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kellycaudle

Active member
IHCC Supporter
Joined
Jun 24, 2020
Messages
42
Location
Piedmont SC
displayname
Kelly Caudle
I have a 1983 Cub Cadet 680 Hydro with the 38" mower deck attachment- I have enjoyed it and I look for ward to restoring her when I retire. thanks
IMG_0692[1].JPG
 
Welcome Kelly - your 680 looks like a nice machine (from the distance in your pic). When are you planning to retire (and restore)?
 
Kelly - in the last pic you posted I see the box around the muffler is missing. Do you have these parts? The muffler box along with the side panels (which you do have) are important parts that help keep the hot exhaust air away from the engine.
 
Kelly - in the last pic you posted I see the box around the muffler is missing. Do you have these parts? The muffler box along with the side panels (which you do have) are important parts that help keep the hot exhaust air away from the engine.
No, I haven’t ordered the box yet, or the grill/grid parts. I was just waiting but I thought it was only for noise reduction- if it impacts the engine then I will get the box ASAP
 
Well Kelly - I'll probably start some controversy here since it's somewhat hard to say the missing muffler box impacts the engine. IH started using the Kohler K "AQS" engines in the Quiet Line series starting late 1974. It was the first time IH had fully enclosed the engine with side panels. Kohler had designed the engine air flow from the flywheel fan to flow across the head for cooling and the air to also flow to the carb. It's not a tight seal to the carb and it's not really forced air flow like a turbo. I believe the idea was mostly to help quiet the engine and allow manufacturers to enclose the engine (i.e. side panels). The muffler was enclosed in a box to both help quiet the engine within the panels and to help keep the hot exhaust air from flowing back to the flywheel. IH had the muffler exhaust pipe exist in the front of the tractor thru the grill. I guess this helped make it seem like the engine was "Quieter" compared to the earlier versions with no side panels and the exhaust existing on the right side of the tractor - where the operator would tend to hear it more than in the front of the tractor.

Now - the big question you raised is "does the muffler box impact the engine". I'd like to say "yes, somewhat". To know for certain someone would have to measure the engine temperatures with and without the muffler box installed. It's probably not a great deal, but temperature can make a difference to an air cooled engine. I generally think without the box the other parts of the engine will be operating at slightly hotter temperatures than if the box was installed. How "much" does it impact the engine? Probably not a whole lot. Will it shorten the life of the engine? Well, maybe, but I don't know how you'd ever figure out the answer. Maybe there are some experts on here that can advise a little better.
 
I certainly understand the airflow generated by the flywheel and the positive impact on the engine and noise reduction from the box. I will post a before and after series of pics after I get the box and grill put on soon. Thanks for the interesting discussion so far- great group!
 

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Kelly - before you go getting the tin muffler box have a good look at the aluminum duct on the back side of the muffler. It should have several screw holes where the tin (actually very light steel) muffler box is held to it with screws. Often times this aluminum duct is cracked or the screw holes are wallowed and won't hold the parts of the tin box. I see Charlie at CC Specialties has the tin muffler box, and price is fairly reasonable for a brand new box. Charlie also has the aluminum duct the box mounts to but make sure you're sitting down if you need one.

Also, David Kirk at "Kirk Engines" (linked above at the colorful boxes too) has an item he calls the Muffler "Krutch", ops guess he really calls it Crutch. This thing really works and will save your aluminum duct plate from cracking. See it at this link.
https://www.kirkengines.com/index.php#MufflerCrutch
 
That duct is new so I’m good, and I did see the box was reasonable. Thanks for the resource and now you got me excited about getting that front end done . I’ve been putting it off since I have several other babies that tend to. The Cub is my favorite though
 
Sounds good Kelly - please let us know how you make out. Pics are always great.

Also, another FYI thing I should'a mentioned about having the muffler box. It doesn't really fall under engine performance but I believe if you do "not" have the muffler box installed the electric PTO mounted below the muffler will get hotter than normal and could fail sooner - and they ain't cheap.
 
Maybe you only need the field coil assembly. Worth checking to see. I believe Charlie at CC Specialties has the field assembly and the complete PTO.
 
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