Another mystery engine competition

A very Happy New Year to all

I came across this old pic in an online archive which got me curious. It didn't have a title. The chassis looks distinctly ABC 12hp /Sports.

But the flat twin engine looks very unusual, some kind of prototype with unique valvegear?

Very much an ABC chassis with its unusual cantilever suspension with gearbox set well back. No front brakes so early 1920s design.
I really can't work out how the valves are actuated as they appear to be at the side of the cylinder rather than on top when viewed with the cylinder vertical. The absence of a a pin for a conventional rocker and the substantial fixings for the "push rod" tube indicates a totally different arrangement.
Quite how the valve operated by such an arrangement fit into the combustion chamber is another mystery.

Here's my fivebob's worth, about the valve operation...
Those substantial 'pushrod tubes' contain, in fact, rotating shafts: each with a cam at its outboard end. Each cam works a valve, angled down in the direction of the (visible) sparking plug. There must be a pocket 'above' each piston, for the valve heads and 'plug points.
Where do I claim my winner's coconut?

Paul,

That was my initial though although it does make the combustion chamber a very odd shape but with a compression ration of around 5:1 that would not be a problem.
The main problem with that solution is working out how to rotate the shaft at the cam end. The camshaft is in the standard position and the tube connection appears to be in line with the camshaft so how does it impart rotation?

Roger

Hi Roger,
Let's start afresh.
What would normally be a camshaft, is in this case a camshaft driveshaft.
It does its driving via bevel gears to the inboard end of each camshaft-proper. (These gears could also perform a 1:2 reduction-stage). The hefty 'pushrod tube' surrounds at their inboard ends, carry the inboard camshaft-proper bearings, which resist radial and axial loads. There are similar bearings (except for radial-restraint only) at the camshaft outboard ends.
I liked your compression-ratio rations!

Paul,

I now realise that the engine is a totally different design to that of the standard 12hp and the take off tubes to the head are not in line with the camshaft. This means that the rotation on the rocker rod could be by means of a face cam. Dougal Marchant designed the face cam Chater Lea engine for 1924 that used a vertical bevel driven camshaft actuating rockers in the head.

It looks as though there is a Super Sports in the background so this would be a works special with knock off hubs and that would explain the radical valve gear design which would have been experimental.

I hope I've used up my ration of auto-corrections!

Regards,
Roger