Almost from the start of the Tomcat project, Grumman was aware that the TF30-powered F-14A would be somewhat underpowered. On February 27, 1970, almost a year before the first flight of the F-14A, Grumman had suggested that a Tomcat derivative be built powered by the winner of the Advanced Technology Engine competition, the two contestants being the General Electric GE1/10 and the Pratt & Whitney JTF22.
The Navy wrote up an new requirement (which they named VAX-2) which would eventually lead to a new designation of F-14B being assigned. It was anticipated that the F-14B would have 40 percent better turning radius, 21 percent better sustained g-capability, and 80 percent greater radius of action. At this stage of the Tomcat project, the F-14A was considered only an interim type, pending the introduction of the definitive F-14B. It was also proposed that all existing F-14As would eventually be brought up to F-14B standard.
The winner of the engine contest was the Pratt & Whitney entry, which was later redesignated F401-P-400. This engine was a derivative of the JTF22 Advanced Technology Engine, which had also spawned the F100 turbofan that was used by both the McDonnell Douglas F-15 Eagle and the General Dynamics F-16 Fighting Falcon. The F401-P-400 offered 16,400 pounds of thrust dry and an afterburning thrust of 28,000 pounds.
The seventh Tomcat (BuNo 157986) was set aside to serve as the prototype. It flew for the first time on September 12, 1973 with one F401-P-400 engine and one TF30 engine. Later, the aircraft was equipped with two F401 engines. With the new engine, the thrust-to-weight ratio of the F-14B was raised to greater than unity, offering a much improved performance.
Original plans called for the F-14B to start rolling off the production line with the 67th production edition, with earlier F-14As being converted to F-14B configuration when sufficient numbers of F401s became available. However, the development of the F401 turbofan soon ran into serious trouble, and failed its initial flight rating tests. Since the F-14A had already encountered severe cost overruns, and since the Navy's budget had been severely cut back at the end of the Southeast Asia war, the Navy decided to stick with the TF30-powered F-14A, and plans for the production of the F-14B were abandoned in April of 1974.
Only 33 hours of flying time had been logged by the re-engined 157986. Following the cancellation of the F-14B, 157986 was put into storage. It was brought out of storage in 1981 for evaluation of the General Electric F101 DFE engine, paving the way for the development of the F-14A(Plus) and F-14D versions.