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Discussion Starter #1 (Edited)
Is it really 2.75" diameter? Is anyone on here with that pulley can confirm?
The one that I have is 2.5". The Internet seemed to mix it up a lot. They would say that it is the SHO sheave and 2.75" diameter, but when I counted the pixels, it was only 2.5".
 

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Discussion Starter #3
Yep, just measured my D28SHO and the drive pulley is 2.75".
Thank you so much for that. You got your hand dirty to measure it for me.
Knowing its true diameter, I'm now confident to order it.

Thank you, again. You are awesome.
 

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Discussion Starter #4
For the next person, I want to say that the SHO pulley has the words SHO and PRO stamped on it. The other one has the same ID number, but only 2.5" diameter. They like to mix them up.
 

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Unless you have a tight belt length tolerance, I don't think that little difference will matter much. There probably is enough play in the belt adjustment, to take care of that.
Sid
 

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Discussion Starter #7 (Edited)
With a large impeller, that little pulley different does make a different. It is like the impeller mod, but better. It is how the Deluxe SHO and Pro got the higher output. They throw farther, too. I can see the different.

Where I live, the most we would get is 12", so engine size is not going to be a problem for me. Plus, the flat head Tecumseh has more displacement. They seem to maintain rpm better than the newer ones.

Some Hondas have less hp and torque, but faster impeller speed. I'm not too crazy for throwing distance, but I would like to see more out of my snowblower.

My only concern is the belt length. Hopefully, I will not need new belts. I will do some research beforehand.
 

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Discussion Starter #8
It is very likely that I will need new belts for that.

My belts were 39.5" in length. Last time I checked, they had a tight tolerance. So, finding an extra 0.5" out of them is going to be hard.

The SHO models uses 41.5" belts, but I think their crankshafts sit higher.
 

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Discussion Starter #9
I have the new SHO sheave pulley with me right here.

It turned out that my snowblower was already equipped with the SHO sheave pulley 2.75", just like I first thought.
It is a ST824E, or Deluxe 24 (one of the first models in the 921 series), so it had that 2.75" pulley vs. the 2.5" pulley on the newer deluxe models.
The auger pulley is the same 8.5"

It should have 1080-1100 impeller rpm at 3500 engine rpm.

Some members on here confused me with their numbers, so that messed up my calculations and measurements.
 

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I have the new SHO sheave pulley with me right here.

It turned out that my snowblower was already equipped with the SHO sheave pulley 2.75", just like I first thought.
It is a ST824E, or Deluxe 24 (one of the first models in the 921 series), so it had that 2.75" pulley vs. the 2.5" pulley on the newer deluxe models.
The auger pulley is the same 8.5"

It should have 1080-1100 impeller rpm at 3500 engine rpm.

Some members on here confused me with their numbers, so that messed up my calculations and measurements.
My machine when new had engine rpm of 3,450 and turned the impeller at 1,040 rpm. I moved the governor spring to the outer hole on the governor arm which increased engine rpm to 3,700 and impeller speed to 1,110 rpm.

The Ariens spec for 1083 rpm for the impeller requires engine rpm of 3,600.

The Pro models turn the impeller at the same speed as the Platinum due to the same engine speed (3,600 rpm), engine pulley diameter (2.75"), impeller pulley diameter (8.5"), and impeller diameter (14"). It is not clear where Ariens get their 1,112 impeller rpm from unless the engine rpm is 3,700 rpm. Owners who have checked the engine rpm seem to confirm 3,600 rpm though.

Engine rpm will vary a little from "stock" 3,600 rpm due to the fixed end of the governor spring being a bent engine cooling cover. Seems a lot of users are reporting 3,500 approx for the stock engine. Stock is 3,600 rpm with plus or minus 100 rpm, so stock engine can run 3,500 to 3,700 rpm and be technically within spec.
 

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Discussion Starter #11
My machine when new had engine rpm of 3,450 and turned the impeller at 1,040 rpm. I moved the governor spring to the outer hole on the governor arm which increased engine rpm to 3,700 and impeller speed to 1,110 rpm.

The Ariens spec for 1083 rpm for the impeller requires engine rpm of 3,600.

The Pro models turn the impeller at the same speed as the Platinum due to the same engine speed (3,600 rpm), engine pulley diameter (2.75"), impeller pulley diameter (8.5"), and impeller diameter (14"). It is not clear where Ariens get their 1,112 impeller rpm from unless the engine rpm is 3,700 rpm. Owners who have checked the engine rpm seem to confirm 3,600 rpm though.

Engine rpm will vary a little from "stock" 3,600 rpm due to the fixed end of the governor spring being a bent engine cooling cover. Seems a lot of users are reporting 3,500 approx for the stock engine. Stock is 3,600 rpm with plus or minus 100 rpm, so stock engine can run 3,500 to 3,700 rpm and be technically within spec.
Thanks for the info, Town. Based on my research and knowledge, it is hard to know the true rpm of the impeller (unless you measured it directly with a laser gun, or something). As it turned out, the rpm is also depend on the belts and the power of the engine. Raw belts carry most load at their tensile cords, so the diameters use for ratio is near to the top of the belts (about 1-2 mm below the top of the belt). When the belts sat in the pulley, I saw their tops were outside (above) of the grooves by 1-1.5 mm. That seemed to be where their tensile cords were.

I haven't seen many snowblowers running at 3600 engine rpm stock, so it is BS, when they measured 1080 rpm at 3600 engine rpm. Most of the time, they run at 3450-3500 rpm stock. My calculation show that, I would get 1080 rpm at 3500 engine rpm. That was with the rpm lost when under load. And, to be honest with you, 1080 impeller rpm isn't fast at all. Considering that the impeller is only 13.5" (not 14" like they said). Some Ariens Sno-tek have the same impeller tip speed. The ariens ones just have a larger scoop and throw at a larger volume.

Well, that is just my estimation, I'm not going big like you. My engine is only 8 hp. You taxed your engine a lot by going that big. If it throws too far, it will be hard to aim the snow as well.
 

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Discussion Starter #12
I saw one of your posts. I agree with you that cog belt and Kevlar seem to be the best option if you can find one. Too, bad, they only have wrapped kevlar belts.

I replaced with a cog belt on another snowblower that I have. It seemed to have grabbed better .Therefore, I had to adjust the brake and belt keeper. Cog belts can be a problem. Don't think the Ariens with dual pulleys need cog belts. My belts are still perfect. The rubber maybe hard, but I'm cheap.
 
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