1966 Pontiac six overhead cam !
I saw just one of these once,,they might be rare?
The new OHC-6 debuted for the 1966 model year, completely replacing the 215-cu.in. pushrod six offered in '64-'65. Displacing 230-cu.in. and generating 165hp in base one-barrel carburetor form with 9.0:1 compression, the new engine far outperformed the previous 140-horse pushrod engine. The big news, however, was the Sprint version, as found in the Tempest Sprint, which featured a Quadrajet carb, 10.5:1 compression, a hotter camshaft, and a "split" exhaust manifold with dual outlets, all contributing to its 215hp rating. For 1968, the OHC-6 received a displacement increase to 250-cu.in. (4.1 liters, up from 3.8), which resulted in a power increase on the base engine to 175hp while the Sprint version remained unchanged. For 1969, the Sprint engines coupled to manual transmissions were rated at 230hp, while automatic versions remained at 215; the difference was attributed to different camshaft profiles.
https://www.hemmings.com/stories/article/the-pontiac-overhead-cam-six
The overhead camshaft was driven by a fiberglass-reinforced “Gilmer” belt that was cogged and similar in design to the belts that drive superchargers. This was a major design deviation from previous overhead cam engines that drove the cams via gear sets and/ or chains. The 1-inch wide belt rode on large diameter cast-iron sprockets to help reduce bending fatigue on the belt and improve its life span. The major concern of the engineers was whether the belt would hold up to the day-to-day requirements of normal driving and provide an adequate service life. Early testing followed by a long service life validated the design and few if any belt failures were reported.
Pontiac's Fantastic Six