# Bob Cat 20" re-do



## BobCat520 (Oct 24, 2013)

I've had this Bob Cat 520 since the mid 1970's, best machine I've ever owned. So about two yr's ago I decided to give it a go-over. One of the things that I never really cared for was the 5hp Briggs flathead with the floatless pumper carb so I found an OHV Briggs on ebay that had the 6:1 reduction box and proceeded to make it fit. Not to difficult, same mount holes just a bit of cutting on the driveside bulkhead to fit the larger gear case, and then fabricate some shrouding to make the engine winter worthy.
While I was into it I fab'ed a new scraper, and changed the impeller shaft and bearings (which as it turned out didn't need to be replaced)
Anyway, this machine with the new OHV engine now runs even stronger than ever, and the low speed operation is far smoother than it was with the pumper carb motor.


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## db9938 (Nov 17, 2013)

Nice job, and just out of curiosity, did the original engine have a reduction gear?


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## liftoff1967 (Jan 15, 2014)

NICE JOB. Very nice!


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## GustoGuy (Nov 19, 2012)

BobCat520 said:


> I've had this Bob Cat 520 since the mid 1970's, best machine I've ever owned. So about two yr's ago I decided to give it a go-over. One of the things that I never really cared for was the 5hp Briggs flathead with the floatless pumper carb so I found an OHV Briggs on ebay that had the 6:1 reduction box and proceeded to make it fit. Not to difficult, same mount holes just a bit of cutting on the driveside bulkhead to fit the larger gear case, and then fabricate some shrouding to make the engine winter worthy.
> While I was into it I fab'ed a new scraper, and changed the impeller shaft and bearings (which as it turned out didn't need to be replaced)
> Anyway, this machine with the new OHV engine now runs even stronger than ever, and the low speed operation is far smoother than it was with the pumper carb motor.


Nice. I never much liked my old Tecumseh either and your modern OHV Briggs will even use less fuel all while making about 2 extra horsepower too. Post a video of it throwing snow. I heard the BOb-Cat machines can really toss the snow.


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## Driftbreaker (Oct 17, 2014)

nice, I have the same one, I have only been able to use it one time since I just got it, my engine runs great though and it threw the slushy wet snow pretty good.

heres mine


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## detdrbuzzard (Jan 20, 2012)

now you have a true modern classic, nice repower


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## GreenMtnMan (Jan 5, 2014)

Good job, a Bobcat is on my wish list.


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## Shryp (Jan 1, 2011)

The augers on these things always look so flimsy to me by the standards of other machines of that vintage. Has anyone ever had any issues with them getting bent?


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## tinter (Apr 20, 2014)

Cool machine. Quite the augers.


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## dbert (Aug 25, 2013)

I like it a lot.
I'll bet those augers are twice as thick as any others, and they are welded to fat solid steel bars. Having only one support makes it look flimsy, but I'd still bet you could take a sledge hammer to them and they would be stronger than the typical auger construction.
Then again, I could be wrong.


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## db9938 (Nov 17, 2013)

They look like the paddles in a mortar mixer.


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## 69ariens (Jan 29, 2011)

Nice job. what shade of orange is that.


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## micah68kj (Oct 8, 2011)

Very nice job. You put some quality time in to that restoration.


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## BobCat520 (Oct 24, 2013)

Thanks Folks
All of the Bob Cats use an engine with a 6:1 reduction box. The auger and impeller are far stronger than any other machine that I've seen, they carve through a half frozen plow berm like it wasn't even there and will toss wet or dry snow and even slush the hard part is to remember to drop the nose on the deflector to keep the through from going onto someone else property. Another couple of things that I've changed, swapped the OEM tires & chains for a pair of Carlisle Sno Hog's, and added a handle bar mounted throttle control so I could drop the RPM's when shifting as Bob Cats have for real chain and cog transmissions, not the usual wheel on wheel trans that is so common today.


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## BobCat520 (Oct 24, 2013)

For 69ariens ..almost missed your question. The belt guard and inside of auger housing have Krylon Pumpkin Orange spritz'd on them. The rest of the machine still has the OEM paint.


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## Geno (Nov 29, 2011)

I wonder why they went away from that impellor design? I know simplicity and early mtd used that design too. I imagine due to production cost and also bit longer than average blower. I had them and they are built like a tank. The later ones went to plastic belt cover and I think that was the only weak link as they tended to crack (mine did and saw another did)- I almost bought couple mtd ones month ago with the paddle wheel- but passed. Bob-Cat is superior for sure.


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## HCBPH (Mar 8, 2011)

*Bobcat*

Now that's a sweet looking machine. That impeller design always reminds me ofc a couple of pieces of farm equipment. I've never used one but wouldn't turn down the chance to try one out if the opportunity ever presented itself.

What kind of drive mechanism does that have - friction disc?


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## BobCat520 (Oct 24, 2013)

OK the motor to to the trans and auger drive use two v belts, then chain drive to the auger shaft. The internals (transmission) is chain and sprockets, and drive dogs. No friction wheel drive. Most consumable parts on the machine (chain,bearings,shafts,belt) are easily found in any power transmission supplier. The only glitch is one of the two belts is a propose built belt that is an off beat length and pitch which was Wisconsin Marine's way of locking buyers to them. There is however a small engine shop in Pougkeepsie N.Y. that has them reproduced and usually sells them on ebay.


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## mnichols567 (Oct 20, 2018)

Would you have any specs on the scraper blade that you fab'd up? I need a new one but I'm unable to find a replacement or the specs to have a new one made.


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## marspatt (Dec 4, 2014)

BobCat520 said:


> I've had this Bob Cat 520 since the mid 1970's, best machine I've ever owned. So about two yr's ago I decided to give it a go-over. One of the things that I never really cared for was the 5hp Briggs flathead with the floatless pumper carb so I found an OHV Briggs on ebay that had the 6:1 reduction box and proceeded to make it fit. Not to difficult, same mount holes just a bit of cutting on the driveside bulkhead to fit the larger gear case, and then fabricate some shrouding to make the engine winter worthy.
> While I was into it I fab'ed a new scraper, and changed the impeller shaft and bearings (which as it turned out didn't need to be replaced)
> Anyway, this machine with the new OHV engine now runs even stronger than ever, and the low speed operation is far smoother than it was with the pumper carb motor.


Proud owner of a sister machine, 1978 SN 19549. Looking for a parts diagram. Can you, or anyone, help, please.

Thanks.


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