# Engine Swap



## SumoLumo (Nov 27, 2011)

Hi Sorry for the newbi question but I been searchin everywhere with no luck... I have a 5HP yard machines by mtd snow blower with a tecumseh engine that locked up. My friend had a 5 HP troy built with a briggs engine on it.. His engine is fine but his blower was crushed in an accident.. Question is can these motors be swapped straight up or do i need to do anything special....
Thank you for any help 

Rick


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## Shryp (Jan 1, 2011)

The should be close enough that they will work pretty easy. Might need to drill new holes.

The important thing to do is figure out if the engines have 1 shaft or 2.


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## SumoLumo (Nov 27, 2011)

The Tec has 1 shaft. Didnt see the briggs yet
Hope the engine rotations are the same.


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## HCBPH (Mar 8, 2011)

*Swaps*

Things I can think of when considering a swap: # of shafts, diameter and length of shafts, carburetor linkage, motor HP, recoil vs electric starter. Distance from centerline of shaft to surface, bolt hole location.
If those work out, it would be a go for me to swap.


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## Shryp (Jan 1, 2011)

If your old engine is 1 shaft, it doesn't matter if the new one has 1 or 2 shafts. You can leave the extra shaft empty as long as it fits under the belt cover. Shaft length is somewhat important in that it needs to be long enough to reach the augers. Too long can be cut down or just stuck through a hole in the belt cover. Diameter can be important, or you can buy new pulleys. Height from bottom of engine to center of shaft could be important. If you are too tall on the new engine the belt cover won't fit. If longer/shorter and you can make the belt cover work just add the difference x 2 to the length of the new belts.


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## SumoLumo (Nov 27, 2011)

Just pulled cover off my blower. It does have 2 shafts. 
Now i just hope the briggs engine has 2 shafts
The engine that i want to put on it is off a troy built 

Hoping their the same. Knowing my luck they wont be 

Does briggs and stratton engines have 2 shafts 
Thanks. As i wont be able to see the briggs engine untill this weekend


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## CarlB (Jan 2, 2011)

SumoLumo said:


> Just pulled cover off my blower. It does have 2 shafts.
> Now i just hope the briggs engine has 2 shafts
> The engine that i want to put on it is off a troy built
> 
> ...


Some do some don't, you 'll just look and see.


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## SumoLumo (Nov 27, 2011)

Confirmed. My blower engine has 2 shafts. Main shaft and a smaller shaft that has another pully. The other engine only has the main crank shaft engine but there is a spot that is plugged where the smaller pully would go. 
Question now is. What would need to be done to make the engine work that only has i shaft 

Engines are identical accept for that configuration 
They both have same carb same tank same plug. 

Can this single shaft engine work with out modifing anything 

Thanks to all for helping. 

Rick


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## SumoLumo (Nov 27, 2011)

The other engine is not a briggs but a tecumshi. Sorry for the poor spelling


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## HCBPH (Mar 8, 2011)

*Motors*

Tecumseh has produced both single and dual shaft engines. Take this with a grain of salt as I have not had 2 apart to compare the internals.

I suspect the cam and cover are the main differences between the the single and twin shaft engines. Could you turn a single shaft into a twin - possibly if you have a parts engine available or a good machine shop.
If they are otherwise identical, I would think you could probably remove the cover on the shaft side of both engines, swap out the cams and covers and convert a single shaft to a twin.

Is this for the faint of heart - no. Is this for someone without sufficient tools or mechanical knowledge - no. Is this for someone who can't read a manual and interpret disassembly and assembly instructions - no.

You can't just put a single shaft engine on your snowblower if it previously had a twin shaft. The 2d shaft for the drive is running off the end of the camshaft, which means its running opposite the main shaft, plus it's running at half the speed of the main shaft. If you rigged it up, all your forward speeds would be reverse and reverse would be your forward gear. You could do some modifications to make it work but that could be both very time consuming and expensive in the long run.

Unless you feel up to it, best to find a correct engine and go from there. Good luck.


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## kb0nly (Sep 22, 2011)

Could one use a idler shaft of some sort???

I have been pondering how to adapt these dual shaft blowers to a newer single shaft engine. I see them all the time around here, dead due to the impossibility of swapping on another motor easily.

