I thought you might find these curves interesting. They are from my new British 1400 motor, but with a distributor and standard 1200 motor carb & intake.

See how flat the power curve is, and how max power actually is at our max rpm of 3,600? Also see how the torque curve peak is at much lower rpm?

As I understand it, you need max torque on take-off, when the rpm are low, and max power at max speed, so it seems this motor is well-suited to our application.

The flat power curve also explains why my coarse, wide-bladed propeller does not spoil take-off performance although it makes my engine rev so much lower and is quieter during aerobatics.

Incidentally, this motor appears to produce 44 hp, rather more than my Australian motor's 41hp, but it is all understandable when you take into account that the Aussie dyno runs were made at 30 degrees C, while the Scottish ones were done at 10 degrees C. I guess that's 90F and 50F for the prehistoric dinasaurs out there.

Yours, Bob

What is the compression ratio of your new 1400cc engine. Also are you using 40hp 1:1 rocker arms or 1600 1:13 ratio arms?

Compression ratio is 8.2:1 and they're either 1.2 or 1.25 to 1 rockers, although I doubt if that makes any difference at all.

Yours, Bob