I recently installed a new Titan O-340 Stroker (9:1 CR) in my 9A.
I've noticed on run-up at 1700 RPM that when grounding left, then right magnetos, I now only see a ~20 RPM drop each side. The engine is making plenty of power and running really smoothly, and EGTs are behaving as expected (all EGTs climb when operating on only 1 mag). I'm just not used to such a low drop.
My previous O-320 with 7:1 pistons would drop 90-100 rpm when switching off a mag. There's no difference in magnetos - I simply swapped the Slick 4370 and 4371 mags from the old engine to the new one. Timing was spot on with both as well. I did buy new harnesses though, and I'm using REM37BY plugs that the O-340 shipped with instead of REM40E plugs on the previous engine.
Could the low mag drop simply be due to the higher compression ratio? Do the longer-nosed REM37BY plugs have anything to do with it?
I've noticed on run-up at 1700 RPM that when grounding left, then right magnetos, I now only see a ~20 RPM drop each side. The engine is making plenty of power and running really smoothly, and EGTs are behaving as expected (all EGTs climb when operating on only 1 mag). I'm just not used to such a low drop.
My previous O-320 with 7:1 pistons would drop 90-100 rpm when switching off a mag. There's no difference in magnetos - I simply swapped the Slick 4370 and 4371 mags from the old engine to the new one. Timing was spot on with both as well. I did buy new harnesses though, and I'm using REM37BY plugs that the O-340 shipped with instead of REM40E plugs on the previous engine.
Could the low mag drop simply be due to the higher compression ratio? Do the longer-nosed REM37BY plugs have anything to do with it?