This piece was christened BIG NED after the notorious bush-ranger NED KELLY, who famously took on the police force of colonial Victoria, Australia…. wearing home-made armour fashioned from pig-iron. The character of BIG NED was inspired by Marks visit to an art exhibition by Australian Artist Sidney Nolan featuring his portrayals of NED KELLY.
It started with a piece of 10″ round steel casing pipe that came into my journey, which the engine revolved around and I always had an interest in rotary valve cylinder heads. My previous work was always pocket valves. I decided to step out of the square and take the Rotary Valve quest, which many factories and private builders have done since 1919 and many have run successfully with some big issues and some small issues.
I have built 90 degree V Twins and I always was going to build a larger V Twin and so I decided to build a 3 lt based on Sidney Nolan’s NED KELLY, Square Heads and Square Cylinders.
In the 70’s while I was building my V Twin Drag Bike I was introduced to Rotary Valves. I had never looked or thought about one prior to that, I was to spend many years observing and assisting with machining and testing the XT500 Yamaha of Peter Gabalish, on his journey of Rotary Valves.
David Dunstan who is an Australian Pioneer from the 50’s and 60’s designed and made rotary valve heads on the grey Holden engine which was used successfully in speedway racing against Offenhausers – which was the motor at the time, also in hydroplane racing it was very successful at the time and he also made a complete kit to put on your road Holden and sold them, he was an unbelievable unrecognised Australian. He sold 32 heads that I know of.
In the early 90’s I was travelling back from a Canberra Drag race and pulled into Bundanoon, I met a bloke in the bar, and he asked me what I had in the trailer, I said “My drag bike, a home built 2lt V-Twin” and he was very interested in my work and he happened to mention he was into Hot Rods and he said he had an unusual head at home, he said it had a cylinder in it, rotating and no valves, and I nearly dropped my coffee on the floor because at the time, I was building my own wooden models to build my own rotary valves, so as you can imagine I was so keen to look at what this piece was, so I followed him back to this old falling down weather board cottage, the house was chock with car parts and all around the yard and he directed me down to this old shed and he got up on an oil drum and lifted down this head wrapped in a blanket and he unfolded the blanket. I wasn’t imagining much, but I went wobbly as it was a genuine Dunstan Rotary Valve, made in Melbourne by Dunstan himself, stamped no 29. This changed my whole concept of cylinder heads, it was a cast aluminium head, water-cooled with a beautifully cast iron rotor cylinder down through the centre of it with slots both sides for the ports and floating bronze seals.
Since that awakening I have learn’t alot about David Dunstan and his heads. The type of head I am using on Big Ned is a Roland Cross design valve, he started his work in the early 20’s in England.
2 Great Pioneers : Roland Cross and Aspen which you can research yourself.
I have spent my life working on, modifying and building Poppet Valve engines and then converted over to a new religion… “Rotary Valves”. When you realise the advantages of a Rotary Valve over a Poppet Valve are staggering…. They are an addiction.