“Anything worth doing is worth doing to excess.”
Edwin Land
Snowblower impeller kit….great success!
- Thread starter RhondaHonda
- Start date
Edwin Land
Where did you find this info?@Ranger83 I will partially agree with you on the Honda's and that their overall design tends to throw snow further. But that Ariens 28" Pro with the 420cc engine is about as good as it gets!
Nerd alert....
Impeller tip speed is driven by two factors, the impeller diameter and the impeller pulley diameter to engine pulley diameter ratio. The larger impellers found on the commercial units can spin at a slower RPM and still have a high tip speed. Generally speaking for the best snow throwing performance you want a larger impeller but this requires more engine to handle the increases leverage of the larger impeller.
According to most internet expertsthe ideal impeller tip speed is around 50mph. You reach the point of diminishing returns after this. A common impeller speed is 1100-1300RPM depending on the machines design. 1300-1400RPM is about as fast as you want to spin it. And FYI, the larger machines often use a double v-belt pulley for the impeller so the belts don't slip at high loads.
The Honda HSS1332AT, the big 32" commercial one has an impeller diameter of 13.5", a tip speed of 51.6mph and an impeller speed of about 1380RPM. The snowblower forums call this one of the best snowblower out there. $4,000 and has their GX390cc engine. The largest engine Honda makes in this class. Honda uses sealed roller bearings on the shafts where most others use bushings. Their clearances are also very tight as well so they give you every bit of performance the machine has to offer.
The Ariens Professional 926 series with the 420cc engine has an impeller diameter of 14", a tip speed of 46mph and an impeller speed of 1100RPM.
My older Murray with the 8.5HP (318cc) Tecumseh Snow King has a 12" impeller, a tip speed of 42.8mph and an impeller speed of 1200RPM. Because it is a 12" impeller it is already spinning kind of fast to throw the snow. That is max engine speed. My engine loses RPM at high loads and that impeller tip speed becomes 30mph with an impeller speed of 850RPM. Not ideal and is the main reason it barfs the heavy snow rather than throws it.
If I were to install a larger engine capable of handling the extra load and were to install a smaller impeller pulley (7.75" vs current 9") the tip speed would increase to 49.7mph with an impeller speed of 1390RPM. That is about as fast as I'd want to spin the impeller and is on par with the impeller speed of the Honda.
What about the big Oshkosh machines? They throw over 100 feet. This model has a 450hp drive motor and a 515hp blower motor.
@Ranger83 I always wondered what would happen if those super duper snow machines sucked up a tire/wheel discarded on the side of the highway...
But for all that impeller speed/tip speed stuff, believe it of not BITOG is not the only obscessed forum out on the internet. As crazy as we are here for oil, there is the equivelent forum of nuts for whatever topic. Snowblower forums are just as busy as we are here. That is where I got most of my information.
For the RPM's, MPH's and such I look at the parts catalogs to find the diameters of the pulleys and impellers. Then it is some simple math.
But for all that impeller speed/tip speed stuff, believe it of not BITOG is not the only obscessed forum out on the internet. As crazy as we are here for oil, there is the equivelent forum of nuts for whatever topic. Snowblower forums are just as busy as we are here. That is where I got most of my information.
For the RPM's, MPH's and such I look at the parts catalogs to find the diameters of the pulleys and impellers. Then it is some simple math.
The gearbox doesn't drive the impeller blower
Good luck repairing your Tecumseh Snow King. I find them to be very sound engines and if on the right machine with an impellar kit they rock. Parts are still well supported. There are a million of them still out there. They put out good torque and you do not have to rev them over 3500RPM to get good performance. With the Asian OHV engines, people (myself included) have turned them upto 3800-3900RPM and they do well there. Why beat on the engine if you do not need to. The exhaust valves on the Tec Snow kings are notorious for getting too tight. That may be one of your issues. After I do a valve lash adjustment and clean up the carbon around the upper end of the engine, and install a new head gasket, they perform like new again. Also, if you have the test equipment do a leak down test to get an idea of the engines overall tightness. If you decide to do a valve lash adjustment, you will pull the head,you can inspect the cyl wall and decide if you need to do the rings. Good Luck and let us know how you made out. I am sure you know this, But for the readers I will add. If you have a two shaft Tecumseh Snow King engine, doing a repower is very tricky and involved if going to a one shaft engine. Like a Preditor. Ask me how I know. Also, your Murray snow blower has a rectangular opening from the bucket to the chute. That seems like a bad design and they are well known for clogging. I am sure the engineers had some rational for doing that but they do not perform well on wet snow. The Impellar kit will be very helpful upgrade for anyone with a Murray or a Craftsman made by Murray with the rectangular opening.
Thank you for the response! I'm a tinkerer so I enjoy keeping things alive longer than they should live and tend to make projects out of things that I shouldn't
Before I condemn this snowblower to an engine upgrade I'm going to put an adjustable carb on it and dial it in. Also on the to-do list this week is to adjust the governor and engine speed and see how it does. While I have the carb off tonight I intend to check the valve clearance just for the fun of it. I won't be pulling the head just yet but it will be good to know where its at.
Towards the spring I intend to do a leakdown test and see how the valves and piston rings are sealing. I suspect the exhaust valve is a little tight and will probably lap the valve while I'm in there for adjustment. That's about as far as I intend to go with this engine. If that doesn't handle the 160ft of snowbanks....its time for a Predator!
