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Archive through March 10, 2011
- Thread starter kmcconaughey
- Start date
Help Support IH Cub Cadet Forum:
- Joined
- Dec 21, 2007
- Messages
- 220
- displayname
- Aaron Schmidt - Xtreme Motorworks
Don T, May you be blessed with a speedy recovery and everything turns out ok. Your advice, comments and humor is always appreciated. Aaron
STEVE B., WES - I have to agree, I think a #30 carb is too big even on a K321. Too bad there isn't something between the #26 & #30. The K341 in Wyatt's was a BEAST... It'd sit there and idle about 1000 RPM, jab the hydro lever forward as far as you dared and it'd pop the frt wheels in the air and the engine would pop once, maybe twice... and then speed away still idling @ 1000 rpm.
KOHLER did a great job at building & spec'ing the K-series to use interchangable parts. They almost made the engines too easy to hop up.
KOHLER did a great job at building & spec'ing the K-series to use interchangable parts. They almost made the engines too easy to hop up.
dwilkinson
Well-known member
- Joined
- Nov 9, 2008
- Messages
- 46
- displayname
- Doug Wilkinson
Donald T.
I'm hopefull you have a speedy and complete recovery.
A fellow Canadian from Ontario.
I'm hopefull you have a speedy and complete recovery.
A fellow Canadian from Ontario.
A big one and a little one thinking things over, back in 61.
- Joined
- Aug 23, 2006
- Messages
- 2,912
- displayname
- Allen Schumacher
Or maybe the driver of the 'O' panicked and crashed when he saw the bucket overhead ! ?
An appropriate time to chime in…
Don T. – Wishing you the very best for a rapid and complete recovery! Keep us informed of your progress.
Carburetor venturi size – I think we’re all on the same page here, in that a #30 with its .935 inch venturi diameter is too big for a 29.2 cubic inch K301 engine for overall performance. It’s easy to get the notion that “the bigger the carburetor, the bigger the power” and this is just not true. The problem is magnified more when we’re dealing with a single cylinder engine…air flow through the venturi is not steady (as in an engine of 4 or more cylinders) but highly intermittent. This aggravates the carburetion problem. In a hot rod V-8 with gobs of carburetors, air flow is very steady and this trait, combined with a mondo accelerator pump, can allow the engine to run somewhat acceptably at low speeds. We don’t have the luxury on a single cylinder Kohler engine.
Carburetor venturi diameter is determined from engine airflow requirements at the design speed. Knowing the displacement and rpm of the engine at rated power, and assuming an average intake air temperature, one can calculate the average velocity through the venturi during the inlet stroke. This velocity number is very important – too high (small venturi) and the carburetor will be too restrictive to air flow…too low (large venturi) and acceleration and low speed running quality will suffer.
In dealing with carburetor design issues, a convenient term to use is the Mean Mach Index, or “Z”. This is simply the average velocity of the air through the venturi during the inlet stroke, divided by the speed of sound through air (at 70 deg F, this is 13,540 in/sec).
For most small single-cylinder industrial engines running 4000 rpm and below, “Z” should be at a value of .45 to .55. This will yield an engine with good top end power and nice low end manners as well. The stock K301 running 3600 rpm wide open throttle at 100% volumetric efficiency consumes 30.4 CFM of air, or .0169 cubic feet per inlet stroke. With a #26 carb (.81 inch dia venturi), “Z” turns out to be .502, right where we want to be. Now equip the same engine with the #30 carb with its .935 inch diameter venturi. Under the same conditions, “Z” calculates out to be .38 – way out of the ideal range. The lower the “Z” value, the lower the air velocity through the venturi, and the poorer the carburetion at low speeds. However, this has a beneficial effect on top-end power as lower velocity means less restriction to air flow. If we’re building a puller engine and plan to turn it up to 7000 rpm, the venturi will need to be bigger to move the increased airflow that the engine demands. Here we don’t care about low speed running quality and “Z” can be down in the .3 range. But these engines aren’t subjected to the broad operational running range that a standard garden tractor engine is.
