Injector Index Pin

A diamond-shaped injector index pin.

It was necessary to install the F-1 injector on the thrust chamber in a particular orientation. Two index pins, one round and one diamond-shaped, were used to ensure this orientation of the LOX dome and injector.

Although the ends of one of the index pins were diamond-shaped, the center of the pin was round.

In addition to being differently-shaped, it appears that the round index pin had a slightly smaller diameter than the diamond-shaped index pin.

The round part of the shaft would be positioned in the injector's index hole.