Thursday Trivia

Thirsday Trivia Welcome to Thursday Trivia where we offer up a historical automotive trivia question and you try and solve it before seeing the answer after the jump. It’s like a history test, with cars! This Week’s Question: How many camshafts did the Lotus-Ford Twin-Cam have? If you think you know the answer, make the jump and see if you are correct. 10-1-Twincam-Engine-Cutaway-Autocar-62The camshaft takes its name from its primary purpose which is most to carry a series of eccentric discs that serve to transfer rotating motion into linear motion. In an internal combustion engine, that’s typically used to effect valve operation.  While today most engines feature the camshafts mounted in the heads, proximal to the valves they operate, earlier designs maintained the cam in the block, employing a series of rods and levers to transmit movement to the valves. One of those earlier engines was Ford’s long-serving series of small fours known as the Kent motor. The Kent was introduced in the 1959 Anglia in 997-cc displacement and producing 39-horsepower. Over the course of the next decade it would see multiple increases in size, and a shift from a back-flow head to a cross-flow. Despite that change, which improved breathing immensely, the British Ford mill remained resolutely cam-in-block. That is, until Lotus got ahold of it. Lotus had been using the SOHC Coventry Climax FWE engine in their Elite, but that was considered too costly for its successor the Elan. Instead, Colin Chapman turned to Ford as they had a ready supply of small, efficient, and sturdy fours that the company was more than willing to sell. Chapman hired former BRM engineer Harry Mundy to design a DOHC head for Ford’s Kent motor. This was no mean feat considering the Kent wasn’t an OHC design, and resulted in a number of interesting design decisions, one of which was the use of the new timing chain case, which fronted the engine, as the housing for the water pump. Having had to change the water pump on one of these engines I can attest to what a pain in the neck that design is. One of the other design decisions was to retain the original camshaft in the block, despite the addition of two more in the new head. From Wikipedia:

Also notable is that the original camshaft was retained as an intermediate shaft driving the DOHC cam sprockets via a front-mounted, single – long – timing chain, having the side-mounted distributor and nearby external oil pump/filter assembly in original locations, requiring few modifications to the mass-produced iron block.

That of course gave the Lotus-Ford three camshafts as a means of cost savings. Sure, one of the cams served only to spin the distributor and oil pump, but owners could still brag about having a three-cam engine.

Image: LotusCortinaInfo

Leave a Reply

Your email address will not be published.

The maximum upload file size: 64 MB. You can upload: image, audio, video. Links to YouTube, Facebook, Twitter and other services inserted in the comment text will be automatically embedded. Drop files here