01-05-2020, 04:18 PM
Geoff Harrison is correct the Peter Ross book gives great detail of the modifications in the book "Lotus The early Years" It also shows the earlier block with the circular ports (8 0f them) and the manifold on page 44. It also gives a description of its production. I do have a copy; but copyright from 2004 is still in place so I can't illustrate here.