Bottom line (sorry if I blew up) is that a #26 is just right for the K301 for clean carburetion from idle up to 4000 rpm.
Don T. – Wishing you the very best for a rapid and complete recovery! Keep us informed of your progress.
Carburetor venturi size – I think we’re all on the same page here, in that a #30 with its .935 inch venturi diameter is too big for a 29.2 cubic inch K301 engine for overall performance. It’s easy to get the notion that “the bigger the carburetor, the bigger the power” and this is just not true. The problem is magnified more when we’re dealing with a single cylinder engine…air flow through the venturi is not steady (as in an engine of 4 or more cylinders) but highly intermittent. This aggravates the carburetion problem. In a hot rod V-8 with gobs of carburetors, air flow is very steady and this trait, combined with a mondo accelerator pump, can allow the engine to run somewhat acceptably at low speeds. We don’t have the luxury on a single cylinder Kohler engine.
Carburetor venturi diameter is determined from engine airflow requirements at the design speed. Knowing the displacement and rpm of the engine at rated power, and assuming an average intake air temperature, one can calculate the average velocity through the venturi during the inlet stroke. This velocity number is very important – too high (small venturi) and the carburetor will be too restrictive to air flow…too low (large venturi) and acceleration and low speed running quality will suffer.
In dealing with carburetor design issues, a convenient term to use is the Mean Mach Index, or “Z”. This is simply the average velocity of the air through the venturi during the inlet stroke, divided by the speed of sound through air (at 70 deg F, this is 13,540 in/sec).
For most small single-cylinder industrial engines running 4000 rpm and below, “Z” should be at a value of .45 to .55. This will yield an engine with good top end power and nice low end manners as well. The stock K301 running 3600 rpm wide open throttle at 100% volumetric efficiency consumes 30.4 CFM of air, or .0169 cubic feet per inlet stroke. With a #26 carb (.81 inch dia venturi), “Z” turns out to be .502, right where we want to be. Now equip the same engine with the #30 carb with its .935 inch diameter venturi. Under the same conditions, “Z” calculates out to be .38 – way out of the ideal range. The lower the “Z” value, the lower the air velocity through the venturi, and the poorer the carburetion at low speeds. However, this has a beneficial effect on top-end power as lower velocity means less restriction to air flow. If we’re building a puller engine and plan to turn it up to 7000 rpm, the venturi will need to be bigger to move the increased airflow that the engine demands. Here we don’t care about low speed running quality and “Z” can be down in the .3 range. But these engines aren’t subjected to the broad operational running range that a standard garden tractor engine is.
Bottom line (sorry if I blew up) is that a #26 is just right for the K301 for clean carburetion from idle up to 4000 rpm.
wchockensmith
Member
- Joined
- Sep 13, 2010
- Messages
- 11
- displayname
- walter c. hockensmith
a little help please will a sears plow and hitch fit on my cub Original..thanks in advance
Hey Guys,
Since we are on carb questions, I happen to have one. I have a 1450 and acquired a 1650. I had completely rebuilt the 1450 carb but I have abandoned that engine project and have replaced it with the 1650 K341. The 1650 carb is pretty rough. Can I put the 1450 carb on the 1650 motor? I also noticed the 1650 does not have the 1/4" spacer between the engine and the carb. Can I put that on the 1650 also? I think the 1650 carb is contributing heavily to my engine skipping. Thanks!
Chad
Since we are on carb questions, I happen to have one. I have a 1450 and acquired a 1650. I had completely rebuilt the 1450 carb but I have abandoned that engine project and have replaced it with the 1650 K341. The 1650 carb is pretty rough. Can I put the 1450 carb on the 1650 motor? I also noticed the 1650 does not have the 1/4" spacer between the engine and the carb. Can I put that on the 1650 also? I think the 1650 carb is contributing heavily to my engine skipping. Thanks!
Chad
K
kpeaney
Guest
David Kirk, very informative and useful post. Thanks.
On another topic, where do you post for homemade items? Got an idea for something and want to put it in the correct place.
