RAF 1A engine - Manufacture

The engine block, sump, front cover and flywheel cover were all cast in CC601ee
Aluminium Alloy and heat-treated to T6. The original parts were built up as necessary
and were used as patterns for the castings.

Because of this simple method of casting a lot of machining
was required both internally and externally.

Internally machining excess material to remove weight.

Externally machining details to the top of the block.

Once all this preparation work had been completed the finish machining could begin.

The block ready for line boring

Crankshaft
The original crankshaft was made of forged steel and was hollow with
plugs fitted to retain the oil. Its main bearings are roller and ball.

The crankshaft was made from 4340 billet. It was stress-relieved then nitrided to give
it a hard bearing surface. There was a drawing for the crankshaft which was from a
different model, the only difference being at the flywheel end. We used this drawing
along with the sample crankshaft to manufacture the new crankshaft.

Conrods
The original conrods were made from steel and machined to an H section.
They had a bush fitted at the small end and had caps fitted and white metal bearings
poured and then machined and hand scraped to individually fit each bearing journal.
The cap is held to the rod with BSF Studs and nuts.

The rods have been made from 4340 and machined
to a similar H section as per the original.

Bearings and Caps

The original caps were cast steel, the new ones were made from 1045 steel and
fitted as per the original with the required amount of crush on each bearing.

The bearings are all standard metric bearings and required a step to be
machined on the outer diameter of the bearing to suit the steel caps.

Cylinders

The inlet and exhaust valves have both benefited from the advances made in valve material.
The inlet valves are off-the-shelf and are made from stainless steel. They were trimmed to length
and have had a slot machined in them to retain the spring. The exhaust valve has been machined
from a truck exhaust valve.

Cam and output shaft
The Camshaft and output shaft were made from original parts. The camshaft is hollow
and is mounted onto the output shaft with splines and then tapered pinned in the exact
position. The output shaft has the main drive/timing gear fitted onto it.

Carburetor
The carburetor was made from a collection of parts. Although the castings were machined
by CAMS the majority of the work was taken on by retired machinist Dave Adams of Levin.

It is a testament to his skill and knowledge that he was able to
piece this together from what little parts he had.

The carburetor worked first time and only required a small adjustment on the main jets.

Engine complete ready for testing

Checking oil delivery system