Classic Cob From the shed

A Water Cooled Triumph

Well known pre-unit Triumph guru, Paul Dempsey from Renmark, South Australia recently sent me photos of another special he has built. It is a 1949 T100 in a 1956 swinging arm frame fitted with a water-cooled cylinder head. He acquired this from a fellow in Adelaide who at one stage was in the RAAF and stationed in Sydney. Another service member had purchased this engine in Sydney about 1960 when it was fitted in a small racing hydroplane. When Paul told me about this it reminded me of an encounter I had around the early 1980s. I got to meet an elderly chap living at Forster named, from memory, Norm Cooper. He told me he had been a workshop foreman for many years at a motorcycle dealership in Wentworth Ave, Sydney which I seem to recall, but not certain, may have been A.P. North. He was friendly and very interesting to talk to. He insisted, rightly or wrongly, that the only balance factor to use in any engine was 50%. He would ask for a 20 cent coin and draw a series of circles on paper and then write in various balance factors and show which way the crankshaft would have a tendency to distort out of balance. There was no mention or consideration as to what frame the engine was to be fitted into. He balanced both of the engines used by the late Graeme Gates in his twin Norton, and as anyone who saw him ride knew that he revved the engine very hard. Cooper told me about a motorcycle engine he built where he machined the crankshaft from the axle of a railway carriage and the aluminium barrel from the centre portion of a variable pitch aircraft propeller. He used a 250 BMW head and fitted it into a prewar Triumph frame. However now getting back to Paul Dempsey acquisition, Cooper used twin pre-unit Triumph engines in a hydroplane that he raced on the Georges River, Sydney in the early 1950s. He burnt out several exhaust valves so he made a water jacket around the head which then solved the problem. I think he told me that he relied upon convection in some form to create a water flow. Paul has fitted a radiator mounted upwards of the head which would allow for the heated water to rise and the colder to sink downwards towards the head. I am unable to say if others undertook the same modification as Cooper but there is a possibility that this could be the same head that he used all those years ago. Just when you think that this machine might be unique, I made a phone call to another Triumph guru, Bryce Findlay and learned that he has a similar engine with a water jacket around the head on a 1951 650 Thunderbird. So perhaps after all it was a common modification back when improvisation was the order of the day.

Sweltering at Goulburn

The Goulburn Swap Meet held Sunday the 21st January saw 254 traders which was about the same number as last year. However the buyers were down to about the 1100 mark no doubt due to the very uncomfortable temperature which in the high 30s. There were some good buys around at competitive prices. The committee has identified several areas upon which they can make further improvements. Graham Sinclair had one of the Australian-produced RTV Vincent engines which he had sold prior to the swap. When started up on Saturday afternoon and Sunday morning it sure made a racket. For sale was a 1922 500 Invincible JAP believed to be one of only 4 or 5 assembled in Swanson St, Melbourne, and believed to be the only one still in existence. There was also a 1914 500cc Precision made in UK but assembled by A G Healing in Elizabeth St, Melbourne. Both of these machines are for sale and further details can be obtained by contacting Graeme Sinclair 0418 711 405. See you next issue, Pete You can get in touch with Pete at... cob.smith@bigpond.com or call (02) 6553 9442 after 7.00pm