After an increasingly successful two year program, Ford and their partner Shelby American continued to campaign the GT40 in prototype endurance racing. The 1965 version of the GT40 proved itself capable and was primary opposition for Ferrari’s P2. For the new season, Ford concentrated on developing the Mark Two GT40 which would compete against Ferrari’s radically different 330 P3.

During the 1965 LeMans, Ford received much attention for two large-displacement GT40s entered in the race. These two cars were prepared by Kar Kraft, a subsidiary of Ford run by Roy Lunn. They chopped up the GT40 chassis to accept the 427 CID Galaxie engine. Unfortunately, development time on these cars was short and the decision to run them at Le Mans was unexpected.

The initial performance of the 427 GT40 was promising. The car could reach 210 mph down the Mulsanne straight and qualified almost ten seconds faster than any Ferrari. During the opening hours of the race, prototype GT40s were in the lead. Unfortunately transmission problems arose, retiring both cars. Afterwards, it was clear that the 427 GT40 would be the car to race and a more robust transmission was necessary to make the distance.

The 1965 car left many problems which Kar Kraft could not have reversed during their short development time. Although the car was basically the same as the Mark I it had several hundred additional pounds of reinforcing and a longer nose which interfered with aerodynamics. Even though these problems arose, it was decided that the relatively cheap, NASCAR-proven 427 would power the 1966 Mark Two GT40.

Upon knowing Ford was to use the 427, Shelby inquired to have Ford’s Engine and Foundry Division reduce the weight of the NASCAR V8. Aluminum heads with smaller valves and other refinements helped shed 50 lbs off the engine.

Other modifications to the engine included the conversion to dry-sump lubrication with the help of NASCAR oil coolers and the move to a single Holley 4-barrel carburetor. After all was done the engine produced 485 bhp which was below the 520 BHP NASCAR unit, and well below the 100hp per liter achieved by the competition.

Special attention was paid to the gearbox and differential to properly deliver the tremendous torque generated buy the engine. Kar Kraft used many resources and development time to ensure the transmission failures of 1965 would not repeat. Surprisingly, Kar Kraft did not incorporate ZF’s new 5-Speed into the car.

Most of the chassis and suspension work was carried out by Shelby American. They revised suspension points, and reinforced the chassis only were needed.

Since the Girling discs were already reaching their limits in the small block GT40s, it is no surprise they were having a hard time stopping the faster and heavier 427 cars. Since there was little room to enlarge the disc and ducting already cooled them at too high a rate, a new solution was needed. Phil Remington, Shebly’s chief engineer, designed a method to quickly change the discs during a race. The system comprised of a retainer which allowed rapid removal of the brake caliper to provide fast access to the discs. Since the life a disc was roughly 13 hours, during longer races discs swaps would be mandatory.

In 1966, the Mk.II began dominating the world famous 24 Hours of Le Mans race in France. With Henry Ford II himself in attendance at Le Mans, the Mk II GT40 provided Ford with the first overall Le Mans victory for an American manufacturer.

The Mk.II took Europe by surprise and beat Ferrari to finish 1-2-3 in the standings.