GregP
Major
The height difference was solely because they went from a "long nose" Allison (as in a "C" series) to an "F" series.
C-Series below:
F-Series side view below:
Note the prop shaft in the top pic is below the cylinder heads and about in the middle of the cylinder heads in the F-series drawing. I doubt extremely seriously it was a desired propeller position change. Rather, it was a consequence of the different prop shaft locations in the F-series engine as opposed to the earlier nose case prop shaft position. The alternative would have been to lower the F-series engine the amount of the change, which was structurally and aerodynamically an unsound option without a major redesign, and the entire P-40 airplane came about by changing engines from a radial to an inline WITHOUT a major redesign, so a redesign to change prop shaft height was never going to be done.
C-Series below:
F-Series side view below:
Note the prop shaft in the top pic is below the cylinder heads and about in the middle of the cylinder heads in the F-series drawing. I doubt extremely seriously it was a desired propeller position change. Rather, it was a consequence of the different prop shaft locations in the F-series engine as opposed to the earlier nose case prop shaft position. The alternative would have been to lower the F-series engine the amount of the change, which was structurally and aerodynamically an unsound option without a major redesign, and the entire P-40 airplane came about by changing engines from a radial to an inline WITHOUT a major redesign, so a redesign to change prop shaft height was never going to be done.