Restoring a 1-3/4 HP Monarch - Part 1

Reclaiming its crown

| April/May 2010

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    The 1-3/4 HP Monarch antique engine being restored by Peter Rooke.
    Photo by Peter Rooke
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    Photo by Peter Rooke
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    Using a gib key chisel and clamp to remove the gib key.
    Photo by Peter Rooke
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    Using the puller on the crankshaft. Note the claws are around the hub, not the spokes.
    Photo by Peter Rooke
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    The starting handle. The top of the pin to hold it in place is visible.
    Photo by Peter Rooke
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    Straightening the crankshaft from the point of flywheel outward, using V-blocks, clamps and threaded rod to support it.
    Photo by Peter Rooke
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    Using a hacksaw blade to cut out the pin that holds the starting handle in place.
    Photo by Peter Rooke
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    The bend in the crankshaft from the point of the flywheel hub outward.
    Photo by Peter Rooke
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    The engine casting.
    Photo by Peter Rooke
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    Using the rotary file to remove the “rubbery” paint.
    Photo by Peter Rooke
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    The cleaned main casting.
    Photo by Peter Rooke
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    The area under the engine tag. The traces of original paint were indistinguishable from the patches of rust.
    Photo by Peter Rooke
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    Shims fitted to connecting rod before final profiling with a file.
    Photo by Peter Rooke
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    Tightening a stud using two locked nuts.
    Photo by Peter Rooke
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    Fitting shims to crankshaft, one side being rough shaped.
    Photo by Peter Rooke

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According to the tag, this engine, serial number 16690,  was manufactured by the Royal Engine Co. and given the name of Monarch. It should produce 1-3/4 HP at 500 RPM.

This is a “badged” Nelson Bros. engine, a company that is more widely known for its Jumbo line of gasoline/kerosene engines. Little is known about the Nelson Bros. Co., which was established in the early 1900s and went bankrupt in 1940 when all the company assets were sold. It later transpired that all the company records, blueprints, etc., were destroyed by the purchaser of the business in the late 1940s.

There is no register of engine dates for Nelson engines. This one is of later manufacture, identified not just from the serial number, or the fact grease cups were fitted rather than troughs for oil, but also that it was up-rated from 1-1/2 to 1-3/4 HP, which is believed to have started in 1916.

Nelson Bros. background
The Nelson Bros. Co. was based in Saginaw, Mich., and made identical lines of engines, many being sold through its marketing arm – the Royal Engine Co. In all, Nelson Bros. is believed to have sold some 400,000 engines, having, according to the company, reached the figure of 115,000 in 1921.



Engines were sold under a number of trade names, 50 or more, including Bohan, Maynard, Gray, Krackerjack, Macleod and Sattley. For more details and a comprehensive list of trade names, Mark Baier’s article “Nelson Brothers Company History” in the January 1993 issue of Gas Engine Magazine is most informative.

Marks on the Monarch
One can only guess at the date of this engine but it would be before 1923 as after this date they were sold with WICO high-tension ignition. I would estimate 1916 to 1920.