K341 Hot Rodding

[MTM350]

Hi guys, I'm a member on other forums and was referenced to you guys for your expertise. I have a 1977 Cub Cadet 1000 that I am beginning as my new project. The stock K241 runs but is tired. I have a spare 13 fin K341 short block from a JD 300 that is bored .030 over already that I am looking to build up for this. At this moment I am not planning on pulling it, but I want to build this motor up some just for the fun of it. Sort of like David Kirk's Killer Kohler.

Since you pulling guys have experience with this, I figured the pulling section would be the best place to ask. Since I am planning on running 4000 rpm, can I get away with using a rebalanced stock crankshaft or do I absolutely NEED to go with a forged crank? Same for flywheel; will it survive and be safe at 4000 rpm or do I need a billet one?

If I must use a billet flywheel, what do you guys recommend for cooling since this will get run for longer periods of time than short pulls. I've heard that plastic cooling fins can be bolted onto the flywheels. What engine do I need to source this from and will it fit in the engine shrouds?

Thanks,
Mason

[J-Mech]

What block is it? (There are 3 styles) Just because it's Kohler doesn't mean it will fit.

4000 RPM is unnecessary and for what your doing is a bad idea. Keep it at 3800. All other issues solved.

[Merk]

What are going to use the 1000? Play? Work?

Is the 16 horse power block a wide base block?

Does the block need bored?
I wouldn't bore the block any bigger than .030. The block needs to be sleeved if it needs bored more than .030.

I'm with J-Mech on the 3800 rpm being max rpm. The flywheel is the weak link.

[dvogtvpe]

get a good reground cam. do a good valve job. if you want to turn it faster you'll want a steel wheel. plastic fins off a M16 or M12 work well. I'd suggest a heavy rod from Kerber and balance the crank. He has good cams as well. if you want to get fancy Kerber has a piston with a shorter pin height so you can use a longer rod which he makes to, longer rod in a motor helps the torque as does flywheel weight. you can also lay with the cam - crank timing and ignition timing to get more torque. when you start to get over 35ft lbs of torque you're headed in the right direction.

[dvogtvpe]

also keep in mind with more power come the need for better driveline parts. clutch. rearend ect .... you always fine a new weak link unless you do it right from the start

[MTM350]

Thanks for all the quick responses, the block is a wide base block with the mounting ears on the sides. It originally had a deep dish style oil pan on it (Like the cub one with the oil sump). I think I had measured the width and it will fit even with the mounting ears not ground off. If it doesn't then I will cut them off. The .030 bore is good, no grooves or ridges in the bore and doesn't need to be bored again.

The 1000 will be used mostly for play, as I have 10 other tractors and all this cub has is the tiny 38" deck. In the future it may see a snow blower but that is pretty far out. It will mostly be used for cruising around shows, taking the trash to the road, and the occasional load of firewood. So if I keep it at 3800 rpm, I can use my stock cast crank still, and can get away with a stock flywheel or should I just get the billet one to be safe?

I also plan on putting the Kerber Gov 3 cam in it. Do you guy's recommend this cam? How is the power output on it and how does it idle? The head I will be using will be a milled stock head, and will also be using slightly stiffer valve springs. As for the driveline, when I put the built k341 in the cub, I will be building up my clutch some more. Probably 6 pin driver, and a red spring. How about the creeper; will that hold up or will that become a weak link?

Thanks for all the help guys

[J-Mech]

No need for a billet crank.

You really don't need stiffer springs for the RPM your going to run, but remember with the #3 cam you need the larger lifters.

If you use the tractor for any hard pulling the creeper would be a weak link, but for what you said your going to do with it, I seriously doubt you ever load it enough to be a problem.


Unless you plan to be plowing or pulling this Cub, you better just keep it a little calmer. All your going to do is spend dollars with no need for the gain.... and once you change one thing, you'll need to keep changing other things to get it to run right. I really think you will be disappointed unless you actually use the engine as it will be built to use..... at WOT under load. Nothing you listed as it's "chores" will even come close to powering out a stock 341, let alone a built one. It's your money....


Another note: Check the block and make sure you can bolt the pan on it. Some of the blocks had "reliefs" in them that make putting the CC pan on it not possible. I don't think that is the case with the block that Deere used... pretty sure it was the one that Wheel Horse and maybe Bolens used. Deere crank will not work with the CC clutch.

[dvogtvpe]

get yourself some nice stainless steel valves, they are pretty common for that engine because of the stock altered rules. might even find titanium. I know Super Cub has stainless. We have done some pretty extensive testing with the #3 cam. it really produces a fat torque band. for what you plan to do I'd put the #2 in. The 3 has 7 degrees advance ground in. you will probably have to put the ignition on a separate switch. that way you can get it cranking and turn the ignition on. if you don't it can be hard on starters.

[MTM350]

For right now, I'm just building this as a for fun project. I figured that since all I have is an old used short block, and a 1000 with a tired 10 hp I may as well build the bigger motor for it. And while I'm inside it, I may as well do it right and build it up some. Now I'm not going to go too crazy on it, but I do want to play around with it some.

The block is the one with the wide mounting ears on the side, but no reliefs on the bottom oil pan surface. It originally came from the factory with the same oil pan as used in the Cubs. About the crank not working with the clutch, is that the drive clutch or the PTO clutch?

So that being said, as of now I'm figuring: stock balanced crank, stock flywheel at 3600-3800 rpm, Carter 30 carb, welded cam (Kerber 2 or 3), wide lifters (if needed), new or stronger springs, stainless valves, port and polish, valve reliefs, short piston, long rod, cast iron governor gear, milled stock k341 head, and a cast iron oil pan. Anything else that I should look out for when building things up?

[dvogtvpe]

you could weld the head chamber up and reshape it , if you know what you're doing you can get some nice gains. rework the weights on the governor. bore the carb venturi , check the vacuum at the main jet and play with that a bit.