Quote:
Originally Posted by colin1928
For Power =Carburetion+Compression+Cam(breathing)
equal and balanced proportions
|
The above is so true and so important that I quote it again here for emphasis. Power here means HP, which keeps you running at the desired speed. (Torque provides acceleration.)
You need a lot of power to overcome the wind resistance on a boxy Model A at 50 MPH, plus the power to climb the hill, plus power to overcome rolling resistance. It adds up fast.
The HC head will certainly help, as others have said.
In addition to cam for breathing (you don't say which you are running), you might also need slightly larger than stock intake valves to improve the breathing and to keep everything balanced.
It also depends on the steepness of the hills you are trying to climb at 50 MPH (as others have mentioned).
You don't say what rear gear ratio you are running. With a stock rear gear, you will only be turning about 1600 RPM at 50 MPH in OD with that OD ratio, and you are probably below the peak of the HP curve. You are kind of asking a lot out of that little engine at fairly low RPM with that much OD, unless the engine and chassis are specifically built for it.
Or go out of OD and you are turning about 2200 RPM and running right around the peak of the HP curve. But then you don't get the benefit of that fancy OD.
Keeping everything balanced is the key.