Norvel MigBig Stunt Setup
I have been very sucessful in using Norvel BigMig .049 engine for stunt. I found that this setup will give you an optimal run for the 6 minutes need to complete a AMA pattern. Do not use stock muffler presure setup that comes with the engine. The secret is uniflow vent.
Even a startup engine can be modified to accept the uniflow vent. This will the extend the lap count to 50+ with this tiny stock tank using 10% nitro. APC 4.7 X 4 prop and 38' lines.
Tank height is about the center line of the needle valve with the muffler. However, if you do not run it with the muffler, I found that the tank height may need to be raised another 1/8".
Note: Use a 1/8" slice from a medium silicon fuel tubing as a bushing for APC's props.