So, I am running on the ground an O-320 that has been pickled for about 10 years. I have installed it on my RV-9. It has a decent idle smoothness. It has decent mag drops at all rpm ranges. I have unhooked the fuel primer line to eliminate that fuel source.
So far I have not spent any money on it.
When experimenting with different throttle RPM settings above 900rpm, the engine is rough until given major leaning (I'd say about an inch and a half of mixture knob movement) at which point the engine smooths out and I gain about 200rpm. At wide open it is closer to 250rpm.
I have not had the carburetor apart yet (Marvel schebler MA-4SPA) so that will be my next step. For the experienced out there, is this a classic Marvel case? I am also aware of marvels float problems and updates. I am comfortable with working on carburetors.
My best leaned WOT so far is 2150 rpm. Hopefully that will improve with work.
Any comments or similar stories will be appreciated. Thanks