial-sized fabrication shop available for my personal use!*
> ...



It is nice but the problem I always have is never enough time.
I'm currently modeling new hinges for my antique refrigerators so I can machine new ones but again, never enough time to finish.

The reason I was thinking a 5L belt is it seemed typical to use such for these applications. I had a very hard time figuring out minimum pulley diameter for belts as well as which allowed a back idler. It's certainly far from my area of expertise.


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## Russell Stephan (Feb 9, 2021)

I took the gas tank off the old blown Tecumseh engine today. Nice little crack in the block...


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## nwcove (Mar 2, 2015)

Russell Stephan said:


> I took the gas tank off the old blown Tecumseh engine today. Nice little crack in the block...
> View attachment 177401


That’ll buff right out.


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## Russell Stephan (Feb 9, 2021)

> That’ll buff right out.


After a bunch of TIG work and/or aluminum brazing rod... But, with the time/money curve, a whole new engine for the win! ;-)


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## Russell Stephan (Feb 9, 2021)

The roached 8HP Tecumseh internals.

The galled crank connecting rod journal. What's left of the piston connecting rod. The engine case from the inside with a yellow trouble light revealing the big crack.


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## Russell Stephan (Feb 9, 2021)

I've got the engine fully disassembled. If there's any parts required, give me a shout!

Magneto, muffler, engine side cover, head, flywheel with starter gearing, cam, pull cord mechanism and shroud.


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## snow blows (Jan 9, 2016)

Would a small shim or plate under the motor work? Might work if there is a little play or adjustment on the drive belt?


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## Dusty (Dec 13, 2018)

I would have just thrown a Predator 212 on, its a direct bolt on without modifications and is already far more powerful than the original 8hp Tecumseh and 10hp for that matter. I'm running one on my 1971 32" wide Predator and that things a beast. I just picked up that ST824 last week and if I keep it, that's probably exactly what I'm gonna do drop a 212 on it and retire my 24" from 1971 keep the 87 ST824 znd the 71, 32". Being a 24" its all it really needs, the 32" has plenty of power as well, but thats the one that could really use the jump if any.


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## Dusty (Dec 13, 2018)

Russell Stephan said:


> Per mention in the video, a cover replacement or modification will be forthcoming. But, for the time being, the modified original will suffice.
> 
> Central Ohio doesn't get the levels of snow to warrant a deep concern or additional expenditures for tire/traction issues. But, it's nice to know there are other options, thanks.


Chains on those turf tires still beat out any tire, thats what I did to mine, it barrels thru just about anything no problem, my ST824 has the Snohogs, I'll probably just throw a set of chains over those too. They worked great together on my old Snapper that had Snohogs.


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## Dusty (Dec 13, 2018)

ou2mame said:


> I'm patiently waiting for the predator 420cc engines to go on sale at harbor freight and then I'm going to be putting one on my st824. There's a lot of mods for these engines too which makes it fun. I definitely want to straight pipe it haha


My buddy put a 420 on his. Its too big and heavy and it keeps burning out belts. It tires him out fast and is a bear to operate. The 301 is more than ample, honestly the 212 on a 24" is already far more powerful than the 8hp Tecumseh ever was and that one is the direct bolt on replacement to the Tecumseh.


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## Dusty (Dec 13, 2018)

Russell Stephan said:


> Pull up the owner's manual *.pdf off the Harbor Freight web site and get the 420cc base dimensions from the back of the manual. Keep in mind, the diagram is not to scale so go by the listed dimensions and measure... The 301cc 8HP engine barely fits on the flat part of the engine deck and the 420cc motor is a bit larger base-wise. In stock configuration, the 8HP Predator does cause some belt slippage when hitting drifts and such. The 420cc would be worse. 8HP is kinda the limit without redesigning the impeller belt drivetrain.
> 
> Hell, even a Predator 5HP motor properly massaged can get up there in HP -- via billet flywheel, rod, valve springs, etc. So, the same modifications on the 8HP will eclipse the stock-configured 420cc example.
> 
> Eventually someone is going to produce a super-charger for these Chinese screamers.


The 212 is 6.5 to 7hp, here judge for yourself on this 32 wide, engine is stock.


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## ChrisJ (Nov 27, 2014)

Dusty said:


> The 212 is 6.5 to 7hp, here judge for yourself on this 32 wide, engine is stock.


Judging by what I've found, the 212 is likely 6.5 to 7HP but it's not quite as strong as a Tec HMSK80 and far from the HMSK100 (10HP).
The 301 however, is very close to the HMSK100 and quite a bit stronger than the HMSK80.

Your video shows the 212 doing very well with some nice light fluffy snow. I'm curious how it handles very wet packed snow.
It's looking like the bearing on my impeller shaft has seen better days, so I've got a feeling that's been taking some of my power. But the wet packed snow I deal with kills my HMSK80.


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## Russell Stephan (Feb 9, 2021)

> Would a small shim or plate under the motor work? Might work if
> there is a little play or adjustment on the drive belt?


This is certainly a solution for fine-tuning the PTO height.

However, simple washers used as spacers between the engine deck and the motor would be far cheaper in addition to allowing fine-fine tuning.

Thanks for the suggestion!


