by A. Wayne Ferens
Images Courtesy of Ford Motor Company Archives and Ferens Collection
Published 4.30.2025
In its 40-year run, Ford produced the light weight small-block in 221, 255, 260, 289, 302 and 351 cubic inches. (Ford Motor Company Archives)
As the 1960s approached, it became apparent to Ford Motor Company that consumer demand was shifting to smaller economical mid-size cars and smaller, lighter six cylinder and eight cylinder engines would be needed to power them.
The new Ford 90-degree OHV pushrod cast iron small-block was introduced in July 1961 as a successor to the Ford Y-block engine. It displaced 221 cubic inches (3.6L) and was light-weight using thin wall casting for a short-skirt block that does not extend below the centerline of the crankshaft. Ford called it the "Challenger V8" and manufactured it in Cleveland, Ohio and Windsor, Canada in various displacements and horsepower ratings until 2001.
Ford kicked off their "Total Performance" campaign to promote its new line of cars and sell their new performance image to the "baby boomer" generation, who were getting their first driver’s licenses in droves. Ford decided to participate in a full range of competitive events to attract these potential buyers into the showroom. Henry Ford II got the word out that the company would not only participate in the Indianapolis 500 in 1963, but was serious about competing in international motorsports as well. The Advanced Engine Department of Ford's Engine and Foundry Division (E&F), under the direction of Bill Gay and Design Engineer Joe Macura, was eager for the challenge.
With less than a year to meet the objectives placed on E&F to compete at the Indy 500, there wasn't time to develop a new high-performance engine that was light weight, durable and capable of producing close to 400 horsepower. After performance and durability was thoroughly analyzed for a competition engine, it was decided the new 260 cu in Fairlane production engine would be most suited to meet the Indianapolis displacement limit of 4.2 liters or 256.284 cubic inches. Construction of an all-new rear mounted engine chassis was the responsibility of Lotus Cars in England under the direction of Colin Chapman.
A highly modified 260 production engine was assembled 'presto' for testing using both carburation and fuel injection. Modified cylinder heads and valve train revisions with improved intake and exhaust ports were incorporated, along with revised combustion chambers with domed pistons providing a 12.5:1 compression ratio. On the dynamometer, the modified 260 engine easily surpassed the objective of 325 hp on high-octane 103.5R gasoline. Other exotic fuels were also tested but rejected.
An aluminum version of the 260 engine was cast and tested as well. Two problems were indicated on both the dyno and in car tests showing head gasket problems and valve train limitations. Designing a high speed, high horsepower engine involves complex analysis for design and modifications, especially to an existing production engine. To achieve twice the power and a 25-30 percent weight reduction from the mass-produced 260 required changes and a redesign to most major components.
Major design modifications were as follows:
The aluminum version weighed in at just 357 lbs. and produced 376 hp @ 7200 rpm & maximum torque of 299 lb/ft @ 5200 rpm. The E&F Dynamometer Durability and Reliability Program was very encouraging and the engine was ready for vehicle installation and testing by March 1963. About 15 engines were produced. (Ferens Collection)
The "Engine That Could' was first installed in the Lotus 29 monocoque chassis in England. Early testing was conducted by racer Jim Clark at Snetterton in the UK. Note the massive Italian-made Colotti T-37 trans/axle that would be modified for the Indy race. (Ferens Collection)
Two Ford V8-powered rear-engine Lotus 29 cars were entered for the 47th running of the Indy 500. Jim Clark finished second with a qualifying speed of 149.75 mph. Dan Gurney finished seventh with a qualifying speed of 149.019 mph. Ford was very encouraged by the results, and development of an all-new E&F DOHC fuel injected aluminum V8 engine for 1964 would evolve from the 1963 pushrod engine.
The two Indy Ford-powered Lotus 29 cars were also entered in the August 18, 1963 Milwaukee 200 race, where they placed first and third. Clark’s margin of victory was a substantial 31 seconds. Ford, Lotus, Jim Clark and Dan Gurney were among the first who started the rear engine revolution that is still used to this day. (Ferens Collection)
But that's not the end of the story for the Challenger V8 race Engine That Could. Ford made a deal with Lola cars in the UK to help develop a new GT sports car that was already taking shape in Dearborn. Only this time, the technical challenges were much greater -- particularly starting from scratch. In 1963, the cars competing on the circuits at Spa, Nurburg Ring, Le Mans, Daytona, Sebring and the Targa Florio were capable of hitting speeds of 200+ mph. To build a car that meets FIA requirements, while maintaining high stable speed under varied conditions for as long as 24 hours with the ultimate goal to win, seemed almost impossible.
An early design of the GT concept is shown from June 1963 at Ford styling in Dearborn. The new car is 40.5 inches high, with an overall length of 159 inches, and a wheelbase of 95 inches. It will be capable of speeds of 200 mph. (Ford Motor Company Archives)
Having arrived at a basic configuration and initial shape of the GT car, other areas of concern and analysis had to be considered. Again, to have a car ready to test and race in less than a year, much had to be done.
The following areas of consideration to be used in the construction of the car were either supplied by Ford or outsourced: engine; transaxle; driveshafts; body; aerodynamics; suspension; steering; brakes; wheels; tires; interior/driver environment; fuel; and lubrication system.
E&F Division in Dearborn had a small supply of the Challenger 4.2 liter (256 cu in) aluminum pushrod V8s left over from the 1963 Indy program. The new DOHC Indianapolis engine being developed for the 1964 event was still being tested, so GT team manager Roy Lunn & engineer Joe Macura decided that the existing 1963 race engine could be converted rather quickly to long-distance road racing with some detuning to run on commercial pump fuel. Other modifications to make the engine road race ready were the following:
A shipment of six engines were sent to Ford's Yeovil Road works in Slough, UK. Abbey Panels in Coventry supplied the first GT chassis GT/101 on March 16, 1964, and the car was completed, including the installation of the Challenger Indy 4.2L V8, and announced to the press at a launch near Heathrow Airport in London on April 1, 1964.
The Ford push rod Indy 4.2L aluminum 350 hp V8 with the Colotti T37 4-speed trans/axle as installed in GT/101 in March 1964. The next three chassis GT/102, GT/103 and GT/104 were assembled using this engine. (Ferens Collection)
With improved performance from the new production 289 cu in version introduced and made available in late 1963, Ford decided that, when modified for road racing, it would be suitable to replace the more expensive all aluminum Indy version. The first modified 'Cobra version' of the 289 was installed in GT/105 in June 1964 and competed at the Reims 12-Hour Race on July 4/5 1964. Ford never raced the 4.2L again ...
Bibliography:
Classic Cars Magazine, March 1986.
Lunn, R.C. “Ford GT Sports Car.” 1967.
Sports Car Graphic, July 1963.
Gay, William. “Ford Engine For Indy Competition.” 1964.