I was thinking of making something. A idler shaft and a couple gears, so that the main shaft drives the secondary shaft through the gears, thereby reversing its direction. The only question is... Does anyone know what the RPM of the camshaft is when the engine is at full throttle... Example, the crankshaft is spinning at 3600 RPM so the camshaft is spinning at?

I don't think i could make something that would fit under the stock belt cover though. The problem of course is getting it spinning in the opposite direction. Not too many choices there.


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## Shryp (Jan 1, 2011)

The camshaft spins at half speed, so 1800 RPM. A chain drive might work better than a belt drive since you wouldn't need the chain to have the same amount of contact as a belt.


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## HCBPH (Mar 8, 2011)

*Secondary shaft*

I think about the only way to get the counter-rotation would be a gear drive between the original shaft and the secondary which then means getting the right gears and have them mesh correctly and how would you lube them? Then you'd have to cut some form of keyway for the extra gear on the primary shaft, which I'm guessing that to cut a new keyway into the pulley shaft means pulling the crankshaft to get a key cutter at it in a mill. Now you'd have to fully support the aux shaft on both ends so it wouldn't pull which most likely would mean a bearing on either end of the aux shaft. I would think then it would have to be bolted to the face of the engine, so alignment becomes critical here too. All this would mean you'd likely have to use something like a segmented belt on that additional shaft or unbolt everything to change out the belt. After all that, you'd still need things like undoubtedly making your own belt cover, probably have to rebuild the idler due to changes in belt geometry, etc.

Just seems like an awful lot of headaches and machining work for a small payback IMO. I'd just look for a different engine, seems like it would save alot of gray hairs vs trying to make a single shaft one work. That's my opinion.

PS - I'd love to see you pull it off, but unless you have access to alot of machine tooling I don't know how to do it. If determined, I'd look into the cam swap idea, if it's possible it would be alot less headaches and likely you could use oem parts.


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## SumoLumo (Nov 27, 2011)

Do manufacturers still make engines with 2 shafts ?? Main shaft and then the camshaft ??


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## td5771 (Feb 21, 2011)

I don't remember what site it was on but I found a site and punched in 2 engines looking for a replacement. an hs40 and an hs50 both with double shafts. they came up with an engine for both. they were single shaft engine but a footnote for thew new engine stated "must use old engine crank case cover and camshaft.

I will see if I can find it.


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## tractornutmn (Nov 30, 2011)

If you find that post it up!!!

Yeah i know the logistics of making a single shaft engine into a dual is filled with problems. But being good at building stuff like this and knowing others who are, i just think there is a way to do it.

I am basically looking at one way to do it. Adding a chain sprocket to the back end of the main pulley, all the machining would be done to that pulley and could be as easy as a sprocket with spacers welded/bolted to the back of it.

So how do i get counter rotation?

A plate with a shaft end bearing, its a self supported stub shaft and bearing mounted to a plate which gets bolted to the front of the engine, it will have a chain sprocket and belt pulley on it, then below and slightly to the right of that shaft is a chain idler sprocket, so that the secondary shaft rides on the top side of the chain, effectively making the main shaft turn the secondary shaft clockwise. The idler sprocket is mounted in a slot so it can be adjusted to tension the chain. Just think of a chain running between two sprockets with an idler in the center, the secondary shaft is like that idler, getting spun in the opposite direction.

All together the parts would be about $100, but would allow use of any single shaft motor. I don't have the money to pull this off right now, but i have an Ariens blower with a twin shaft motor on it thats blown up, hole in the block. When i can afford it i plan on buying a GX Clone and the parts to try fabricating this.


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## tractornutmn (Nov 30, 2011)

Shryp said:


> The camshaft spins at half speed, so 1800 RPM. A chain drive might work better than a belt drive since you wouldn't need the chain to have the same amount of contact as a belt.


That makes for easy math on the chain drive, its a 2:1 drive then.


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## kb0nly (Sep 22, 2011)

Ok so the camshaft spins at half the speed... Then a 2:1 drive would be easy to make.

I am working on some ideas... Nothing solid yet but me and a couple friends that have the machining experience could put my idea together.


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