Paul Dean Fife United Kingdom On 21 July 2015, Paul Dean Fife in the UK wrote:
"I thought of a non standard variable pitch fan for MGAs. I bought it new in the early 70s from some accessory shop. The idea with this was to reduce drag and improve mph and or increase power. It has 4 rather than 6 blades that are about the standard angle when still, but when revs increase the spring loaded blades can flatten by about 50%. I did have it on the car for many miles and it certainly didn't cause any problems but there again I don't know how effective it was or how many degrees the blades actually flattened by. Perhaps I will give it another try".

It is in the 1973 Derrington's catalog. I will leave you to read the spec and claims. For ones who are not familiar this company was very well regarded and were the people who sold the original alloy cross flow head for MGAs". -- Paul