How many stock cranks have you broke on the dyno Don?

2 or 3. but the failure rate is pretty hi because we probably only ran 6 - 8 motors with stock cranks

Is that on S/A and larger engines? Or have you broke them on the stock stuff too?

I am ordering the last of my parts to rebuild my engine (K301). The last thing I need to order is the steel crank from Midwest. It will be balanced.

as Smokey Yunick used to say "when ever you build a motor stick the longest rod possible in it"
that said, there's big gains when you first start using longer rods, once the rod ratio falls within a certain range the gains are not as noticeable. your info is incorrect. a longer rod gives you more dwell time at TDC . during this time more pressure is built above the piston which gives more torque. if you hang a degree when on it you can see the extra degrees of dwell at TDC.
personally I don't think you would know the difference between the 2 . building a motor like you are and lack of a dyno it will be difficult to get the most out of it.
if its a 4000 rpm motor no pop out

broke 2 in stock 14's

OK. Finally got the parts together to rebuild the engine.
LP head
ZK #3 cam, lifters, springs
Steel crank, balanced.
14 lb starter pulley
steel governor gear
Bosch coil and copper plug wire.
11 ball main bearings

Do I need a 36 lb fly wheel and if I do, will the flywheel fit under the fan shroud? Will I be able to swap engines without changing the length of the driveshaft? The pulling engine will only be used for pulling. What about cooling? If I need a flywheel, which one do you recommend?

How many RPM do you plan on turning it? As for a cooling fan you can use the small 12v boat fan MWSC sells, bolt a plastic fan from a Command style flywheel on it or just go without.

4,000 rpm. I would like to run a steel flywheel with a plastic fan but could not figure out which fan and steel flywheel combination would fit under the engine tin.

I would think with the heavy front pulley a 25# flywheel would be enough. As for getting it to fit under the stock tin I imagine that is going to be trial and error. I don't use any type of cooling at all so I am not much help. But plastic cuts pretty easy.

I'd think about using the 8 ball mains

OK. I ordered the 15/17 gear set, a 13 tooth pinion, and a billet pinion carrier. My transmission has a heavy fine tooth carrier, not the 2 piece. I have a 2 piece carrier. When I get the transmission rebuilt, do I need to install the two piece carrier? The engine will have no more than 20 hp. Is there anything else I need to do to the transmission given 20 hp.?

in my opinion I'd put the 2 piece in. save the other for a second tractor. also weld and reinforce your 2-3 shift fork

The deal from Midwest includes a new 2-3 fork, so I am good there. Thanks

aftermarket or stock? if its a stock one it needs work.

Aftermarket.

I am thinking about buying some cut tires. Our local track is soft until you dig down about three inches, then it gets hard. What is the best tire to buy for hard or soft tracks for a 4000 rpm tractor with about 20 hp.?

What size and style are you required to use?

26x12 professional pulling tires. Vogel has too many choices. The track is definitely not a biting track. Usually very dusty, dry, and loose. Once you dig past that it is very hard.

there's allot of choices in tires. I don't believe any of them work decent "out of the box" . they all need cutting or hardening or both to get the most out of them. right now the Nichols Edge tires are about the best you can get if they are cut properly. before that the original Lawn Tec L or S tires were the hot ticket. the new Lawn Tecs show hope but when tested heads up to a Edge tire the Edge seams to preform better. I've not had much luck with Vogel tires. most guys that run them like the 08's or 11's if I was going run a Vogel tire I'd chose the Riot , its a radial tire that is a copy of the 11. We've been watching them pretty close and they seam like a nice tire. Vogel says the preform nice "out of the box" but you talk to real good tire cutters and they have their own opinions.
there's allot of things to keep in mind for tire cutting that most people don't think of. tire angle: anywhere fro 23 deg to 10 deg. snub nose tires; 2 inch snub to 3 in snub. lug front angle and side reliefs. and then you have the multi angle Edge. most people that run Edge tires run a 17 deg lug with side reliefs and they leave the compound angle part of the lug on.
I wish we had the money spent on tires that just didn't work or worked on only 1 type of track and the wasted cuts.
it would be interesting to hear others opinion's on this

Riots were on my short list because of the taller lug. Been eying the Nichols Edge too but not sure what cutting needs to be done.

