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MTD 990 Twactor Guy
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Need some input.

I'm working on my MTD 990 - pictured in the avatar at left - and I want to change the exhaust to an upswept stack. I know some of you have done it.

What did you use, where did you get it, or how did you make it?

Photos, please! :wwp: Thanks much! :thanku:
Rich
 

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All you need is the right size pipe to thread into the engine,a 90 degree elbow or two,and a pipe adapter to increase it to a larger pipe with a 1-1/2" O.D. (1-1/4" pipe nipple) and a stack,glass pack muffler,etc for the upright..and a few clamps if your not going to weld or braze the stack on..a rain cap or curved outlet will be needed too..

Its almost a must to support the stack some way ,so the weight of it and vibration wont eat away at the threads in the engines exhaust port..it'll help keep it from drooping over when the engine heats up and expands too..I have used the bomb shaped resonators off an old cars exhaust system as the muffler and stack,they work well and are pretty quiet...
 

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I used a Cub Farmall muffler (from TSC) on my JD 67-112 w/ HH100 Tecumseh! Took a pipe nipple & the muffler to a local muffler shop, they bent the tubing & welded it to the muffler for me. I then clamped it to the 6" pipe nipple. If you have much viabration you will need extra support, mine didn't.
 

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I used the same muffler as grnspot110 on my Onan, My pipe isn't quite as nice LOL as I used emt conduit , cut and welded my offset. Needed these to get the pipes outside of the hood. My is set up with duals.


 

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I used a 1" street ell and welded on a piece of 1 1/4" to get out side of hood. I then used a 1 1/2" 90deg bend cut from a motorcycle pipe and a motorcycle muffler.
 

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I think its mostly the looks that most of us want ,but the fact the carbon monoxide isnt blowing back at face level is a plus too,especially on some engines that burn a bit of oil or really "stink" of that C-O smell...the stack gets it up over your head..they sound cool too!..
 

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I agree with Tractor-Holic but, on my Onan I did see some improvement in performance. It may be due to the age of the motor as well as it is an early 80's.
 

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made mine from a old load lock , and extra pipe , got the cap from tsc .

shd
 

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The raised pipe(s) look and sound nice when done properly, BUT in my mind, they are a safety hazard.
A hot unprotected exhaust pipe can burn exposed skin rapidly, if bumped into, accidentally.
The location of the exhaust outlet looks to me to be about face height. The exhaust (and other exhaust particulates) will be pushed towards the face by the wind currents. Those particulates could be dangerous to the nose and eyes, not to mention the hair. Requires protective head gear.
If there is such an improvement, why don't the engine/mower manufacturers offer them as an option?
Re-routing the pipes downward and out the rear of the tractor by the hitch would seem safer, but then, the mower deck might have to be removed, and, the driver would then be sitting over the exhaust pipes.
One benefit of either system, you can tell when the motor starts to burn oil.
 

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I added a stack to my Murray last year...
Is that a Cherry Bomb muffler? Nice colour.

Rather than a flapper, I would turn the end out sideways to help keep it out of your face. Haven't seen any red ones to colour match a red Cherry Bomb muffler though.
 

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The jury is still out on that one for me. I had 2 friends that had cracked blocks from extending the muffler out to far and not retaining them well.
 

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Soup cans work great and let's one pratice their catching when they forget to remove before starting.
 

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I'd rather catch the soup can,than get a shower after starting an engine that has a stack,that you forgot to put one over!..we often forgot to put the hub cap on the loaders stack at the junkyard we used to cover it up,and the next
morning after a heavy rain ,you'd start up up ,wind it up,
and get douched with rain water and diesel soot!.. :(

The first exhaust stack I remember was one my older brother put on a Clinton we had on a go-cart..a neighbor brazed a 1/2" pipe nipple to a VW Beetle tail pipe chrome tip "silencer" thing for him,it looked cool and sounded great,it was glass packed and had a perforated core..you could buy them for like 5 bucks back then!..soon every kid in the neigborhood with a mini bike or go cart was wanting one too!..
 

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The raised pipe(s) look and sound nice when done properly, BUT in my mind, they are a safety hazard.
A hot unprotected exhaust pipe can burn exposed skin rapidly, if bumped into, accidentally.
The location of the exhaust outlet looks to me to be about face height. The exhaust (and other exhaust particulates) will be pushed towards the face by the wind currents. Those particulates could be dangerous to the nose and eyes, not to mention the hair. Requires protective head gear.
If there is such an improvement, why don't the engine/mower manufacturers offer them as an option?
Re-routing the pipes downward and out the rear of the tractor by the hitch would seem safer, but then, the mower deck might have to be removed, and, the driver would then be sitting over the exhaust pipes.
One benefit of either system, you can tell when the motor starts to burn oil.

As Tractor-Holic stated most of this is for looks and sound and does not always improve performance. It may in some cases. Yes they can burn you if you bump them as can any exposed pipe or hot component on a piece of equipment. Some older larger GT's did have stacks on them primarily diesels. As far as exhaust in your face my pipes are a good 4"-6" above my head when on the tractor but, then again I'm only 5'6" LOL:ROF . The force of the exhaust pushing out of the pipe pushes it way out of the way. I have been running mine for a couple of years now and have had no issues with this kind of a problem. Running the pipe out the back to me could case problems with trannies and hydros overheating.
 

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What experiences have you all had with 'stacks', while plowing snow during storms, with all that white stuff (snow) blowing around you?

I can see stacks working properly while mowing the lawn or tilling the plot, but during adverse conditions, they may not work like they were designed.

And, no, the lawn mower is the same tractor as the snow plow, and the same as the snow blower.
 

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I think having the stack a bit closer to you,rather than way up front,actually lets LESS exhaust get in your eyes and nostrils,and of course it has to be a good 6" higher than YOU are,sitting on the tractor..just keep it far enough away so you wont touch it while reaching for a control lever or something.
Remember,TOO high isn't good either--you'll be hitting tree branches,low doorways,and clotheslines,etc!..I find a stack a pain sometimes for this reason out in the woods when collecting firewood..

If its too far forward the gasses fall down as they leave the stack,and end up right in your face..better off having it almost to the rear of the hood where it'll blow up and over your head..a curved outlet will direct the gases away better than a straight end with a rain cap will,or one with a bolgna sliced end..

As for snow,I never had any issues with a stack while plowing or useing a snowblower on a tractor..in fact I liked having one,because they made a dandy hand warmer,and considerable heat is thrown off a big muffler too..:D

A guy not far from me took an old Sears lawn tractor with a plow and enclosed the whole thing in a plywood "cab" that looked like a flat fendered Willys jeep,he even had a windsheild made of plexiglass and real widsheild wiper from a car he rigged up to it.. he put the exhaust stacks outlet,which was a cherry bomb glass pack muffler like the one on the Murray pictured on this thread, out through the roof of it,and he claimed it kept him quite cozy while plowing his driveway..I remember seeing him light his cigarettes on it too,I laughed at that!..
 
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