The best read for lightweights that I?ve come across is in Phillip Porter?s ?E-Type ? The Definitive History?, the giant 700 page work.
Chapter Eight describes the Competition Cars 1962 ? 1964 in 110 pages, with the lightweight just being part of the evolution of that story. You really need the context of the development of competition E Types from the earliest production models to see how the lightweight ?evolved?. As with all competition cars, the specification was amended from one race to the next, and varied from one type of racing to another. The lightweight was ?just? another step in this evolution, and each car was different.
If you are building a semi-lightweight, this is a great place to start. It describes how the competition Es moved from all steel all glass to aluminium bonnets, plastic windows, aluminium tubs, together with the need to strengthen things up as their quest to make the E as light as Enzo?s car caused all sorts of structural challenges in racing conditions. Moving from Webers to mechanical fuel injection, from iron to aluminium blocks, and the introduction of the lightweight Dunlop callipers / D Type wheels all played a part in the evolution, and the latest spec wasn?t always the best for all types of racing.
Once you have all that lot sorted, then call up Lynx in the UK who produce a ?lightweight replica? and, as a potential customer, request a full specification of their creation, asking what options are available. They?ve made a few of these, and restored several of the original cars, so probably have some of the most knowledgeable guys available who can help. In talking through their options, you should be able to determine what sort of spec you want, depending on whether you want to build a fast road car, and endurance racer or an out and out circuit screamer. You should, after gathering all the information, have a good idea of the sort of specification that is available, and at what cost.
Budget may play a part here as well!! You can buy an aluminium tub, bonnet, doors and boot and an aluminium block. You can get all the rose-jointed suspension and the Dunlop wheels?not sure about the original callipers though?..doubtful. You can certainly get the close-ratio gearsets, but you may struggle to find an original ZF box! And I?d have a set of Weber 45 DCOE type 2s over the mechanical fuel injection every time?. They?re a darned sight cheaper and more reliable and just make the car sound right.
Get the book and get reading!
http://www.lynxmotors.co.uk/etype.htm