ET Westbury Seal engine drawing error?

[Willem KotzeParticipant @willemkotze19252]

I have taken on the building of a SEAL engine from castings procured some 50 years ago by a late friend. His son would like to have the engine to be completed in memory of his father. I have the old Model Engineer copy and could not understand the offset cylinder centreline to the crankshaft centreline. I have now received a new set of drawings still showing this offset of 1/8".

On checking the casting it would appear as if there is sufficient material available for the skimming of the manifold port side to get the cylinders on the crankshaft centreline. The cam-, idler- and crankshaft gear centres would have to be verified.

Comments on the above and overall build of the SEAL will be appreciated.

[Willem KotzeParticipant @willemkotze19252]

Cylinder and crank centreline not aligned

[Neil AParticipant @neila]

Offsetting the cylinder centreline to the crankshaft was a design feature of older engines, it was used to reduce the side thrust on the piston on the firing stroke. I think it was offset in the direction of rotation, but I would have to check. Someone will probably remember which side it is. You rarely see it done on modern designs.

Neil

[Clive HartlandParticipant @clivehartland94829]

It is called, 'Desaxe' French I believe from older times. Neil describes the function correctly.

[Neil AParticipant @neila]

Thanks Clive, I could not remember what it was called.

Also I stand corrected on my statement about modern designs, from the internet, I find that it is in common use for automotive and smaller engines. I just had not seen it on newer large Diesel engines, I'll probably be corrected on that as well!

Neil

[Willem KotzeParticipant @willemkotze19252]

Thanks gentlemen for the responses. I have seen the references to the offset on steam engines for easier starting, but never expected it on the IC engines.

If this is indeed a design feature I will stick to it.

[JasonBModerator @jasonb]

Willem, you may want to take a look at this thread where a couple of other issues are raised such as the pistons poking above the cylinder head.

One of the hit and miss engines that I made also had the offset crankshaft to cylinder which was a feature of the full size version.

[Willem KotzeParticipant @willemkotze19252]

Jason, thanks for the link. Much appreciated.

Willie

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