Vauxhall 2.0L 16v Oil feed restrictor
Oil feed restrictor for the Vauxhall 2.0L 16v.
The oil feed restrictor that goes in place of the original non-return valve fitting in to the top of the block. The oil feed restrictor was originally designed for the GM works rally and race cars. It controls the oil feed to give the correct amount of flow to the cylinder head.
It replaces the original non-return valve design, which is not suitable for motorsport for the following reasons:
1. The delivery of oil to the cylinder head is too great and an excess quantity of oil will end up in the cylinder head. This means that in a dry sump system, there would be a need for an increased capacity of the dry sump tank and in a wet sump system, there would be less oil available in the sump. This will also increase drag of components, not only within the cylinder head, but the extra oil returning from the cylinder head past any moving components it meets.
2. The standard non-return valve can occasionally become jammed and no oil reaches the cylinder head at all causing failure.
3. The original non-return valve was designed to help keep oil pressure in the cylinder head when the engine was switched off, in reality we have never seen this function correctly.
The original non-return valve is either a one or two piece item depending on age and design. It needs to be extracted, normally using a slide hammer. If it is the two-piece item, the centre will normally come out and you will need to then tap into the remaining part with a tap of a suitable size, so you can then screw a bolt into each, then using some large washers tighten the bolt until the remaining part is extracted.
Please ensure that you have removed all the other oil gallery bungs from the block and the block itself is completely stripped and clean all the galleries before re-assembly. The new oil feed restrictor will then need to be tapped gently into the top of the block until flush ensuring the smallest hole is upwards.