The chassis of this engine started life as a bog-standard Mamod SA1 of late 1970s vintage. I purchased it as a box of bits. The previous owner had started repainting but hadn't got far. The boiler was "beyond economical repair", which is probably why it was put on Ebay. Rather than complete the restoration, I decided to convert it into a Stanley style charabanc, based on one I saw at GDSF.
I replaced the boiler with a vertical one, obtained from a Midwest Heritage launch engine kit. I fitted a butane burner under the boiler with the gas tank under the front seat. I fabricated a suitably shaped bonnet from a tin lid and aluminium sheet. The steering mechanism had to be completely redesigned to bypass the new boiler. This I did with a made up linkage and a pair of Meccano gears.
I replaced the second stage of the belt drive with a chain and pair of sprockets. I also modified the first stage to reduce speed. I extended the existing SA1 bodywork with aluminium sheet to accommodate four rows of seats. The new seats are made from balsa wood covered with vinyl. The front seat is removable to give access to the butane gas tank.
The boiler is fired by a butane gas burner with a ceramic element. The dimensions of the boiler are 2 1/4" dia x 2" high. It is fitted with a traditional sight glass and a Mamod safety valve. The single acting oscillating cylinder, fitted with a reversing lever, is the standard Mamod type from the SA1, 8mm bore x 20mm stroke.
The rear axle (strictly speaking only the near side wheel) is driven through a two stage reduction, with a belt first stage and chain second stage. The belt drive is made from components from the original SA1. The second stage is made from Meccano parts.
The overall dimensions of the whole vehicle are approx 500mm length, 52mm width x 205mm height.
Photos and a description of the conversion can be seen here
Here is a video of it running. (This video shows just how difficult it is to control both a camera and a vehicle at the same time!)