Austin Healey 3000 Alloy Block Project
Casting Process
The two Halves of the mould, the blue blocks are filters
in the ingate system where the metal will be poured into the mould. These
filters help ensure that only clean metal enters the completed mould during
casting.
The core shown above provides the water jacket space around the cylinders. The core has been painted (darker colour) to seal in the gas generated within the core during the casting process. The gas escapes through the pink core prints ( locators) and out of the mould through the vents that can be seen at the left and right ends of the mould below. Aluminium reinforcing rods can also be seen in the core above between the cylinders. These rods strengthen the core and fuse into the casing during pouring.
The water jacket and cylinder cores are shown installed in the mould. The "D" shape ends on the cylinder cores are the locators where these cores lock into the crankcase cores. The small dark coloured core in the side of the centre crankcase core provides the oil gallery for the oil feed from the camshaft to the crankshaft.
Paull Wilson ( on left ) from Racer Pro fits one of the crank case cores, while Dave Woodhouse from DMD looks on. Racer Pro Build their own range of high performance Alloy Heads for Chevrolet engines and have been entrusted with the manufacture of the block castings.
The mould completed with all cores glued into position and ready for casting. The metal is poured into the mould through the smaller front centre hole and fills the mould from the bottom back up to the top through the risers, which are the 8 larger holes. As the casting cools the molten metal in the risers is drawn back down into to casting
The first alloy block casting is shown above. This casting is to be rough machined and sectioned as a means of determining that the pattern equipment is correct and that the casting has the correct wall thickness'. The aluminium alloy specification is -
Alloy AC601
7% Silicone
0.2% Iron
0.05% Copper
0.05% Manganese
0.4% Magnesium
0.05% Zinc
0.2% Titanium
Balance Aluminium
The completed casting is heat treated to T6.
Bare casting Weight is 38 KG (84 LBS) The original Iron Block is 82 KG (181 LBS) without bearing caps. It is expected that the completed alloy block with Durallium (extruded aluminium) bearing caps will be half the original iron block weight.
The block has been designed to produce a 3 litre and 3.8 litre engine. The 3.8 litre will incorporate offset conrods to match the bore spacing.
The block was cast Head face down, the slightly raised areas seen on the bottom face (below) are the remains of the casting risers, which are large blocks of metal cast with the block, their purpose being to feed metal back into the casting as it shrinks and cools. While the original works alloy block was ribbed internally like the standard block, the DMD block is beefed up and cast smooth.
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