It’s fascinating to see a small engine being assembled. Despite its size, it contains all the components of a full-size engine, but scaled down to fit on a desk. Let’s watch this 21cc inline-six engine come together and run.

This engine comes in a kit with everything needed for assembly. However, some fine-tuning is necessary for optimal performance. The assembly process follows the same steps as building a larger engine. First, the crankshaft is fitted into the block. Then, the pistons and connecting rods are installed. Since it is an overhead-valve design, the camshaft is inserted into the block.

The provided mechanical water pump doesn’t work effectively, so the builder replaces it with a separate electric one. Additionally, the supplied cylinder head gasket is not satisfactory, so the builder creates an aluminum one instead. There is also an issue with the distributor design, as the existing hall sensor cannot fit, requiring the use of a rotary tool to create space.

Similar to a full-size engine, the work doesn’t end once the engine is running. The initial tune results in a mixture that is too rich, and the ignition timing is off. After making some adjustments, the little engine sounds great. It revs quickly, and the laser tachometer demonstrates that it can even exceed 10,000 RPM.

There are still plans for further improvements. The builder intends to install a functional mechanical water pump and may also modify the exhaust and switch to a single-carburetor setup.

This builder is skilled at assembling and tuning these miniature engines. In fact, they have also built a tiny supercharged V8 and even constructed a three-speed manual transmission for a small four-cylinder engine.

The Howin L6-210 engine, which is inspired by Ford’s 300-cubic-inch inline-six, is available for $1,299.99. However, there is currently a $200 coupon being offered by the seller. The Ford 300-cubic-inch inline-six is well-known for its torque at low revs and was used in F-Series pickups from the 1965 model year until 1996.