"Medicine Man" 440 Build

[Ranger Rick]

Hi everyone, I'm starting a thread on getting my Attex running again. I'm starting with what I was told was once a Tomahawk. It's a '78 poly body model that got a JLO LR399/2 transplant. I ran it once briefly several years ago and couldn't get it started again. I recently found that it has very little compression in the cylinders. Now I have a Cuyuna model 440 on the way and can't wait to drop it in. However, I'm sure I'm going to need some help along the way.

Since the body doesn't match the 440 Thunderchief styling, I decided to make up another name for it. I kept with the Native American theme, and came up with "Medicine Man" because I am an EMT involved with search & rescue, and hope to make a way to carry medical equipment on it.

Here are "Before" pictures

Starboard side.JPGEngine, front & left.JPGLooking forward with pan.JPG

[jpswift1]

The JLO 400 and 440's used in the Chief and Thunderchiefs were 4 port engines. The Cuyuna 440 is a world of difference in performance compared to the 400 and 440 JLO. They all share the same bottom end, but the Cuyuna is a 5 port engine and it has 6 bolt heads, instead of 4 bolts on the JLO engines. I have a Cuyuna 440 (top end) on a JLO 400 bottom end (from an Attex Chief) in my 440 Thunderchief racer and it's FAST. It beat my stock 500 Superchief and it's pretty quick on the racetrack too. You might want to put a rollbar on your machine because it's going to a VERY quick machine when you get that Cuyuna in there. Put a 34 or 36mm Mikuni VM carburetor on it and you'll really move out with it. We'll be very happy to help you out with this swap. Here's a Cuyuna 440 on the dyno......as you can tell they really scream and make some really good power.

[Ranger Rick]

Wow, that's more of an improvement than I thought. Looks like I'm adding roll bar to my wish list. What do you think about a dual carb setup then? I would try it single first, based on your recommendation, especially since it seems the dual mount adapters aren't easy to find. However, I'm picking up a seized snowmobile this weekend for its Comet 102c, and it is supposed to have dual VM32 Mikunis on a 500cc Spirit, so if those adapters work or someone knows where I can get the right adapters, I'm inclined to try it before buying a fifth carb for my collection. Unless of course there is some reason it's not a good idea.

And I know what you all are thinking. "Did he say 500cc?" I already thought about using the 500 if I could get the engine freed (that was the original plan, owner says it's locked up just from sitting for a year, and 62 hp is tempting), but it is a Suzuki engine and I have a JLO mounting plate that probably won't work of course. The bigger problem is the fact it's free air cooled, with no fan, so I have a feeling that's a bad idea for a year round AATV, and rigging up an electric fan system might prove too awkward, if it'll even be enough. So I grabbed the 440 when I saw it. Good thing I did. Apparently I'll get almost as much out of it without the hassle.

Jpswift, are you running an impulse fuel pump or electric on your 440? I saw that member nitrogasm had meltdowns in his Rockwell 440 with the factory vacuum fuel pump, and then switched to electric, so I'm considering it.

[hydromike]

Hey Rick...

Running a free air in the machine is a no-no. You'll never get the airflow necessary for cooling the cylinders, even with an electric fan. The dual carb setups for the Cuyuna engines are a bit tough to come by, but a big 34 or 36 will really do more than you'll ever need if you plan on carrying anything in the machine. Give 'ol Zerkle a call to see if he has any of the adaptors laying around. Cuyuna & 2si Engine Parts and Diversified Power Equipment Retailer in Illinois The 440 has the ability to propel a light Attex to about 45-50mph without much hassle. Get a roll bar; a five point harness and another machine for the trails.

A stock Mikuni impulse pump is about the best bet for providing fuel. What "meltdown" did nitrogasm have? I looked around, but only ever saw one post from him. If a fuel pump fails to pump, the machine simply runs out of gas and shuts off.

[jpswift1]

I have a dual carb setup complete with the carburetors adapters and intake manifolds all set and ready to bolt onto a Cuyuna 440 if you're interested. It requires some more time to get it tuned properly than a single carb setup just so you're aware. I'm running the stock Mikuni pulse fuel pump and everything works just fine on mine. And like Mike said, a free air engine in an AATV, is something you certainly want to avoid.

[Ranger Rick]

Good to know my gut was right about the F/A engine. As far as the nitrogasm reference, he said he melted two pistons because the factory fuel pump could not keep up. It was in the comments under this picture of his Thunderchief

JP, I'll definitely keep your setup in mind, thanks for offering. Hopefully I'll know better what direction I'm going in when I see what I'm actually starting with once everything converges in the garage. Engine arrives Wednesday, sled Sunday, and various other pieces in between.