The Seal Major - David Braid

At the launch of the Seal engine in 1947 Westbury noted that "It is my intention to produce designs for engines of both 15cc and 30cc, and equipped with either side or overhead valves". In 1950, with input from Westbury, the Seal Major was designed and released by David Braid.

This engine has proven to be equally as popular as the Seal. The essential differences for the Major are based solely in its capacity. Bore x stroke = Ø7/8" x 13/16" giving 32cc or With this simple change however, every single casting becomes larger than the Seal. Larger diameter pistons and liners dictate a longer, wider block, head and sump. Additional length in these components dictates a longer manifold…and so on.

Underneath it all however, this is the same elegant 4-cylinder side-valve engine as the Seal. So, why would you choose the Seal Major? A couple of reasons:

  • As the American's say "nothing beats cubes" and the Major has more umph. It performs well in 6ft launches and will even power a 5 inch gauge locomotive.
  • For the constructor, the extra size of the components (generally 30 - 40% larger) is often welcome.

In August 1959, British author and aeronautical engineer Nevil Shute wrote to a close friend:

"At the moment, however, the Seal Major engine is engaging my attention, and that will keep me busy for a quite a time although now that the book is finished I shall be taking a month or two of holiday and shall get on with it a bit quicker. So far, cylinder liners, pistons and gudgeon pins, and valve guides are finished, together with the timing spur wheels, and I am now starting work upon the crankshaft to be followed by the camshaft. I think the best plan on a job like this is to get all the bits and pieces made and then to tackle the final erection in one go when everything is to hand; otherwise one might tend to get in a bit of a muddle and one might find that parts already faced up and assembled might require some small alteration."

The Seal Major in Action


Seal Major - Material Kit

Seal Major - Material KitFrom:  £192.65

Seal Major - Drawings & Notes

Seal Major - Drawings & Notes£32.20