After the initial design was finished, outside consultant Richard Ansdale produced detailed drawings of the new cylinder head. Lotus employee Steve Sanville headed the production engineering team that included Mike Costin, Neil Francis and Bob Dance. Harry Weslake conducted a flow bench analysis on the early head. Early Twin Cam prototypes had problems at the head joint. Keith Duckworth, who had already left Lotus for Cosworth Engineering, was brought back to look at the new cylinder head. Duckworth made several design changes, reshaping the ports and adding structure to the head.