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- Sick_Cylinder
The Ford G7A Can Am car was based on the Spyder version of the Mark 4 (GT40), but inspired by Jim Hall's Chaparral design they fitted a large rear wing of dihedral design and a two speed power shift transmission with torque converter - from their Funny Car race programme. Despite having an alloy engine the car was grossly overweight at 1900 lbs.
The engine was truly remarkable and was named the "Calliope" - Ford wanted a large displacement engine (427 cubic inch, 7 litres), but without the extra bulk of overhead camshafts. The engine featured 3 valve heads (24 valves in total) and was a pushrod OHV design with two camshafts in the centre of the vee stacked one above the other - 3 valves per cylinder was the most that could be opertaed by this system. The engine was intended for use at Le Mans, but rule changes restricted Group 6 sports cars to 183 cubic inches (3 litres). There were no engine restrictions in Group 7 sports car racing (Can Am) therefore the Calliope engiine could be used in the G7A.
Above 427 "Calliope" 24 valve twin cam OHV aluminium alloy V8. Below one of two cylinder heads from the motor showing cast inlet for Hillborn style fuel injection and twin inlet and single exhaust per cylinder. Bottom triple valves with single spark plug per cylinder.
Unfortunately the cast alloy blocks were porous and the motors were very unreliable, frequently suffering from overheating. The project was unsuccessful because of lack of development and Fords budget cuts. The project was sold for one dollar to the Agapiou brothers who campaigned one car for Peter Revson (and many other drivers) in the 1969 and 1970 seasons. They simplified things by switching to a normal, straight wing, ditched the two speed for a conventional Hewland 5 speed transaxle and swapped the underdeveloped "Calliope" for a Boss 429 engine (later 496). Sadly the car only finished one race out of 15 entered (second place in the 200 miles of Fuji).
If Ford's virtually unlimited budgets had continued and Sports car rules had not changed we would have seen this fabulous engine used at Le Mans in a Ford MK5 and it might have gone on to be a success in Can Am, but probably in a car less over weight than the G7.
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