Ten-Sixty-Six Hawk 5cc engine

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Ten-Sixty-Six Products. 5cc Hawk.

The 5cc Hawk is the engine shown fitted to the MRC car in all adverts and the 1066 catalogue. It is loosely based on the earlier, ‘Westbury inspired’ Falcon design, with many parts being interchangeable. To add to the confusion slightly it is wrongly captioned as an Arrow in Mr Clanfords A-Z. The most obvious differences between the two engines are a separate screwed in Cast Iron barrel and the change to RRV induction. These changes required new set of dies for the crankcase as well as patterns and cores for the cylinder. The basic design was similar, but the crankcase was altered to accommodate the new separate barrel with a venturi boss being added to the rear face. The barrel was new, but relatively low tech, and to ease the casting and machining of the ports reverted to a separate transfer cover. A ground and honed cast iron piston ran directly in the iron cylinder. The front housing, CB assembly and head were all interchangeable with the Falcon.

Because of the restrictions on industry that existed at the time, the engine was initially only available for export, but by Nov 1948 was made ‘available to the home market’.

The Hawk was available in 2 versions, H/RC for cars and boats, H/A for planes. Both featured a simple trumpet shape venturi with a two-part spray bar screwed into an enlarged centre section. For aeroplane use, a clear plastic tank with an aluminium top was attached to the underside of the venturi using a small bracket and brass draw bolt. A long choke tube replaced the fuel nipple.

The H/A version intended for planes had a standard Falcon style crankshaft whilst the car and hydro model had a hardened and ground full circle version, specially designed to ‘improve the volumetric efficiency of the crankcase’. Westbury designed his engines with very low crankcase compression, as he reasoned that overcoming this compression reduced the power of the engines. How wrong could he be? The change from sideport to RRV induction and reduction in the crankcase volume must have increased power noticeably.

Adverts for the MRC car in the 1066 catalogue show a Hawk with a CL2 clutch fitted to the chassis, and this is probably where most of the engines were used. It is also interesting to note that the three-shoe clutch could not be fitted without redrilling the chassis and repositioning the engine. A further ‘design glitch’ meant that the pressed aluminium body could not be used with a 3/8" plug as fitted to the engine.

Contemporary evidence suggests that the Hawk was only in production for a year and then only available as a completed factory built motor at £6.10.00 (£6.50). For this reason the engine is not very common. Engine numbers started at 1000 with the highest so far noted being 1029. A few motors have been built from spare parts to add to the total but probably no more than 50 Hawks exist.

By coincidence the first production Hawk, serial# 1000, with a three-shoe clutch fitted was discovered not far from Worcester and offered for sale on eBay during 2005.

Right: Hawk serial #1000