# Sears 3.5/20 SS Worn Sprocket



## classiccat

Howdy folks, Chris here.

I have an old Sears (536.918002) that I found on the curb a few years back. I later learned that it was clearing driveways in my neighborhood since 1972. 

I also cut my "small engine" teeth (Tecumseh H35-45544M) on it so I suppose it has some sentimental value.

I had some loose chain issues last season, so I dropped a link (maybe 2...can't remember exactly) and my master link popped this season but not before wearing the snot out of the auger sprocket) .

I'm not ready to give-up on her just yet. 

Is there a source for replacement augers &/or sprockets? I can always grind the old sprocket off and weld-on a replacement.

Thanks for stoppin' by!


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## HCBPH

*Sprocket*

Not familiar with that one, but I like your idea on cutting off the old and welding on the new. I'd look at farm supply places like Fleet Farm for replacements. Good luck.


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## Shryp

536. means it was made by Noma/Murray. They are now owned by Briggs and Straton. Sears might still have parts too. Have you checked searspartsdirect.com?

You can probably get generic sprockets much cheaper from a go kart / mini bike place or a local industrial supply place. Have a look around here.
Sprockets for Go Karts & Mini Bikes | Go Kart & Mini Bike Parts | MFG Supply


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## classiccat

Thanks a bunch for the prompt replies guys!

The Auger is NLA on SearsPartsDirect. If I can't find an auger/sprocket combo (B&S or a CL Donor), I have a bead on a toro 828 that will hold me over while I patch-up Lil' Red and give her full/proper restoration


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## classiccat

Good news fellas! 

Lil' Red lives to fight another day! 

Just scored an auger/sprocket for $25.


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## HCBPH

*Congrats*

Congratulations, always good to have some spare parts and bring a blower back to life!


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## classiccat

*1 step forward...*

With my Toro project onhold at the moment, I jumped at the chance to get the replacement Auger installed on Lil' Red! (_hmmm...something is missing from this picture...what could it be_)



The auger was nearly seized to the shaft...luckily I was able to walk it out with minimal persuasion, remove the rust and lubricate the bushings/shaft with Marine triple-guard grease (Evinrude)...spins effortlessly now...especially with the larger sprocket! 

The tricky part of this job was repositioning the tension sprocket since the old mounting holes caused it to collide with the larger sprocket.



I cut a new race into the housing & sprocket arm: 




that was a step forward...


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## classiccat

*...2 steps back*

The last time that I ran this machine, it was popping / backfiring like crazy so I also popped the head for a valve overhaul / decarb: 


Nasty! That came right off with seafoam and a stiff nylon brush. I lapped the valves/seats & check clearances...all in-spec.

I figured while I was this far in, may as well check/adjust the points...*when the unthinkable happened. *



^^^ that's right...I sheared crankshaft! 

To top things off, I may have chipped the flywheel magnet...although I'm hoping it was like this before the breakdown...but I'm not getting my hopes up: 


It's hard to imagine that an engine slightly larger than a can of seafoam can power a snowblower.


Considering that I found this machine on the curb, a new crank (and possibly new flywheel) is a small investment to preserve a piece of early-70's American Iron!! 

Thanks for stoppin' by!


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## classiccat

New Old Stock Crank arrived today...


within minutes of it being in my garage, the motor was disassembled...


attached to connecting rod...fasteners treated with high-strength Loctite. Lifters installed & the shafts lubricated with Moly: 


camshaft installed & timing set (squint & you can see the tick marks on the crank & camshafts)...in this position, the camshaft slides right in without fighting the lifters: 


the old gasket was in good shape so I lightly topped it off with RTV-red & torqued-down the sump cover after 1hr setup: 


popped the head-off again & made a tweak to the intake valve: 


new head gasket coated with Permatex copper: 


all buttoned-up: 


We're getting a nice blue spark simply turning the flywheel by hand despite the chipped magnet! If it doesn't misfire I may have dodged a bullet


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## scrappy

Wow.. Pretty cool! I like that you have saved the TEC rather than slap a clone on it. 
Oh and good to see you verified the spark with the Thexton checker, one of the go-to tools for me.


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## classiccat

scrappy said:


> Wow.. Pretty cool! I like that you have saved the TEC rather than slap a clone on it.
> Oh and good to see you verified the spark with the Thexton checker, one of the go-to tools for me.


