Whitworth history lesson...

...interesting tid bits via sohc.net and HondanutRider

An interesting trivia about Whitworth threads is that their pitch is Metric. While the profiles of the thread might be slightly different on standard Metric thread, they should match up and work if the same pitch is used. Whitworth nuts and bolts used unique head sizes that are different from either standard SAE of Metric sizes, and using a socket or wrench from these series will usually result in a "rounded" head.

Historically, Whitworth originated during/after WWI when the British brought some of the latest modern (at the time) thread cutting machines out of France for safe keeping during the war. These machines were capable of mass producing very accurate threads, but Metric of course, and the British war effort needed parts for the mechanized warfare that was evolving. After the war, they kept the machines and started producing their own "nuts and bolts" standardizing on the unique bolt heads. Because the original machines produced Metric threads, that's what Whitworth remained.

So, if a Whitworth bolt or nut gets "buggered" in removal. you likely can substitute a corresponding Metric-threaded one. However, it then won't be authentic and the "purist" concourse evaluator will mark you down.

...reprinted from sohc.net

Intro

I've been doing custom motorcycle work for about six years, and wanted to do something different. Different you want? Different you get. This is a 195x Triumph TRW500 engine. Its a pretty interesting little mill. It is a twin (its a Triumph, could it be anything else), but what makes it more interesting is that its a side valve engine. Essentially, what this means is that rather than the valves being buried in the head (like most modern engines) the valves are in the the cylinders, beside the pistons, hence the moniker 'side valve', or 'flat head' (no valves in the head).

This motor was a war bike, and never sold on the civilian market. The side valve design has essentially been eliminated from modern automotive and motorcycle markets do do its lack of power. This motor puts out about 15 horse power. Contrast that to a modern 500cc motorcycle engine that would put out more than 50 hp.

I mentioned these were never sold on the civilian market, but they are all over the place. After the war years they were sold as surplus still in the crate. A few still exist today:

http://blog.hemmings.com/index.php/2011/08/29/union-jack-in-a-box/

My first task is to acquire tools for this beast. Pre-unit triumph nuts and bolts used the whitworth standard, which is somewhere between standard and metric. Additionally there are a number of extractor tools I will need to get the thing a part. This should be fun, so stay tuned!!!