Tudor Built a Better Rolex Daytona—and Everyone Forgot

The Tudor Big Block 79170 may be one of the most important vintage Tudor chronographs—and the forgotten watch that beat Rolex at its own game.

Officially known as the Tudor Oysterdate Chronograph, the “Big Block” became part of Tudor’s first automatic chronograph family in 1976, more than a decade before Rolex introduced the automatic Daytona. This later reference 79170 combines a modified Valjoux 7750 movement with a date complication, screw-down pushers, an acrylic crystal and a bidirectional 12-hour bezel capable of tracking a second time zone.

In this Tudor Big Block review, I explore the history and specifications of reference 79170, its relationship with the Rolex Daytona and why this wasn’t simply a cheaper Rolex chronograph. In several meaningful ways, the Tudor was the more practical and versatile everyday watch.

We also look at the Rolex-signed components found on period examples, the strengths and weaknesses of the Valjoux 7750, how the substantial Big Block case wears, what collectors should inspect before buying one and why this reference represents everything Tudor was originally supposed to be.