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The Lotus Twin Cam engine ( [link] and [link] ) was developed from the Ford 1498 cc 116E pre-crossflow engine block. Overbored and given a longer stroke crankshaft the capacity was raised to 1558 cc. Using twin Weber 40 DCOE carburetors ( [link] ) the Twin Cam model with 115 bhp in Special Equipment tune or as a Lotus-Holbay version 126 bhp ( [link] and [link] ). A summary of the specifications of the Special Equipment tune Twin Cam engine is given in [link] .
| Engine | Lotus Twin Cam | Ford Kent (1600 GT) |
| Displacement (cc) | 1558 | 1599 |
| Bore (mm) | 82.55 | 80.98 |
| Stroke (mm) | 72.74 | 77.62 |
| Compression ratio | 9.5:1 or 10.3:1 | 9.0:1 |
| Power (bhp) | 105 to 120 | 84 (110) |
| Torque (lbs/ft @ rpm) | 108 @ 4500 (113 @ 5500) | 91 @ 5500 (105.5 @ 4800) |
| Oil pressure | 35 - 40 | 35 - 40 |
| Valve clearances | In 0.005, Ex 0.009 | In 0.010, Ex 0.022 |
| Carburetor | Twin Weber 40 DCOE sidedraught | Single Weber 32DFM twin choke downdraught |
Ford introduced the 105E Kent engine in 1959 in a number of displacements: 997 cc, 1198 cc, 1340 cc, and 1500 cc. All of these early Kent engines had both inlet and exhaust valves on the same side of the head. In 1967 Ford redesigned the head as a crossflow unit creating the definitive 1300 cc and 1600 cc engines ( [link] ). In 1970 Ford further improved the block making it stronger and more suitable for tuning and racing applications. These blocks are designated by their “711M” numbering. As used in the Seven the 1600 cc engine was essentially that from the Ford Cortina GT and used a standard Ford intake manifold with a single Weber 32DFM twin choke downdraught carburetor ( [link] and [link] ). A summary of the specifications of the Cortina GT tune Ford crossflow Kent engine are given in [link] .
As with the S2 and S3 Seven, the Ford Mark 2 Cortina GT/Corsair 2000E gearbox was employed. More correctly known as the 2821E, it is a semi-close ratio 4-speed all synchromesh gearbox ( [link] ), with synchromesh on all forward gears. Since it was also used in the Lotus Elan it meant a commonality of supply for Lotus Cars and Lotus Components.
| Gear | Gear ratio |
| 1 | 2.97 : 1 |
| 2 | 2.01 : 1 |
| 3 | 1.40 : 1 |
| 4 | 1 : 1 |
| Reverse | 3.32 : 1 |
As fitted to the Seven (and Ford’s own Corsair and Cortina) the gearbox was used with a separate remote control assembly ( [link] ). The three-rail selector mechanism was later replaced by a single selector rail; however, since this requires modification to be used in the Seven it was not adopted.
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