I normally only have cowl flaps open on Japanese open less than pos.4 (norm closed or pos.2). I only open cowlflaps/rad more than this if engine is near overheat.
Also you can use mixture of 101 - 120% to help cool engine at low to mid-high power and below mid altitude; say 2500m alt - well you can seriously over-richen the mix at high alt, enough to drown your engine and stall/damage it, will only run at lower revs or weaken mix; till running, and prop should be set initally higher say by 10% if revs arevery low.
I could be completely wrong, it's been a number of months since I flew Campaigns; I've only ever flown ingame as IJAAF/IJNAF, Luftwaffe & Soviet since 02', with the exception of Dofats? (thats the sound that jumps in my brain when I think who made it..) USN carrier & dead-reckoning nav' training campagin, also I fly using KB and a Saitek dual analogue 12button gamepad.
I'd say for 1750m - 3000m, somewhere between these settings might help you...
mixture 100% - 70% (unless mix is on slider, default is only in steps of 10%!)
Prop if not Auto 85% - 45% speed & rev limit dependant...]
DB engined prop range is 65% (max) to 20% - do not switch to Manual Prop (starts usually from 100% prop when changed) above 55% Throttle, or your engine will quickly overheat and maybe die from overspeeding.
Throttle 110% - 80% my normal no-enemy cruising is 70%
For 4.11m, reduce max normal throttle range 40% - 80%, cruising 65%.
Cowl/rad fully open for take off until 1000m (even after post take-off reduction of throttle at 300m) normally at
pos.2 or pos.0/closed-auto at alts' above 2000m.
For 4.11m, similar, but with operation specific to A/C type and trying to control operating temperatures encountered during flight within limits.
Supercharger 2nd gear switch for Japanese generally above 1150m
When going lower than 1200m switch to back down to 1st stage setting.
During diving too lower charge to help lessen overspeeding with lowering prop pitch with speed increase and efficient revs if you want to accelerate but be smooth on pullout.
Remember to set prop & engine reqiured to climb/fight/cut back etc before/during pull out, you could always use occasional combat flaps to aid lift, at higher energy bleed cost.