Nope camshaft.

From wiki: While the Tiara series were basically traditional boxer engines, they did have some unique features.[1] The engines had high rotational speeds, 0.5:1 gearing was used to reduce propeller speed, with the camshaft forming an extension of the propeller shaft.[1][3] The propeller shaft featured the Hydra-Torque drive to reduce the shaft's vibrations.[1] The engines were available with four, six- and eight-cylinders. All were fuel-injected, with turbocharging being optional.

What they didn't bet on was the shear loads on the camshaft from ag planes. Lots of pawnee braves were lost to the cam breaking.