IH Cub Cadet Pulling and Hot Rodding

[dkirk]

Kenny, thanks for the picture enlightenment. The nozzle air bleeds do not have to be altered, nor any other holes or passages in the Kohler carburetor. That is what's nice about the modification. The venturi is small enough that a good signal is still produced yet big enough to flow more air at higher speeds. Seems to be a good compromise all around.

 

[dmorrissette]

Don, I think I may need to tear down my k301 because I'm burning a substantual amount of oil. If I find that the cylinder has already been bored .030 over, and I'd need to go more to clean it up, is it possible? Would I be better off finding another block?

 

[twheaton]

Man, you guys are really cool with your knowledge and experience on these Kohler engines.Makes for very interesting reading for me.I don't know squat about them,I just ask lots of questions and then act on what seems right for me, which gets me to Dan M's question to Don. I had a 301 that 030 over wouldn't clean up.The machinist at NAPA had sleeved several Kohlers that had to be bored over 030 for the sleeve, the sleeve installed and then the sleeve bored to Standard and to the new rod and piston.That is what I had done and it has worked fine for over a year.Just a possible solution for you to get other input on.

 

[farmall gray]

David K,
A couple questions in regard to your carb mods.
I don't know if you read my earlier post or not.
I built a K301 similar to yours but I am planning on keeping it at 3600 rpms. Will boring the venturi to that size help on mine too? I know you
sometimes run yours a little higher. Also, do you
know what size the K321 carb is? I'm planning on building a K321 for another tractor. Would you bore it bigger too? I'm not running the K361 rod
and my tractors are workers, so I don't want to risk turning them any faster. I was wondering too,
if the K321 carb is bigger than the K241-K301 carb. If so, could the K321 carb be a bolt-on mod for the K301? I'm also curious how you chucked the carb in the lathe. Did you use a face plate?

 

[dkirk]

Todd, thanks for the good questions - I'll try and answer them as best I can. I did read your previous posts and glad to hear that your K301 runs strong and that it was worth the effort.

I think the .875 venturi mod will work well on your engine even though rpm's are held to 3600. The fact that you've done a port & polish job along with the Vogel cam means that more air is being moved through and trapped in the engine, hence the increased power output. The carburetor mod will add the finishing touch and should work great.

The K321 also uses the same #26 carburetor as the K301, therefore, no gain. The K321 would benefit even more by the venturi increase due to the extra 2 cubic inch displacement it has over the K301. I would recommend the modification for the K321 you are planning on hot rodding.

As for machining, you can make up a plug that aligns the throttle bore up to the center of the lathe face plate. Then screw the carb mounting flange to the face plate and machine venturi using a boring bar. Whole job takes less than 30 minutes. Could be done on a vertical mill as well using a rotary table.

Hope this helps.

 

[sblunier]

Dave, Todd,

From my experience, later model 14hp 149 engines run the #30 carb, not the #26 like the early 149's and 147's. So, you may already have the "big" carb on your 14hp, only way to check is to look for the # in the venturi or measure the bore. Of course that might not help keep the flow smooth in the base gasket area, as you probably will have a step on the 14hp with the big carb, but you may get the larger venturi by default.

Don't know about the carbs on a QL, but would assume that if they made a change late in the 149 run that they carried it into the QL series.

 

[farmall gray]

Dave, Steve,
Thanks. I should be getting the tractor soon. I'll
have to check out the carb when I get it. It will
probably need the throttle shaft bushing kit anyway. I guess if it has the #30 carb I'll just
port it to match the carb. BTW Dave, I did the JB weld thing on the intake port on my K301 too.

 

[dkirk]

Steve, thanks for the K321/carb size info. I'm just not experienced enough on the K321 to know that Kohler did a carb swap. I've only worked on an older K321. But if the newer engine's used the #30, they probably have an inlet port that matches the throttle bore. Don V. probably knows the answer to that one.

Todd, that JB Weld is good stuff. I've had the carb off my engine several times and no sign of the JB coming unglued.

