Re: Adjusting Speedometer
I can tell you that making the hole bigger doesn't change a thing. I already tried that years ago. But go ahead, it won't hurt anything either.
The reason is that the speedometer is nothing more than a pressure guage reading pounds per square inch. The pounds per square inch at the pitot will not change by increasing hole size. Yes, there will be more pounds, but there is also more square inches. So pounds per stays the same. You could have that hole 6 inches in diameter and it would still be the same per square inch. Pounds per square inch is a result of speed through the water, no matter how you read it.
That pounds per square inch is applied to a bourdin tube in the speedometer which converts it to rotation of the needle reading MPH. If there would be any adjustment at all it would have to be within the guage mechanicals.
