Factory specifications for this vehicle:

Deze Austin Healey is eigendom van een Italiaanse liefhebber en komt dankzij zijn bouwjaar (<1955) in aanmerking voor deelname aan de Mille Miglia. De auto is enkele jaren geleden perfect gerestaureerd en verkeert zowel optisch als technisch in zeer goede staat. De motor was eerder al gereviseerd, maar had inmiddels weer onderhoud nodig.

In 2024, the car participated in the Italian Mille Miglia, but unfortunately did not reach the finish line due to a broken crankshaft, which broke between the second and third cylinders. This is more common with this type of engine, which has a long stroke and is supported by only three main bearings in the block.

The engine was removed and dismantled for an initial inspection. At first glance, the damage appeared to be limited to the crankshaft, although the piston had made contact with the cylinder head due to the fracture. Fortunately, neither the piston nor the cylinder head appeared to be irreparably damaged.

After complete disassembly, all parts were cleaned and inspected. The engine block was carefully checked with a Magnaflux device to see if the cast iron had suffered any cracks due to the broken crankshaft.

All relevant dimensions of the engine block have been recorded to provide a solid basis for rebuilding. Once all dimensions are known, informed decisions can be made about necessary modifications and new components. If performance improvements are desired, it is crucial to know the exact specifications of the engine, such as cylinder capacity and compression ratio.

During this phase, the following damage points came to light:

1. The most obvious damage: the broken crankshaft. Inspection revealed that the main bearings and bearing housing in the block were damaged and needed to be machined. The axial bearings were severely worn.

2. The top surface of the engine block was not flat, and there were clear signs of leakage at the head gasket.

3. All cylinder bores were out of tolerance.

4. The cylinder head was not flat, and leakage was visible here as well.

5. Several valves were sitting too deep in their seats, which were severely worn.

6. Some valve stems were ground down at the top as a temporary solution for the damaged valve seats.

Based on these findings, we had to make a few choices regarding the overhaul approach, starting with the broken crankshaft:

1. New original cast iron crankshaft

2. Crankshaft from an Austin Taxi (diesel) engine

3. New steel crankshaft

The owner wanted to increase the reliability of the Healey. A new standard crankshaft was therefore not an option, because the risk of recurrence remained due to the material.

The Austin Taxi crankshaft seemed like a good alternative, but required modifications to the center bearing due to different dimensions, which would have affected the connecting rods. Due to time constraints and the fact that this type of crankshaft is made of similar material to the original, it was decided not to pursue this option.

Ultimately, option 3 was chosen: a new steel crankshaft from Denis Welch Motorsport (UK), specially developed for high-performance applications. This crankshaft is balanced and is combined with special connecting rods with floating piston pins. The matching bearings are also included.

To address the worn cylinder bores, the block was bored and honed. The new bore size is 88 mm. Pistons were ordered from Denis Welch Motorsport. The original pistons have a 21 cc crown. To increase the compression ratio from 7.5:1 to 9.0:1, the volume of the new piston crown was reduced to 14 cc.

Further upgrades to the engine:

1. Hi-beam style performance connecting rods installed
2. Equipped with exhaust valves that are 3 mm larger than the original (competition spec)
3. Steel head gasket mounted with high-strength studs and nuts
4. Lighter flywheel installed: 8 kg instead of original 21 kg
5. Special seal + housing behind the flywheel to prevent oil leakage
6. Additional oil return channel drilled into the rear bearing cap, as was also done by the factory on later models.

After rebuilding, the Austin was tested and tuned on our own test bench.

1. The first test, still with the original ignition distributor, yielded a result of 77 hp and 216 Nm.
2. To improve this, a programmable CSI-Pro ignition was installed, allowing the advance curve to be adjusted live on the test bench.
3. With this new ignition, the engine delivers 82.7 hp and 223.9 Nm, which is a very good result.

We thoroughly enjoyed working on this Healey. The engine has been properly serviced in all the key areas, resulting in a reliable setup.