One of the things that’s almost a "done thing" when reconditioning, refurbing or even just when the head is off of an engine is to lap the valves in. Valve lapping is the process of making sure that all of the valves match to their corresponding ports on the head so that there is no gaps at all when the valves are shut.

I haven’t ever done valve lapping before, so to begin I’ll run through the entire process. First of all, the valves and springs must be removed. It is imperative that the valves are marked to their corresponding ports and none of the parts are mixed up.

You must use a valve spring remover tool to remove the springs, so first things first, put one end of the tool on the bottom of the valve and put the other on the spring retaining cap and begin to squeeze. Bear in mind the amount of power these little springs have, so make double sure that the remover is fixed in the correct position.

After the spring has been compressed enough, the valve collet’s will be viable and you will be able to remove them. A small screwdriver may be needed to do this. Seriously watch out for your hands!…

Now very carefully unscrew and remove the remover tool. Of course, the spring will be trying its hardest to pop off and kill anything which lies in its path, so it must be done really carefully. Once free, the spring will drop off along with its cap, and then you can remove the valve. Carefully then remove the valve guide oil seal and throw it away. Put the collet, valve, spring and spring cap in a seal-able bag and label it with the correct port number.

And then continue to the next, following the same procedures. Once all valves have been removed and are all in separate bags marked with the port numbers you can begin lapping.

You’ll need some valve lapping paste, preferably two different grades: Fine and Course. Take a look at the valve seat and the valve itself closely and see how badly, or not, the surfaces are pitted. If its quite bad, then use the course paste, or if you think it doesn’t look too bad, use fine. Carefully smear the paste around the edge of the valve seat on the valve itself and put the valve into its valve guide. Clean, and then clean some more, the valve stem making sure there is no grit or dirt on the stem itself since this can damage the valve stem and valve guide very quickly!

Now, there are many ways of lapping valves from this point on. Most people use and trust on the sucker and hand method (which you’ll need to buy from an auto factors). However, after talking to a good friend who has had a lot of experience in this field, he uses a simple drill. Yes, cringe if you will, but it works - apparently. So, put the valve through its valve guide and attach the drill firmly to the collet markings on the end of the valve. Slowly spin up the drill and pull back onto the valve, so the valve seat rubs onto the face of the head, making sure the drill doesn’t go too fast. And that’s basically it - do this for 30 seconds to a minute.

Once happy, disconnect the drill from the valve and carefully remove the valve and clean both the valve and the head, again making very sure that no dirt or grit goes into the valve guide. If both face’s look good, then you can reassemble everything back together again.

Firstly, put the valve in its place, and put a NEW valve guide oil seal over the valve guide. For the price of oil seals, its worth putting one over all valves. Then, assemble the correct spring and spring cap and place over the top of the valve, and then attach the valve spring compressor over the top and begin turning. Keep an eye on everything, but in particular where the compressor is positioned on the valve face and where about the valve cap is positioned over the valve stem.

Keep turning until the valve collet groves can be seen, then very carefully put the collet’s onto the end of the valve. A very tiny amount of grease may be needed to keep the collect’s in their place before removing the spring again. If you didn’t notice when removing the collect’s which way around they go, the narrow end points toward the end. This is important since both the collet’s and valve cap is tapered to fit each other. Finally, carefully unscrew the compressor making sure the collect’s don’t ping off and the cap goes smoothly into the valve stem.

And you’re done! The valve lapping technique itself is probably not the best ever, but its worked for a friend of mine for the past 10 years or so, and it seemed to work quite well on my head (although I’ve yet to start it!!)