Early photo of AC-6 engine

[Old Crock]

Here’s an early photograph of the AC Six engine. It’s from about 1920/1921 and is certainly the earliest photo of the AC 2-litre engine that I've seen (and may be the first?). I don’t think it’s ever been published but may be wrong(?) Likely taken at a show, as it appears to be a display chassis, and there’s a barrier in the background plus an AC 12/40.
   
   This is an interesting photo as it shows an early inlet manifold - one I've not seen on a car - which is more rounded than the mid-20’s production models (which had ‘squarer’ angles). Note also, the magneto ignition and the rounded rocker box; later were more flatter-topped.
   
   

[ACOCArch]

quote:Originally posted by Old Crock
   

   An interesting photo of the chain driven ohc engine.
   
   The earliest engines had a shaft driven ohc with a pulley on the rear of the camshaft to drive the dynamo. The engines came in two sizes, with 56mm or 65mm bore and 100mm stroke.
   
   The earliest engines also had six inlet ports, as opposed to siamesed ports. The three branches of the inlet manifold were correspondingly broader, with each branch having two separate tracts.
   
   The engine in the photo may therefore have a six-port head.
   
   Full details and photos were published in ACtion Archive dated December 2009

[Old Crock]

After a little more research it seems that AC did display the 6-cylinder engine at the Motor Show at Olympia in 1919 (its first viewing) then again in 1920 and 1921. There are stand-alone photos of the earliest engine, with the cam-driven dynamo pulley (e.g. in Jock Henderson's book), as referred to in the last posting, but the photo above shows the modified engine actually in a chassis. When Selwyn Edge tested the 6-cyl. prototype for 'The Auto Motor Journal' in 1919 photos of the car showed it to have single-pane screen, one door and what appears to be disc-covered wheels.
   
   The photo above may well be from the 1921 Olympia show when the 6-cyl was displayed as both quote 'bare chassis and a complete 2-seater' unquote and was now a 'production model', so I assume the first deliveries of 6-cylinder cars was in 1922. The earliest car surviving, even 30 years ago, was from 1923.