HI

I have a problem you guys might be able to help with!!!!! I have Zenoha G38 in a 1/3 G.P. Pitts Special it starts on runs great with the cowl off the plane and max's out at 7600 rpm with a 18x8 prop and pulls the plane nicely through the air. But when i install the cowl I loose about 500 rpm and it has a tendency to want to die when the plane hit take off speed. this is what i have donne so far


I have opened the cowl up right in from of the carb wich made it it better during take off ( it dosent want to die on take off any more) But still not getting top end power

I tryed a valosity stack and it has made no diffrence

i have baffled the entrance to the cowle and it has not fixed it iether

some has mentioned to me it might be a presure problem in the cowl???????? i dont know how to address that if that is the case i have about 4 time the exit of air as in take


any ideas would be helpfull



Thanks

I think you may need to solder a fitting onto the vent hole on carb. Then run a line from the fitting to inside your fuse. It will help the problem of differant air pressures in cowl. Hope that helps. Capt,n

I have a G45 in the same airplane. The velocity stack is on the right hand side, and when I do knife edges with the left wing down, it runs badly. This is because the cowl "shadows" the veolcity stack from normal air flow. So yeah, I agree that it's something about your intake to the carb. (Not a cooling problem)

Here is a picture of a Brillelli 50, which has the atmosperic pressure 'hole' in the carb plate modified with a standard pressure nipple. You connect some fuel line to this nipple, and run it into your fuse where the pressure remains more constant. The hole in your carb is likely along the outer edge of the ring on that plate, as opposed to the center like this one, but the same thing applies.

I agree with post #2 & 4. Just hope there is not a plastic based primer bulb installed on the carb as the vent on them is a pain to fix.