This is a fine page out of it that shows the harmonic resonances and the deflection of the crank. Note particularly well how the snout deflects radially! If you ever wondered why high performance 4 cylinder, high reving engines fractured their crank mounted oil pumps when run without a suitable crank damper, you need wonder no more...
This page gives you a handle on the resonant frequencies involved:
Thats all for now...
BigMoose