I recently managed to find a PDF copy of the Blenheim Mk.V pilot's notes on the internet (lots and lots of googling around).
It has the same engines as the Mk.IV we have in the sim so most of the stuff is directly applicable (main differences were cockpit and control layouts and that the Mk.V has a constant speed prop while our Mk.IV has a two-stage prop), plus it gives some good advice on carb heat use.
On another note, i noticed you set your mixture full forward in the video. That is actually the lean position (it's clearly marked with "weak" if you look at it), ie, it uses the same control convention as the Hurri and Spit. Unless the controls are somehow doubly reversed in the interface (now that would be something tough to spot
) you probably took off with full lean mixture, that might a lot to do with why you can't apply full throttle: leaner mixture makes the engines run hotter.
Carb heat on the other hand lowers the density of air in the carbs so it's like flying with too rich a mixture.
I've copied the relevant parts from the Blenheim Mk.V pilot's notes that can be used on our Mk.IV in this thread:
http://forum.1cpublishing.eu/showthread.php?t=23192