Production of the 351 Windsor V8 engine began for the 1969 model year in the Windsor Engine Plant #1. Ford sales and marketing forecast that the demand for this engine would exceed the plant's production capability, and it was decided the additional production would begin at the Cleveland engine plant. At this time, it was also decided to upgrade the design of the new Cleveland manufactured 351s to a higher-specification power plant. It was decided that a new cylinder head design was needed for improved performance. Two cylinder-head designs were developed. One cylinder head used the same basic design as the 351W, but with larger ports and valves. The second had very large ports with canted intake and exhaust valves, similar to the Ford 385 Series V8. Sales, marketing, and product planning favored the canted valve design, as it was viewed as more innovative.