Or perhaps more likely....I'll find an older heavy duty Ariens to put the big Predator on. This is a single shaft setup so repowering is pretty easy. Same output shaft size and the bolt holes are already there for the bigger engine on the motor plate, I think I might just need to elongate a pair of the mounting holes.
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OK, ONLY FYI here....... I am not telling you what you should do.....only you can decide that..... If one of the valves is tight and you continue to run it, you risk damaging the valve guide. Once you make that guide egg shaped you are on a slippery slope of should I replace it (if you can find one) or can I still use it as is. I do not think oversized valves are available any longer for the Snow King. The lash spec on those engines is typically .008-.012". If you are down around .003 or less it would be wise to grind the valve end down to lash spec. before putting the engine back into service. Otherwise you are in that high risk category. Hand Lapping will not remove much material. Less than .001. Unless you want to spend days hand lapping. (A little comic relief). Good Luck tinkering.Thank you for the response! I'm a tinkerer so I enjoy keeping things alive longer than they should live and tend to make projects out of things that I shouldn't
Before I condemn this snowblower to an engine upgrade I'm going to put an adjustable carb on it and dial it in. Also on the to-do list this week is to adjust the governor and engine speed and see how it does. While I have the carb off tonight I intend to check the valve clearance just for the fun of it. I won't be pulling the head just yet but it will be good to know where its at.
Towards the spring I intend to do a leakdown test and see how the valves and piston rings are sealing. I suspect the exhaust valve is a little tight and will probably lap the valve while I'm in there for adjustment. That's about as far as I intend to go with this engine. If that doesn't handle the 160ft of snowbanks....its time for a Predator!
Or perhaps more likely....I'll find an older heavy duty Ariens to put the big Predator on. This is a single shaft setup so repowering is pretty easy. Same output shaft size and the bolt holes are already there for the bigger engine on the motor plate, I think I might just need to elongate a pair of the mounting holes.
@nbpt100 Thank you for the advice! Last night I replaced the idler pulleys, belts, did a full tune up and adjusted the governor arm. The governor arm was a wee bit out of adjustment so we will see if that helps keep the RPM's up a bit under heavy load.
The new stock and correct size auger belt seemed a little looser than I would like when under engagement. The idler pully arm has a new tensioner spring on it and the engagement lever is adjusted. I suspect that the belt may be slipping a bit under a very heavy load. I don't hear squealing but that doesn't mean it isn't slipping a bit. I may try a slightly shorter belt to see what happens.
On to the valve adjustment. This afternoon I'll be swapping a new adjustable carburetor on it. The one on there now is cheapy non-adjustable one. When it is running I hear what sounds like a lean flutter/pop every now and then. Might be my ears but I want to make sure its dialed in.
If I need to file the valve that's okay and I'll lap the valve to ensure a goodish seat while I'm in there. If the head needs a valve job or if the clearance is zero and the keeper is smashed..... it will be engine upgrade time. I'm not tearing it down any further or paying for machining.
The new stock and correct size auger belt seemed a little looser than I would like when under engagement. The idler pully arm has a new tensioner spring on it and the engagement lever is adjusted. I suspect that the belt may be slipping a bit under a very heavy load. I don't hear squealing but that doesn't mean it isn't slipping a bit. I may try a slightly shorter belt to see what happens.
On to the valve adjustment. This afternoon I'll be swapping a new adjustable carburetor on it. The one on there now is cheapy non-adjustable one. When it is running I hear what sounds like a lean flutter/pop every now and then. Might be my ears but I want to make sure its dialed in.
If I need to file the valve that's okay and I'll lap the valve to ensure a goodish seat while I'm in there. If the head needs a valve job or if the clearance is zero and the keeper is smashed..... it will be engine upgrade time. I'm not tearing it down any further or paying for machining.
"If it ain't broke you're not trying ". Red Green.
You'll likely tear up the other parts in short order. You can increase by 10 to 20%. But doubling is a recipe for cookiness, read as disaster.
You are probably correct. In the past few days I've had to do some rebuilding on it. I broke the gear case because I sucked up a rock and the shear pin didn't shear quick enough. I broke a couple teeth on the worm gear.
When taking it apart I was a bit surprised at how small the auger and impeller shafts were. I looked up the heavy duty units and they use 7/8" or 1" shafts. The shafts on mine were somewhere between 5/8" and 3/4".
Looking a bit more into it these particular Murray's came with up to 10.5hp and that is probably about as much as it should handle. If Harbor Freight sold a 10 or 11hp I think that it would be worth repowering this machine. I'm starting to think that if I put the 420cc/459cc engine on here it will work great...until it doesn't. Then I'll be shopping for a better machine to put the big engine on.
Current plan is to sell this one and buy an older Ariens 1328 or similar and go through it. Plenty of HD parts and they came with a 13HP engine. That machine could probably handle the 420cc/459cc engine just fine, if it even needs it.
EDIT. One lesson I also recently learned is that the big machines with powerful engines tend to use a double auger pulley setup. Years ago when they started making these machines I guess one pulley/belt wouldn't cut it and it would slip under heavy load. This machine can't be upgraded to a dual pulley setup so that makes the decision a bit easier too.
This isn’t exactly same model but specs should be the same..impeller rpm and tip speed are in the manual!