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## Dusty (Dec 13, 2018)

ChrisJ said:


> Judging by what I've found, the 212 is likely 6.5 to 7HP but it's not quite as strong as a Tec HMSK80 and far from the HMSK100 (10HP).
> The 301 however, is very close to the HMSK100 and quite a bit stronger than the HMSK80.
> 
> Your video shows the 212 doing very well with some nice light fluffy snow. I'm curious how it handles very wet packed snow.
> It's looking like the bearing on my impeller shaft has seen better days, so I've got a feeling that's been taking some of my power. But the wet packed snow I deal with kills my HMSK80.


That snow while not as high wasn't light and fluffy it was wet, heavy snow, heres the video my 71, 24" with the Predator 212, in 15 to 18 inches, dense heavy snow. The 32" reacts the same way, just larger swaths in this stuff too, this is where the 32" could borderline use a 301" but not really, it still has far more, grunt, power, pickup and throwing capability than the Tecumseh HMSK80 and 100 and since no altering is required it makes it a quick easy changeover. For a 24" wide unit the 212 has beyond enough power, but again even on the 32" it handles it well, the 32 was their as well behind out of frame.
I posted a thread last night with both videos and about a month ago I posted a thread on the commercial abuse these machines and those engines are taking and how they handle. I said it than and I'll say it here the 212 does awesome and its a direct bolt in swap. Only on certain machines like my 71"s the chute rod had to be altered for the OHV, but everything else stayed exactly the same. On the newer ST824 no modifying is required, just remove the old motor and add the 212 and done and you'll have far more power than you ever did with the old Tecumseh.
The Predator 212 is more than ample for these units, their also far lighter than the 301 and 420 which is huge. These don't tire us out, the units are easy to maneuver while clobbering that snow. These videos help prove that.


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## ChrisJ (Nov 27, 2014)

Dusty said:


> That snow while not as high wasn't light and fluffy it was wet, heavy snow, heres the video my 71, 24" with the Predator 212, in 15 to 18 inches, dense heavy snow. The 32" reacts the same way, just larger swaths in this stuff too, this is where the 32" could borderline use a 301" but not really, it still has far more, grunt, power, pickup and throwing capability than the Tecumseh HMSK80 and 100 and since no altering is required it makes it a quick easy changeover. For a 24" wide unit the 212 has beyond enough power, but again even on the 32" it handles it well, the 32 was their as well behind out of frame.
> I posted a thread last night with both videos and about a month ago I posted a thread on the commercial abuse these machines and those engines are taking and how they handle. I said it than and I'll say it here the 212 does awesome and its a direct bolt in swap. Only on certain machines like my 71"s the chute rod had to be altered for the OHV, but everything else stayed exactly the same. On the newer ST824 no modifying is required, just remove the old motor and add the 212 and done and you'll have far more power than you ever did with the old Tecumseh.
> The Predator 212 is more than ample for these units, their also far lighter than the 301 and 420 which is huge. These don't tire us out, the units are easy to maneuver while clobbering that snow. These videos help prove that.



Interesting.
The machine is certainly making it look light that's for sure.


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## Dusty (Dec 13, 2018)

ChrisJ said:


> Interesting.
> The machine is certainly making it look light that's for sure.


Have you watched thecsecond video, going thru 15 inches of snow yet? I sent it.


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## Husqvarna_10530SBE (Oct 9, 2015)

That snow is not nearly as wet and heavy compared to the stuff I get near the coast.

That machine does a decent job with the 212, though.

I'm thinking I would need a 301cc or larger engine on my 30" Husqvarna that currently has a HMSK100. But, I am thinking of changing the impeller drive pulley from 2.75" to 3". If that gets me 10-15' more throwing distance, then no need to upgrade the engine.

BTW, when Husqvarna changed over from Tecumseh engines to LCT they started using an engine mounting plate for the larger engines. That would work for me because the chassis already has the holes on the sides to bolt the engine plate in the correct location.

PartsTree - Home of OEM Parts for Outdoor Power Equipment


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## Husqvarna_10530SBE (Oct 9, 2015)

Preacherman said:


> Interesting info I’m a follower.
> Mounting a larger motor isn’t the hard part- a simple motor mount plate would solve that issue. You could either weld the plate or bolt it to the tractor. It seems that most of the issue is finding a belt the proper size. I do remember a thread on here that the belt was 1/2” too long why not just mount the motor 1/2” higher then finding a belt isn’t the issue. I get the belt guard will need modified, but that too isn’t a very hard thing to do.


Correct me if I'm wrong, but if the belt is 1/2" long, wouldn't you only need to raise the engine a 1/4"?


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## Russell Stephan (Feb 9, 2021)

A long overdue update... The use of an AX40 V-belt for the impeller seems to have banished the belt slipping when the nose of the machine is stuffed into a pile of end-of-driveway city plow cast-off.

At the start of the 2022 season, the hour meter on the Predator 301cc engine married to the ST824 chassis reads 23.2 hours.


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## Russell Stephan (Feb 9, 2021)

> Thanks for the video, well done, waiting to see your modified/new belt cover.


See the current "Short & Stubby" thread. I fabbed up a make-do cover recently in that thread.


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