Hi,

I have a 3W75iUS which I need some advice for.
The engine at the moment has a brass tube soldered to the diaphragm cover and a piece of Tygon tube going into the fuz. I have now bought a velocity stack for the engine aswell as an airfilter to quieten induction raw as the carb is poking out of the cowel. Do I have to take the pipe from the diaphragm cover to the velocity stack now or do I leave it vented to the fuz. The velocity stack is the 3W one but does not have a nipple on it. I think I need to so that the pressure on the diaphragm is the same as the pressure in the inlet to the carb.

Any advice would be appreciated.

Cheers
Stuart.

The diaphragm is activated by atmospheric pressure, leave it in the fuselage..

Fly the engine like you have it and see how it performs. If its not performing, try plumbing the tube into the intake manifold and see what happens. Depending on how your fuselage is sealed up or if it has any openings could affect the air pressure inside the fuse. and affect the way the carb pumps fuel.

My .02 worth.
the tube was place on the cover and vented into the fuse to compensate for any positive or negative air flow in the cowled engine compartment. By vent ing into the fuse the theory is that the pressure will remain constant @ 14.7/15psi at sea level.
I think, no I'm sure.

Thanks for the replies guys. The fuse is not sealed as the box section that the engine is bolted to has no lid on it, so I guess the pressure could still change. I have flown the model with a velocity stack on it and the carb vented to the fuse and the engine fluffs when going to knife edge and inverted. This I think is due to the diaphragm pressure???