 

[dvogt]

the 14 hp #30 is a 15/16 venturi , the #30 16 hp is 1 in. , I wouldn't go bigger with the venturi, I've found on the dyno if you start to go to big you start to lose torque , not a good thing. theres some engines we've run where we would gladly trade 2 hp for 1 ftlb of torque.also if you start to go to large as David said you lose the signal at the main jet. you then need to open that up to compensate for the lost signal. it don't need more gas , just a larger opening to draw the fuel through.


Dan M. you can go Timothy's route or get a used block that will clean up . I wouldn't worry to much . I'd have to say that 95% of kohler K series rebuilds clean up in .010.

 

[sblunier]

Don,

Thanks for the details...I know they are #30's, but didn't know a #30 came in two bores...The Kohler King strikes again with great and usefull information!!!!!

(It's been too long since we talked about carbs at dad's place, the details are long since forgotten

)

 

[nfisher]

Don,
after reading the information here and on David Kirk and Brian Miller's pages i decided to go a little better than stock on my 341 rebuild. the longer duration 361 cam is on order and i've been playing around with the intake a bit.

the head will be shaved at least .020, and some casting flash cleaned up here and there.
the results should be interesting.

thanks for the info you folks are making available here.
~ Nate

 

[dmorrissette]

Don & Timothy,
Thanks for the insight on possible solutions to an over .030 k301 cylinder. Once I pull it apart I'll know what I need to do. I'm looking to build it to stock or a bit better.

(Don)Ever dyno one of your comp k301 engines? What are they capable of with a stock bore?
Dan

 

[kweimann]

Don,
Looking at Nate's valve relieving had me thinking about lapping. I usually make the witness ring (contact land area) about .035, I do this by making a 3 angle valve seat with my Neway cutters. Is there any advantage of a narrower contact band? My NOS K341 shortblock appears to have new valves that were never lapped. I don't see any witness band at all on the valves. Was this a common practice at the factory? Maybe because both valves have rotators they figured they would wear in and seal after some run in?
Any thoughts?
Thanks for the great advice.
Kenny

 

[dvogt]

Dan , with our 30 cube motor which was a K301 12 hp we were hitting upper 40's for hp.

Kenny , I think the angles are most improtant. how you direct the air flow into the cyinder is critical even on a goverend engine. on a 14 hp stock engine we picked up 2.5 hp after getting the correct valve seat angles worked out. this engine had stock ports but did have the compression boosted & a K361 cam with timing alterations , We also ran advanced ign. timing. we were disapointed on our hp gains so we started playing on the flow bench with seat and valve angels. We also undercut the head of the valve to make it more of a nail head design . We then put all this into the engine on the dyno and we picked up a honest 2.5 hp. so the bottom line is you can do all the work you want but you do need to do your home work to get it right. we wound up drilling the emution tube out close to .025 larger to get enough fuel into it after all mods were done.

 

[nfisher]

Don,
since the 341 and 361 have identical bore and stroke, how much of the 2 hp difference could be attributed to the cam? i know the OHV contributes to the gain also... just wondering.

 

[bbell]

Don,
When switching a stock altered engine from gas to methanol should the ignition timing be bumped up? About where should the ignition timing for a stock altered on methanol be set?

 

[dvogt]

Nate . the engine's I've worked on had close to 5 hp in total gains, how much you'll get out of the cam depends on how well you manage the rest of the work on the engine such as ports , seat angles , timing ect.

Brian it depends on your head design & spark plug location. what works on one engine don't always work on others. but the 28-32 degree range is pretty common.

 

[dkirk]

Don, thanks for sharing the impressive power outputs on the K301. What rpm was the engine turning when developing the 40+ horsepower? Also would like to know what is the best horsepower @ rpm you've seen on gasoline with the 30 cubic inch engine?

 

[dvogt]

David , that was on a lky buring NQS 30 cube. come to think of it we dyno'd one for a guy last winter that hit low 50's with dual 1.200 carbs on it. We never ran a 30 on gas. only gas burners we've ever spent time on were 14 & 16 hps.

 

[nfisher]

Don,
you're right, without a flow bench it's tough to tell if what you're doing is helping or even harming performance. i did find an interesting link on how to build one but it doesn't look like i will be in the near future.
how to build a flowbench
i'll just have to be satisfied knowing the engine is "better than stock".