Chris Engler
Active Member
During a first start working with the local A&P we noted a couple of issues that have us stumped. The set up is as follows:
Airplane - RV-8
Engine - Superior XP-400
Prop - WW constant speed with HRT blades, 14 inch WW spinner
Governor: MT
Ignition System - Standard mags and G3i
Issue 1: Prop Not Moving:
We've run the engine for over a 1/2 hour at various RPMs including 2000-2500 and moved the prop pitch many times....sometimes slow, sometimes fast, and can not get the prop pitch to change. We pulled the governor, confirmed the gasket is oriented correctly and there are no visible blockages/obstructions. We also confirmed that the prop shaft plug is removed.
Issue 2: Engine Coughs/Dies at High RPM
When the throttle is advanced, all is well until around 2400 RPM then the engine will cough/sputter. If the mixture is leaned (about half travel on the throttle quadrant) I can keep the engine from running rough and at full throttle and half "lean" maintain around 2550 RPM.
All EGT/CHT readings are in the green, fuel pressure is 4.5 - 6 psi, and oil pressure is fine. Fuel flow is reading 30 gph at full throttle though the Red Cube has not yet been calibrated.
The coughing is present with the G3i ignition system switched both on and off so we don't believe that's a factor. Thought possibly the stock snorkel/air filter were not providing enough air volume (we assume the "cough" is due to a rich mixture since leaning eliminates it). To test that theory, we opened the alternate air supply to provide more inlet area but that had no effect...cough still there at 2550 RPM.
Planning to call Superior and WW tomorrow but wanted to put this out to the collective wisdom of the VAF community for thoughts/suggestions.
Thanks in advance!
Airplane - RV-8
Engine - Superior XP-400
Prop - WW constant speed with HRT blades, 14 inch WW spinner
Governor: MT
Ignition System - Standard mags and G3i
Issue 1: Prop Not Moving:
We've run the engine for over a 1/2 hour at various RPMs including 2000-2500 and moved the prop pitch many times....sometimes slow, sometimes fast, and can not get the prop pitch to change. We pulled the governor, confirmed the gasket is oriented correctly and there are no visible blockages/obstructions. We also confirmed that the prop shaft plug is removed.
Issue 2: Engine Coughs/Dies at High RPM
When the throttle is advanced, all is well until around 2400 RPM then the engine will cough/sputter. If the mixture is leaned (about half travel on the throttle quadrant) I can keep the engine from running rough and at full throttle and half "lean" maintain around 2550 RPM.
All EGT/CHT readings are in the green, fuel pressure is 4.5 - 6 psi, and oil pressure is fine. Fuel flow is reading 30 gph at full throttle though the Red Cube has not yet been calibrated.
The coughing is present with the G3i ignition system switched both on and off so we don't believe that's a factor. Thought possibly the stock snorkel/air filter were not providing enough air volume (we assume the "cough" is due to a rich mixture since leaning eliminates it). To test that theory, we opened the alternate air supply to provide more inlet area but that had no effect...cough still there at 2550 RPM.
Planning to call Superior and WW tomorrow but wanted to put this out to the collective wisdom of the VAF community for thoughts/suggestions.
Thanks in advance!