Sorry for continuing with the stupid questions but progress is reaaaaly slow

Solved the problem of the engine startup, it was because I flying with little fuel in order to ensure take off but both fuel cocks' first setting was switching to the (empty) outer tanks...
OK, first problem solved, second was quick to come:
In front of me at the cockpit I see the Oil Temp gauges.
I have to wait for the oil temp to reach 60°C in order to have proper rpm response from the motors (otherwise the rpm needles tend to "yo-yo" up and down).
where is the engine temperature (air cooled engine) Does it play any role?
What is the RPM limit for the engines?
My problem is that after takeoff, I get very quickly a grosvenor failure and afterwards things take their downturn...
~S~