This is a fully working model of a 4 cylinder Holt 75 petrol engine. These were used around 1915, mainly in the USA, to power tracked military and earth moving vehicles. The original had a capacity of 22.9 litres and produced 75 horsepower at 550 rpm.
The model has a 1” bore x 1 ¼” stroke to give a capacity of 64cc. It will idle about 700rpm and go up to 4000rpm, but being a fairly long stroke it better suited to lower speeds.
It was built to a design by George Britnell and was constructed entirely from stock materials using manually controlled machines over a 9 month period.
It runs on petrol and has a distributor for spark ignition. Lubrication is by splash and it is cooled using a pump and a computer radiator.