 Thanks scrappy! Cool Avatar 

Spark testers are a must have! Great for flushing out outboard ignition issues before you're up-the-creek...literally


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## classiccat

Screamed like a banchee right out of the chute! I felt that she's running well over 3500 so I had to cut it. I only had my oscillating wire tach on-hand and the machine needs to NOT be jumping all over the ground in order to get an accurate reading 

Once I get it bolted down to the machine, I'll be able to tune the motor, cut the auger chain to size and wait for the white stuff!


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## scrappy

Awesome! I have a real soft spot for the TEC side-popper.


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## classiccat

Engine idles like a kitten (a really, really loud kitten)...


However I couldn't get the high-speed working without it trying to over-rev.

After messing with every spring location, linkage position possible, I threw in the towel and tore her open again: 


...jammed-spool / stuck governor. That bullet was close...more like an RPG round


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## scrappy

Yikes! And better get a side cover gasket, that one is looking messed up.


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## classiccat

scrappy said:


> Yikes! And better get a side cover gasket, that one is looking messed up.


Yep, tore it up on disassembly 2.0  I already had the gasket onhand so we're covered. New governor gear / spool ordered.


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## scrappy

So.. did you mess up the gov during re-assembly. I don't recall any trickery back in the day. 

When you do install the new one, the manual shows a certain depth for the shaft. To me, looks like you could transfer all the plastic gears over to the old shaft.


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## classiccat

scrappy said:


> So.. did you mess up the gov during re-assembly. I don't recall any trickery back in the day.
> 
> When you do install the new one, the manual shows a certain depth for the shaft. To me, looks like you could transfer all the plastic gears over to the old shaft.


I've gotta be honest, I didn't pay the governor too much attention  but pictures of it during breakdown do show that the spool & flyweights are retracted to the proper position.

I'm going to avoid messing with the shaft...that's pressed into the sump cover. I'd have an even bigger mess on my hands if I widened that hole.


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## classiccat

If you’re seeing this and scratching your head as to how/why this would be an issue…

You set the external portion of the governor & throttle control by: 
1.) Loosen the governor tab screw so that the throttle control arm moves freely.
2.) Rotate the governor clamp/shaft clockwise to represent full-throttle position what this is doing is moving the internal control arm against the fully-retracted governor spool…the position that it would be in if the engine is spinning too slow and it needs MORE POWER!…Open that throttle baby! (_you "told" the engine that you want to go fast by moving the throttle lever up extending the external spring._) 
3.) Maintain that WOT governor position with 1 finger...and with another finger, rotate the throttle control arm so that the carb is in the WOT position…then tighten the governor tab screw.
4.) In normal operation, the cam shaft is spinning at the proper RPMs (3500)…the rotational force of the flyweights cause them to spin-out…and their little bottom levers lift the spool closing the throttle butterfly.
5.) At idle, you’re not engaging the governor & the throttle-shaft spring wins the battle by keeping it snug against the idle speed screw.

With my machine, I calibrated WOT with the no-load spool position (*the spool was stuck there*!) --> this will kill an engine in a hurry  

I'm starting to believe that this results in more thrown rods than folks realize.


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## classiccat

That spool was really stuck  the keeper was lodged under a disintegrated lip...after a few light raps with a hammer/socket: 


Cleaned-up the old gasket from the sump cover. 


The best / safest way that I've found (_from rebuilding outboards_) is with good razor (_like these big Irwin blades_) held *perpendicular* to the gasket surface. Keep the old gasket wet with denatured alcohol. Watch the gasket shavings to make sure you're not removing any aluminum.


Here's a shot of the governor design on these small frame tecs. When the spool pushes the inner governor arm, it closes the throttle. When the engine slows down, the governor retracts...and the arm follows it due to the spring tension and opens the throttle to compensate.


Lastly, we had a visitor on Sunday! The dog in my avatar has a bite on his leg to prove it...he had it coming; wouldn't leave that "poor" hawk alone


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## classiccat

when I disassembled it, the cam came out with the crankcase cover... the lifters dropped before I could see which was intake & exhaust. took a guess, slapped it back together and checked clearance...both dialed in at 0.008". 

I also wanted to check compression after it over revving...albeit it was very brief (< 5 seconds)...it sounded like a 2-stroke!  

She's still sound at 80psi (manual/pull)...dropped a bit when I went looking for my camera


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## scrappy

Now all we need is snow....just for a test run.


