Seagull Engine Construction Diary

Making a 10cc twin 4-stroke to the E T Westbury design


Hemingway Kits

Perhaps better known for kits for making tooling, Hemingway Kits also provides kits for quite a number of IC engines designed by E T Westbury and others, and is introducing steam engines as well. I have found the proprietor, Kirk Burwell enthusiastic and pleasant to deal with.


I had a job tracking down a small bottle of Loctite 648 high temperature retainer, intended (but not tried yet) for the cylinder liners and valve guides. I eventually found 5ml bottles at Skydrive who delivered very promptly.

Lapping Compound

A lapping compound that breaks down, called Timesaver is available in two hardness grades and 4 grits from
G A Watt Engineering Supplies, 9 Doune Crescent, Bishopbriggs, Glasgow, G64 3JG - 0141 563 6520.
At the time of writing, a 1lb tin of compound is £36-90 plus carriage and VAT.

Put off by the price, I got some fine garnet lapping compound from Brownells. I have not used either yet, but I have used Brasso, and it seems pretty good.

Joint Sealant

The engine is built, as Westbury advises, without gaskets. A jointing compound is therefore required. Westbury suggests 'varnish' in several places, and I think I read 'copal varnish' somewhere, but can't find the reference. Traditionally formulated artists' varnishes don't seem to be readily available any more, and in any case there is probably something better that is designed for the job. When I first assembled the engine I used Hylomar but was later told by someone on a web forum that Wellseal was the stuff to use. I had not even heard of it, but bought some and was converted. It is a thin brown liquid made from a natural resin in a volatile carrier. I have not put links to these products as a search by name will easily find them.


The big-ends and centre bearing cap are fitted with high-tesile cap-head screws, done up tight. There are some 10-BA brass screws inside the timing cover. Everywhere else I have used home-made studs, with home-made washers and bought nuts. The 8-BA studs for the coolant flanges are stainless steel. The rest are mild steel. The manifold is fitted with 6-BA nuts with 7-BA hexagons, and 'small hexagon' nuts are also used on the flexible drive coupling.

Internet Groups and Mailing Lists

The best site I have found is Home Model Engine Machinist. It is a very active forum with lots of people posting descriptions and photos of their work, some of which is stunning, and answering questions with enthusiasm and (often) good advice.

There are a couple of now virtually defunct Yahoo groups: ET Westbury Engines and Strictly Miniature Internal Combustion Engines. People do still watch these groups, so a posting will be responded to. It's just that posting does not happen very often these days.

Email me (see below) with other links I should include.

Links to other Seagulls

Graham Meek built an air-cooled version with an electric fan, and wrote about it in Engineering in Miniature, October 2010 issue, also here. As well as some interesting ideas, there is some nice workmanship on this engine.

Ron Chernich (see below) acquired a part-built Seagull, with which the original builder had evidently run into problems. Ron never did anything much with it, but his wry notes highlight the need for great care with the head bolts and water passages.

There is some footage of a Seagull running at idle on YouTube.

Other web resources

The late Ron Chernich's long established monthly newsletter is a gold mine.

A most valuable little program is Duncan Munro's ML7 Gear Calculator which will produce a set of possible gear trains for any thread pitch. It will store any gears one may have beyond the standard set.


Westbury, Edgar T (1936, 1992), Model Petrol Engines, TEE Publishing, ISBN 0 905100 34 4.

Mason, L C (1976), Model Four Stroke Petrol Engines, Argus Books, ISBN 0 85242 431 0.

Stride, Malcolm (2007), Miniature Internal Combustion Engines, Crowood Press, ISBN 978 1 86126 921 8.

Law, Ivan (1998), Gears and Gear Cutting (Workshop Practice Series), Special Interest Model Books, ISBN 978-0852429112.


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