If you buy Edge tires make sure you get the hard compound. the soft compound tire works better and are great on a controlled track. but most outdoor tracks are pretty hard and tend to have stones and stuff in them. the soft compound will chip bad. you may want to get Robert Nichols number if you go that way and talk to him about what you need. very smart tire cutter

Thanks. It looks like new tires will have to wait until next year. I talked to my engine builder and he has a 122 minus an engine that is set up to pull. Going to have my transmission parts and engine put into that tractor. I'll post pics when it is finished.

Here is a sneak peek at the new tractor. The engine is finished. The steel crank caused a number of clearance issues. It hit the cam shaft in several places and had to be ground and polished a bit to fit properly. I cannot believe the difference in weight between the steel and cast crank. The steel crank weighs 2 to 3 times as much as the cast crank.

The orange paint is just what they had available at the shop. I have decided to name it Crusher.

ever see how heavy a stock crank is after you balance it for a heavy rod? or a steel crank after you add a couple slugs of heavy metal to get it balanced for a 4 1/2 bore?
looking good. what diameter pipe is that for the exhaust ?

I believe it is 1.5 inches. Bought it from Lakota. They cut it too short near the exhaust flange so it had to be welded on.

1 1/2 is kind of big from what we found in testing. you'll probably find better torque with a smaller pipe. maybe around 1 1/8

Good to know. Thanks

The transmission is finished and the tractor is wired. Only thing left is to finish the weight bars.

looking good, you may want to consider getting a Kohler mechanical fuel pump for it or make sure your gas tank is always full.

Thanks. The builder has spent a good bit of time on this. Notice all the holes in the frame have been filled. The price for the body was just too good a deal to pass up.

Getting closer to being done.

Tractor's looking great!, thanks for the updates.

Tractor Porn
 

Well, I got the tractor back from the builder yesterday. Spent today adjusting the seat and stuff. AAAnd installing more stickers. Here are a few pics. The skull stickers came from Greece. Actually ordered a second set to make sure I have spares.

Today we had a test and tune. I had the chance to compare my 26" Firestone 23 Degrees against my AT101s. The track was damp and biting. The AT101s killed the Firestones by 10 feet in the same gear. There was a lot of interest in the AT101s after that. Disappointed me as the Firestones cost a lot more and looked like they would do better. They needed a higher gear.

The tractor did well. Gearing is too low. RPMs did not drop at all using a 13 tooth top gear and a 17 tooth high gear. I am adding 23% overdrive to bump high gear up to 19.5 tooth.

I will keep the Firestones for now. They might work better on a loose track. Next I will be trying a pair of Vogel TT26" against the AT101s.

cub
 

With that motor and setup you have you definitely have the need for speed! With similar tractors in our club we run 20-22 gears. Mike:biggrin2:

The Firestone's really need to be cut to perform well.

I agree with Stacey that the stones need to be cut but also you have to play with gearing with each tire and balance to really get a feel for each tire.

The first run with the Firestones was 125 feet. I upped the air pressure from 3 lbs to 7 lbs for the second run. The second try they went 140 feet so there is room for improvement. The AT101s went 150 feet on the first try with 7 lbs of air. Really surprised me.

I have been a bit skeptical about the 15/17 gear set up. With my engine, I tried a 23% overdrive. Too high. The 15/17 works just fine with a 13 tooth pinion and my setup. I can pull in 3rd gear on most tracks and 2nd on sticky tracks.

Bought some of the new Lawntechs from Midwest. They are 81.5 inches around so they fit under the fenders without mods. They beat a set of super lugs by almost 50 feet. Had a good day pulling.

Got a look today. The Lawntechs rubbed on the inside of the fender and the edge of the fender under load. Moved the fenders up an inch. Going to add another 1/4"to the wheel spacers.