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## classiccat

scrappy said:


> Now all we need is snow....just for a test run.


Well...almost  I buttoned it up without the new governor to test the valves. & compession..but the new governor gear / spool arrived this afternoon 

New governor...check: 


crank / cam timing...check: 


*well-stirred* gorilla snot gasket sealing compound (_evinrude or quicksilver...same great stuff_)..check: 


snot applied liberally to each side, then skimmed-off using a drywall blade: 


gasket set in place: 


The machine dialed right in...in fact, the new governor needed more spring tension...had to go-up a hole on the governor arm !


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## classiccat

"side popper" video & some Sirometer action  

(scroll waaay down....sorry, my galaxy phone and photobucket don't get along for some reason).


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## Grunt

PUUURRRRS like a kitten, very nice job.


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## scrappy

Sounds good, love the side popper's.

When you get some snow Take a vid of it wide open.


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## classiccat

Thanks for stoppin' by guys!

I'll definitely make a vid but I must warn you in advance...This is a project thrower that's still very rough around the edges 

_missing belt/chain guard, auger drive sprocket on it's last leg, paint, etc. etc. etc._

Stay Tuned!! __


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## classiccat

Lil' Red's 1st Blood of 2015 



We got about 2" of wet snow.

Getting the auger chain dialed-in was a bit of a headache...I'm done with using master links. So for piece mind, I used a chain breaker tool to pin the end-links directly.

It's not throwing as far (I'll post a vid shortly)...I'm assuming due to the larger sprocket size. Auger simply isn't spinning as fast but there's noticeably more torque when I made a pile to drive it through...RPMs didn't budge. 

I may be welding-on a new (smaller) auger sprocket afterall!


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## classiccat

Lil' Red in action: Link. (scroll to the bottom to see the vid)

Close-up of the mechanics: Link.


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## classiccat

I crunched the #'s (and after watching the video), auger is spinning ~ 1/2-speed; I went from a ~ 1.5 to ~3 auger:drive ratio.

Auger sprocket as 44 teeth. Current drive sprocket has 15.

I think a 22 (2:1) to 25 (1.75:1) tooth drive sprocket (_keeping the 44-tooth auger sprocket the same_) will be the ticket; I want to keep a little-bit of that torque


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## scrappy

You got snow? Nothing here except for drizzle rain. Nice vid

Sounds to me the side popper is running less than 3600.


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## classiccat

Yep. Im in the Hudson Valley. Raining now though.

I checked RPMs right before i ran the carb dry using a sirometer....nuts on @ 3500. This has always agreed with the tiny tach that I cant seem to find


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## scrappy

classiccat said:


> Yep. Im in the Hudson Valley. Raining now though.
> 
> I checked RPMs right before i ran the carb dry using a sirometer....nuts on @ 3500. This has always agreed with the tiny tach that I cant seem to find


cool... would be a click of the LIKE button if it it worked.


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## classiccat

scrappy said:


> cool... would be a click of the LIKE button if it it worked.


Ditto 

I had an epiphany this morning....replace the existing shaft that has the auger drive sprocket welded-on with a keyed shaft; the belt pulley already has a keyway so we're golden 





















That will put us close to the original gear ratio (1.76)...save some of that beautiful torque...and make swapping-out drive sprockets a breeze if I've guessed wrong 

_(wouldn't a mountain bike derailer be cool???)_


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## classiccat

Winter Storm “Juno” grazed-us here in the Hudson Valley dropping only few inches…but it gave the old machine something to chew on. 



I haven’t dropped-in the new gearing because I’m really liking the added torque!It only throws 5’ but it throws 5’ regardless of whether it’s 2” or 10”…fine for clearing dog runs & sidewalks…and the little 3.5Hp tec doesn’t flinch when it hits something upto full bucket height. 

Additionally, If I approach the original gear ratio, I have to chop some of the bucket away and I’d rather not do that.

Now that I have a keyed-shaft, I can get an intermediate gear size and easily swap it out if it's not to my liking.

Another modification to the current setup that the purist in me is contemplating… swapping-out the emissions carb with an original (_courtesy of oldcman_!). I’ve gotta say, as long as you keep the jets clean (_fuel filter helps_!), this thing purrrrrrrs. 

I hope everyone here in the NE is making it through the storm safe & sound!


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## classiccat

classiccat said:


> I haven’t dropped-in the new gearing because I’m really liking the added torque!


