Viking 2,5cc

Name Viking Designer Tommerup Clausen
Bore ?mm Stroke ?mm
Type Compression Ignition Capacity 2,5cc
Production run 20,000 [1] Country of Origin Denmark
Photo by Bert Streigler, Per Byrgren Year of manufacture 1950-69



We don't know a lot about the history of this beautiful engine. The one pictured here is a pristine, NIB from Bert Striegler's collection. Even the box and papers (in Danish, naturally) are in perfect condition as seen here. The accompanying customs declaration gives the date shipped as 1960, so we can place manafacture as some time prior, but from the box condition, probably not a lot earlier.

The detail and workmanship appears first class: look at the how the fins flair into the inlet boss in this photograph. To do this requires they be cut with a slitting saw (or gang of them) while the crankcase is rotated around the bore axis between precise limits. The red fuel tank is also very eye-catching and the little locking thimble on top of the spraybar makes for an excellent air-proof joint—a feature found on high performance engines like Dooling, Super Tiger and older McCoys.

No, this is not an unusual design feature; the apparent obtuse angle between cylinder and crank bores is due to folds in the paper! More unusual features are the forward facing exhaust (a feature later used in high performance Russian team race diesels to place the hottest part in the most unobstructed air-flow) and the screw in plug in the top of the cylinder that retains the liner in the long bore. Notice also the pinned prop driver. This feature is pure Dyno 1, leading me to think that regardless of when this engine was made, the design dates way back.

These photos came from Per Byrgren and confirm the details of the sectioned factory drawing. We also see that the ecnter of the compression screw has been drilled out. The weight saving in doing this additional manufacturing step is nothing, however this little extra has been shown to significantly reduce the tendency of compression screws to unwind under vibration as it reduces the chance of point-contact between screw and contra-piston. We also see the rather thin crankweb that has been extensively cut away, balance not being all that important in slow turning old diesels, and the tall piston that was thought to be necessary to ensure good compression.


[1] See also:




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