Did not try yet.

Because the metering system is working fine (I mean the valve closes and opens), fuel pump is giving a pressure, and as soon as the metering valve opens I see a fuel dripping of the main nozzle then I figured out there must be two possible reasons:

1. metering spring is to strong - very unlikely as this is original one not modified by anyone.
2. at the venturi there is no enough vacuum to suck the fuel of the metering chamber. This vacuum is the one that presses the spring and opens the valve. So the reason for not enough vacuum must be either not enough airflow to the engine (kind of unlikely) or intake disturbance by the prop wash. It is possible that prop wash is pushing the air into venturi creating pressure instead of expected vacuum, and then the metering valve never opens.

To fix the second possible issue I installed my ugly velocity stack. This additional 1 inch of tube in front of venturi should smooth out the air flow and fix any pressure wave problem. I'm going to run the engine soon.

The last mixture I made was 9% of Red-line synthetic oil, and it was plenty of oil inside the engine. Now I mixed next batch of fuel this time 1:16 (6% oil) with Amsoil 100. After I run a couple of tanks of that through this engine I will check it again. As long as I have heavy oil spill on the fuselage I think I am OK with lubrication.