Ahhh crud... who was I kidding. 

With Big Red out of the garage, I needed something else to bang-on I suppose.

Lil' Red's new auger drive assembly:


I'll have to trim the housing a bit tomorrow & cut a new chain.

One nice thing about this setup, if I'm not satisfied with the performance, another gear is inexpensive & easy to swap-out with the keyed shaft.


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## scrappy

Wow ..that drive gear is wasted. Post up pics of the new set up.

As for chain lube, there are some great products for motorcycle chains.


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## classiccat

scrappy said:


> Wow ..that drive gear is wasted. Post up pics of the new set up.
> 
> As for chain lube, there are some great products for motorcycle chains.


 Loose master link won that battle I'm afraid...which is why I now pin the chain directly.

I think it was Big Ed mentioning Silkolene for chains. I grabbed a small can...now I shoot that stuff on everything!


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## scrappy

classiccat said:


> Loose master link won that battle I'm afraid...which is why I now pin the chain directly.
> 
> I think it was Big Ed mentioning Silkolene for chains. I grabbed a small can...now I shoot that stuff on everything!


Silkolene, great stuff. Are you planing to reuse that drive gear with a new chain?


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## classiccat

scrappy said:


> Silkolene, great stuff. Are you planing to reuse that drive gear with a new chain?


 Oh no, that old drive gear is never seeing snow again. The side-by-side is the old shaft/gear (welded to the shaft) and the new keyed-shaft/new-gear. 

Sorry for the confusion!


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## classiccat

this shows it better. 

Top is the original; Thankfully the pulley was held-on by a set screw....easy to swap to the new shaft:


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## scrappy

classiccat said:


> Oh no, that old drive gear is never seeing snow again. The side-by-side is the old shaft/gear (welded to the shaft) and the new keyed-shaft/new-gear.
> 
> Sorry for the confusion!


Ok gotcha. That's going to be a huge change in driven speed. Now I see why the housing has to be enlarged to fit that gear. The augers will be at warp speed!


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## classiccat

scrappy said:


> Ok gotcha. That's going to be a huge change in driven speed. Now I see why the housing has to be enlarged to fit that gear. The augers will be at warp speed!


 well, it will actually spin slightly slower than the last auger...before I hosed it.

the new auger has a larger chain sprocket...hence the need for a larger drive sprocket.


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## scrappy

Sounds good! I counted the teeth and it would a 70% increase, way too much. Whats the teeth count on the auger side? Old vrs new?


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## scrappy

Does the keyed shaft ride in bushings or a ball/roller bearing?

never mind i looked at the pics in your first post, its a bearing. good


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## classiccat

Post 33 has the gear ratios....old vs new. the old auger had a 22 tooth sprocket I believe. New has 44!


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## scrappy

classiccat said:


> Post 33 has the gear ratios....old vs new. the old auger had a 22 tooth sprocket I believe. New has 44!


New driven works out to 15% slower than original. A 28 tooth would get you closer to original drive ratio. Spliting hairs I guess.


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## classiccat

Exactly! That is by design; I want to keep some of that torque!


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## classiccat

It's Alive!!!!


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## classiccat

Now that the replacement auger is spinning like it should, I felt a pretty good wobble when it wasn't throwin' white stuff.

threw it in front of a laser-level and it's out-of-alignment by about 1/4":


Some tough-love got it pretty well aligned:


Lastly, added a hardline tach/bracket...it wraps the plug wire behind the shroud.



They're predicting 10-14" Sunday/Monday...Probably "Big Red" territory but if they're off like they were this week, "Lil' Red" may be seeing all of the action! 

Thanks for stoppin' by!


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## scrappy

Nice!

I'm hoping the storm tracks further south, we are on the edge of slush and rain. Oh and do not underestimate Lil red.


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## classiccat

scrappy said:


> Nice!
> 
> I'm hoping the storm tracks further south, we are on the edge of slush and rain. Oh and do not underestimate Lil red.


 Thanks! Yeah man, little guy packs quite a punch.

Talk about contrast to last week's coverage...barely a peep to what's shaping-up to be a pretty sizeable storm!

Hope it shifts south for you guys to get a piece of the action as well scrappy!


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## classiccat

Big Red got most of today while Lil' Red sat in the garage lookin' fugly....until the mail man came 



Thank you fleabay!!! 


It's not year-correct however it works; The original was white.


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