The 170 I6 is the rarest factory engine — 1966 only. Almost every survivor has been swapped out. Treat it as a curiosity, not a build platform.
The 1966 Bronco shipped with an optional 170 cubic inch inline-six (2.8L), a derivative of the Falcon economy engine. Output was approximately 105 horsepower and 158 lb-ft of torque. It was paired with a 3-speed manual.
The 170 was replaced by the 200 I6 in 1967, itself a mild improvement. Neither is considered adequate for trail use with stock axle gearing. If you find a numbers-matching 170 car, keep it stock for value. If you find a running 170 in a driver, a 302 swap is a straightforward upgrade.
Key specs:
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.