Why Are Valve Guides Important?

The valve guide is the boundary layer point between the head and valve. Proper valve guide material and design will affect many aspects of the engines operation. Firstly, if the valve is loose within the guide, this will affect the valve and seats ability to seal the expanding gasses. Secondly, material choice is very important, most if not all guides fitted to engines from Rover to Ferrari have cast guides. These guides do a good job at .

The problem is that these guides when cast have tiny gas bubbles in them called porosities. Each guide can react differently under varying degrees of heat exposure experienced under engine operation. In one guide for instance, this could cause the guide to become slightly slack in the cylinder head. Within another guide, the valve could be a little loose. Although these may not be felt in engine operation or they may. But these are the very variables we must avoid in the search for performance increases and more importantly, performance consistency and reliability. This is why specialist alloys that have far more consistent material density and thermal reaction, such as COLSIBRO, are implemented in the construction of these guides.