Charlie, the Cub wants to come out to play. Just don't have any 'dohickies' for it to play with.
KennyP
On another topic, where do you post for homemade items? Got an idea for something and want to put it in the correct place.
Charlie, the Cub wants to come out to play. Just don't have any 'dohickies' for it to play with.
KennyP
sblunier
Well-known member
- Joined
- Aug 4, 2006
- Messages
- 4,829
- displayname
- Steve Blunier "Mr. Plow" (Central IL)
Haban Blade Cylinder Dims:
A while back somebody emailed me and asked for the angle cylinder dimensions on a 54" Haban Blade.
I couldn't find the email, so here are the answers:
Bore = ~2", Stroke = 7.5", Rod Dia. = 1", Closed pinpin = 14", extended pin-pin = 21.5"
A while back somebody emailed me and asked for the angle cylinder dimensions on a 54" Haban Blade.
I couldn't find the email, so here are the answers:
Bore = ~2", Stroke = 7.5", Rod Dia. = 1", Closed pinpin = 14", extended pin-pin = 21.5"
- Joined
- Aug 23, 2006
- Messages
- 2,912
- displayname
- Allen Schumacher
Ken P., just go over to the Sandbox and start a new thread with your ideas!
mhomrighausen
Well-known member
- Joined
- Sep 20, 2001
- Messages
- 3,133
- displayname
- Marlin Homrighausen
Charlie P. Really cool picture. Thank You for posting it.
David K. Nope.... You didn't blow up. Sometimes one just has to be very straight to the point. And on such a subject you are one gentleman that speaks with authority based on experience.
David K. Nope.... You didn't blow up. Sometimes one just has to be very straight to the point. And on such a subject you are one gentleman that speaks with authority based on experience.
jchamberlin
Well-known member
- Joined
- Jul 19, 2010
- Messages
- 1,842
- Location
- Farmville, North Carolina
- displayname
- Jeremiah Chamberlin
"You can't be serious," I thought.
I posted question about "Trunnions" in response to Donald Tanner's post. I checked the FAQa as Charlie recommended. I remember that you had to take the fender off.
But seriously!
After checking the Service Manual as per the FAQ posting, I learn that I have to drop the transmission. This can't be right! There must be a way of replacing the springs short of removing the transmission and re-welding the trunnion, etc.
All I want to do is put in new springs. I'll fix the trunnion next year or the year after when I break it all down.
I just got through replacing the driveshaft and flex couplings, removing all the spirol pins along the way.
Does anyone know a way of just slipping in some springs?
Help appreciated.
mgonitzke
Well-known member
Jeremiah-
All you've got to do is remove the snap ring that holds the cam plate on the trunion shaft; however, this is easier said than done.
Honestly though, replacing the springs isn't going to do much at this point, because it appears that both springs are intact. The major problem is the wear in the trunion slot, not the springs. It is not that big of a deal to pull the trans...just clean the outside, disconnect the hydraulic lines and driveshaft, remove the linkage and six bolts holding the rear to the frame, and roll it out with the rest of the tractor supported. Might as well replace the cork gasket and the brake puck O-ring while you are in there, too. A Hytran and filter change would be a good idea, too.
BTW, I don't know if it's just the pictures, but I'm not sure you've got the front rag joint assembled correctly. From the picture, it appears you've got the two bolts from the engine side of the coupler going through both flex discs and directly into the metal coupling that is pinned to the driveshaft. The engine coupling needs to attach to one pair of holes in the rag joint, and the driveshaft to the other. Once again, that may be the way you have it, but that isn't how it looks in the picture.
All you've got to do is remove the snap ring that holds the cam plate on the trunion shaft; however, this is easier said than done.
Honestly though, replacing the springs isn't going to do much at this point, because it appears that both springs are intact. The major problem is the wear in the trunion slot, not the springs. It is not that big of a deal to pull the trans...just clean the outside, disconnect the hydraulic lines and driveshaft, remove the linkage and six bolts holding the rear to the frame, and roll it out with the rest of the tractor supported. Might as well replace the cork gasket and the brake puck O-ring while you are in there, too. A Hytran and filter change would be a good idea, too.
