Dumas Drag N' Fly Hydros (20,40,60 sizes)

[carlnoki]

set the draw bar as close to being 90 degrees to the air flow coming into the carb.

and and with the slide plate closed, so should the v grove on the draw bar.

If you go ahead and do the v grove and hope diameter mods on the carb,

DO NOT USE A PERRY REGULATING PUMP!!!!!!!!!!!!!!!

it sends too much fuel for the modified carb to handle (meter) properly.

If you do NOT do the carb mods, then you can use the perry

regulating pump. You will have to adjust the pump using the

adjusting bolt at the end of the pump for proper flow.

That will all depend on the % nitro you use.

If you do not use the carb mods., the Dynamix carb is one of the best

and most linear carbs you will ever have the pleasure of using.

If you do or do not do the carb mods, the initial setting on the draw bar should be

mostly sentered (the actual round hole on the draw bar) in the carb throat.

then you can fiddle around with the idle setting for best results on the low end.

just remember on the Dynamix, the low end really has an effect on the to pend setting.

Best thing to do is get the motor running on the top end real good, richen the high speed

needle about 3-4 clicks rich, then start adjusting the low end till it starts to

affect the high end, then adjust the high end accrdingly, then go back to the low speed

and adjust it a bit more.

It is a ballancing act to say the least, but the end results are more than worth it.

I hope this has helped you out and has made sence to you.

If you have any further questions, give me a call this evening around 7PM eastern time

703--492--7337

Carl

 

[jetpack]

I think you covered everything I had a question about plus more. I'll keep your number in my carb box for sure on these. Thanks for the tuning procedure. That would have me chasing around if I didn't know the insights you gave. Mystery solved on the spraybar question, thats a good start. I can finish them up now. I had them all torn down to clean and polish. The steel throttle plates were all cleaned up with flat wet sanding then hand lapped to the carb body and cover for a nice ride. Butter smooth now with a good seal. Only thing I can knock about the carb is it would be nice if there was some type of fork seal (lip seal) for the spraybar exit. I can see that loosing fuel on some that are used, especially when snapping it open because of it having a store of fuel in it. I'm thinking possibly a small piece of heat shrink might help.

 

[Tom Foley]

I got a better idea .....trash that carb abomination and fit an old OPS or similar carb , to that thing . There are so many simpler better carbs laying around everyones shops !

 

[jetpack]

No Way! Simple is for Riggers!

Don't even touch the air that sits around the Dynamix! Stop playing with the needles, back away and nobody has to get hurt! Can't have it, Tom.

Is my little carb alright???

....yesssssssss.....

 

[harvknox]

Ive got a Dragonfly 20 kit and i think that for it to be legal to run in sport 20,per NAMBA rules, id have to stretch it out a coupla inches, but it would still be perfectly legal to run in 20 hydro..though it would get smoked! Also, i would think that with todays modern powerful engines and the spade bows on these boats, you might have a hard time keepin em on the water! Not tryin to discourage you as they are cool old boats...I thought about buildin mine and sticking a brand new old style K&B 3.5 IB that i have along with my first radio...a 1979 2 stick brown box Futaba with S-7 servos that still works as good as the day i got it! How many of you old folks remember that rig??

I had one of those. How many ran a model boat using a reed radio system? We're talking 1965 here, folks.

I raced a DragN'Fli 40 in 40 Hydro and a DragN'Fli 60 in 60 Hydro back in the late 60s/early 70s. Had a K&B 40 Torpedo in the 40 boat and a Rossi 60 in the bigger boat. The guy who designed the DragN'Flies, Frank Ward, lived in Seattle. He also designed the Wardcraft Deep Vees. Ah, back in the day.

JD

Jerry,don't feel like the Lone Ranger,I have two Orbit 10 channel vacumn tube transmitters with transistor receivers and Bonner Transmite servos.I also have a 10 channel F&M reed setup.I used the Orbit in an Ohlson&Rice

powered White Heat.I also have a single channel radio operating a rubber band powered escapement in a 21" electric powered cabin cruiser.The transmitter sits on the ground and has a 9'vertical antenna.A few years ago I installed a JR PCM radio in the White Heat and still run the boat on occasion.The boat has an Octura megaphone exhaust and can be heard in the entire county when it runs.I've talked about having a vintage event at some of our races ,but there is never enough time.

Harvey Liberman

Knoxville,Tn