Mamod stationary engines were always, and still are, designed to be compatible with Meccano parts. From the start, the base plates had a row of holes around the edge with the standard Meccano size and spacing. The later models have changed the idea slightly by having only one hole in each corner but with a rectangular group of holes near the flywheel. However, the engine described here was the first to be designed specifically for use with Meccano and sold under the Meccano brand name. It has a large number of Meccano standard holes in the base and on two sides and is designed to be incorporated into Meccano models, not just attached to them.
The base of this engine was, I believe, designed by Meccano and was based on that of an earlier vertical engine also sold under the Meccano brand but (I believe) made in Germany, not by Mamod. The base on this example was supplied painted in Meccano yellow. (When it ceased to be sold as Meccano, it was brought into the Mamod range as SP3 but with a silver coloured base.)
The boiler is a fairly standard Mamod one with a vapourising meths burner. It has a chrome plated cover extending right over the top of the boiler, possibly at Meccano's insistence for safety reasons. The boiler is 1 3/4" dia x 4 1/2" long. It has a standard Mamod 1/4" safety valve, a water level plug and a dome.
The engine is a single cylinder, single acting oscillating cylinder type with a reversing lever which operates by shifting the trunnion. The bore is 5/16" and stroke 3/4". The crank shaft and flywheel are almost standard Mamod except that the shaft diameter is Meccano standard 5/32". The crankshaft is fitted with a Meccano standard gear wheel and chain sprocket. There is a pulley turned into the boss of the flywheel.
The whole thing is riveted together, which would make restoration a bind. Fortunately, it is in reasonably good condition so I've left it as is. However, a minor repair necessitated unriveting the cylinder mounting block from the base. I reattached it using nuts and bolts rather than rivets.