Head-Mechanics

Valve lapping is basically a way to seat the valve in its valve seat. This may need to be done if the valve has lost its sealing ability or if you put new valves in. The valves need to be matched to the valve seat.

First things first. you need to remove the valve from the cylinder head. This includes the springs. spring seats and collets.

This will need to be done with a valve spring compressor

here you can see the valve spring compressor and the groves for the collects which have been removed.

here you can see the valves and the valve seat

Here you can see the valve with the valve spring/s collets and retainers.

Now that you have the valve free of the cylinder head. we can begin to Lapp the valves. However I must say that some professionals disagree with valve lapping. If the valve and seat have been cut then valve lapping will only reduce the life of the valve. The cutting compound embeds itself in the valve and seat and with the heat and constant pounding it can bring on premature erosion and burnt valves. However these engines are not performance engines and the cost of a 2/3 angle valve job is not acceptable. For this type of engine as long as the valve and seat are thoroughly cleaned all should be ok.

First thing to do is inspect the valve for wear and erosion. In the picture you can see the erosion and pitting this is signs of a burnt valve and will need grinding

This valve only required light grinding to remove the marks and the valve can be seen below

after the valve has been ground the valve needs grinding into to valve so as the valve and seat are matched for an air tight seal. take the and place a little cutting compund around the cut surface/face. In this case we can use just fine compound in other cases start with coarse and and work down to fine. place the valve in the cylinder head and using a valve lapper rotate the valve clockwise and anticlockwise do this for a few minutes or untill the cutting noise dissapears.

when the valve is done place some blue die on the valce face and repeat the lapping process but without any compound. the die will dissapear were the valve contacts the seat allowing a visible area of seating. as below

blue is were the seat doesn't contact the seat and grey is the seating area

Repeat the process for the other valves.

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