Toobuilder
Well Known Member
IO-360 (200HP - Bendix) in the RV-8. Engine was misbehaving with a little intermittent misfire on a recent cross country, so I installed new plugs (gapped and Ohm checked) and removed the Pmags for a visual inspection and it is timed correctly. (jumper in, slightly retarded). Did a compression test and all are strong, as usual.
Test flight saw an improvement to its normal, turbine like smoothness.
Last cross country saw #4 cylinder a little cooler than usual - both EGT and CHT. Going to my normal LOP cruise, #4 continued its trend of acting too cool by being the last to peak by a LONG way. My first to peak was 100 LOP before #4 finally peaked. The "GAMI Spread" was probably .8 GPH. LOP ignition stress test was normal and smooth. Resetting all to ROP then LOP shows the issue is consistent and repeatable. Fuel flow is within the bounds of normal.
I have not accomplished a fuel flow test (the bottle method) yet, but that's my next course of action.
If the cylinder was acting lean, it would be easy to suspect a partly clogged injector, but #4 is strongly indicating a rich condition, isolated to this one cylinder. It's possible that the other 3 have junk in them and are all slightly lean, but this seems very unlikely.
Any thoughts before I dive into the bottle test?
Test flight saw an improvement to its normal, turbine like smoothness.
Last cross country saw #4 cylinder a little cooler than usual - both EGT and CHT. Going to my normal LOP cruise, #4 continued its trend of acting too cool by being the last to peak by a LONG way. My first to peak was 100 LOP before #4 finally peaked. The "GAMI Spread" was probably .8 GPH. LOP ignition stress test was normal and smooth. Resetting all to ROP then LOP shows the issue is consistent and repeatable. Fuel flow is within the bounds of normal.
I have not accomplished a fuel flow test (the bottle method) yet, but that's my next course of action.
If the cylinder was acting lean, it would be easy to suspect a partly clogged injector, but #4 is strongly indicating a rich condition, isolated to this one cylinder. It's possible that the other 3 have junk in them and are all slightly lean, but this seems very unlikely.
Any thoughts before I dive into the bottle test?
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