I had the same setup on my last Ercoupe and had the same problem. I sent the horizon to the shop three times before I finally got the attention of someone there that understood venturi systems. He told me that the 3.5 inch instruments require more volume of air the the old 5 inch ones. I was getting plenty of vacuum but not enough volume to run both instruments. I discussed this with him and our region 13 tech guy and was told that if I moved the venturi to the passenger side I would probably get enough volume to run them both. I elected to remove the horizon since I didn't look at it enough to justify drilling new holes in the side of the plane. I had an electric turn and bank that gave me wings level info and that was sufficient for me and this is what I have in the present Ercoupe..
Kevin --- In [email protected], "Randy Hougham" <[EMAIL PROTECTED]> wrote: > > I have a DG and an attitude indicator on the same venturi. It's the biggest > Wag-Aero venturi that is supposed to run 3 instruments. In flight my vacuum > gauge usually shows 2 1/2 to 4" of mercury. Sometimes, the attitude > indicator will act strangely, rolling over or doing other odd things. The DG > is always working fine. I'm trying to figure out what the problem might be. > > My venturi is mounted on the pilot side, just aft of the engine cowling, on > the part of the fuselage that is angled as it widens for the cockpit. So the > venturi is parallel to the fuselage, but not pointing straight ahead. Could > this be a problem? Where do most people mount a venturi on an Ercoupe? This > set up has been on my plane since I got it, and I'm not sure that it ever > worked 100% all the time. Before I send my attitude indicator in for a > re-build, I'd like to figure out what the problem might be. > > If any one can help, I'd appreciate it. > Randy Hougham > Grandpa's Ercoupe > NC87384 >