BTW, I don't know if it's just the pictures, but I'm not sure you've got the front rag joint assembled correctly. From the picture, it appears you've got the two bolts from the engine side of the coupler going through both flex discs and directly into the metal coupling that is pinned to the driveshaft. The engine coupling needs to attach to one pair of holes in the rag joint, and the driveshaft to the other. Once again, that may be the way you have it, but that isn't how it looks in the picture.
jchamberlin
Well-known member
- Joined
- Jul 19, 2010
- Messages
- 1,842
- Location
- Farmville, North Carolina
- displayname
- Jeremiah Chamberlin
Matt: Again, thanks for the response. I'm glad I posted.
The rag joint at the front may be incorrect, I didn't have anything to guide me.
The shaft coupler is secured by two carriage bolts run through a stamped steel "flange" shown in the Parts Lookup exploded view of the drive line. The carriage bolts exit toward the rear and are secured by lock nuts.
The rag joint is fastened to the engine itself by means of two bolts which pass through both rag joints into the crank shaft of the motor. These bolts each have close fitting washers stolen from the MTD deck.
The only thing that worries me about this setup is that there is really nothing to keep the bolts that run into the engine from backing out. I'm using blue locktite, but its not really a good solution. I've also tried using bolts that are long enough to bottom out, but I don't like that either, since they don't really tighten up the rag joint.
Finally, the holes in the flex joint for the engine bolts are (1) located closer in to the center (as they need to be), and (2) are larger in diameter than they need to be for the bolts. I suppose they are larger to allow for the rubber to "fold over" when the bolts are tightened, but I'm not sure.
As an aside, the reason I have nothing to guide me is that the previous owner, when he installed the Briggs & Stratton 16 HP motor, modified the drive shaft and threw away the flange. He also experienced a drive shaft that "let loose" inside the tunnel and beat up the steering column pretty badly. See below.
The rag joint at the front may be incorrect, I didn't have anything to guide me.
The shaft coupler is secured by two carriage bolts run through a stamped steel "flange" shown in the Parts Lookup exploded view of the drive line. The carriage bolts exit toward the rear and are secured by lock nuts.
The rag joint is fastened to the engine itself by means of two bolts which pass through both rag joints into the crank shaft of the motor. These bolts each have close fitting washers stolen from the MTD deck.
The only thing that worries me about this setup is that there is really nothing to keep the bolts that run into the engine from backing out. I'm using blue locktite, but its not really a good solution. I've also tried using bolts that are long enough to bottom out, but I don't like that either, since they don't really tighten up the rag joint.
Finally, the holes in the flex joint for the engine bolts are (1) located closer in to the center (as they need to be), and (2) are larger in diameter than they need to be for the bolts. I suppose they are larger to allow for the rubber to "fold over" when the bolts are tightened, but I'm not sure.
As an aside, the reason I have nothing to guide me is that the previous owner, when he installed the Briggs & Stratton 16 HP motor, modified the drive shaft and threw away the flange. He also experienced a drive shaft that "let loose" inside the tunnel and beat up the steering column pretty badly. See below.
OK you gurus.
I have recently purchased a 782D. Yippie!
It runs well and has low hours. I have a few odd maintenance chores to catch up on but no big deal.
It came with 44" deck. I know it will fit a 50" deck. My big question is can I go any bigger deck size?
I do have a supersteer axle set I can install. On that point I think it steers better than any of my other cubs. (Wide and narrow frames)
Would it steer even better with the supersteer axle?
Thanks a bunch.
Dudley
I have recently purchased a 782D. Yippie!
It runs well and has low hours. I have a few odd maintenance chores to catch up on but no big deal.
It came with 44" deck. I know it will fit a 50" deck. My big question is can I go any bigger deck size?
I do have a supersteer axle set I can install. On that point I think it steers better than any of my other cubs. (Wide and narrow frames)
Would it steer even better with the supersteer axle?
Thanks a bunch.
Dudley
