A productive day on the rebuild yesterday, learnt a huge amount and got to have a good look around the inside of my engine.
I finally learnt where the valves live and what they look like (still not absolutely sure what they do but that isn’t my primary concern at the moment.)
Section 4: Removing the Valves from the Heads
Time Taken: 1 Hour
Tools Required: Valve Spring Compressor, Small screwdriver, hammer, socket, Larger Hands
As part of my educational day I learnt that the valves in a WBX engine look like a trumpet (or a hunting horn for the Upper Classes). They are a solid piece of metal and the base of the valves are the 4 circles you can see when you remove the heads.
As the above picture shows, there are 4 valves in each head and there are two different sizes. The smaller diameter ones are Exhaust valves, the larger are Inlet valves. They need to be removed from the head so that where the large, circular ‘trumpet’ of the valves contacts with the head can be cleaned - this is called ‘lapping the valves’ and appears to be one of those terms used to put the general public off attempting this sort of thing so that garages can charge loads.....
Lapping valves is basically using a grinding paste to smooth the contact surfaces between the valve and head to make an air and water tight seal - I will cover this in a separate section as today was all about removing the valves.
If you look at the head from the other side you see four large springs- these, unsurprisingly, are called Valve Springs
These grip the other end of the valve (the valve stem) and provide the tension to pull the valve tight against the head. The valve stems are held in place by a collet.....another one of those terms
From Wikipedia: A collet forms a collar around an object and exerts a strong clamping force on the object.
This is a collet from one of my valves - a two piece, tapered sleeve that sits around the valve stem and, when the spring is in place holds the valve tight.
To remove the valves you have to take the tension off the spring, pick out the two pieces of collet then you can expand the spring and there is no longer anything to grip the valve stem so the valve can slide out. To do this you need one of these
This is a Valve Spring Compressor - basically, a large clamp that allows you to crush the spring and remove the collet.
Now, the springs are really tough and couple that with the fact they work in quite a dirty and hot place, and have probably been there for many years, they aren’t the easiest things to compress. To give myself a chance (and to save the spring compressor......as it wasn’t mine) I hit them with a hammer..
Using a similar diameter socket I gave each spring a sharp tap just to help free them up. Then, grasping the Spring Compressor I got it into position on the first spring
Jaws on the perimeter of the spring cover (this can be adjusted on the tool I was using)
The flat piece dead centre on the valve ‘trumpet’.
It’s then simply a matter of pressing the handle, compressing the spring, the tool locks and holds its position while you remove the collet...........no it’s not, it’s really hard and it hurt my delicate hands. Honestly, I struggled as I have quite feminine hands and found it hard to exert the pressure required to compress the spring. I ended up have to use both hands and then had nothing free to remove the collet or the tool would spring unlocked etc etc.
I managed in the end......above, you can see the spring is compressed and you have access to the collet. I used a small screwdriver to separate the pieces and flick them away from the valve stem. They often appear to be stuck as there are traces of oil that causes suction against the stem so you end up chasing them round in endless circles with your screwdriver.
Sometimes, the tool is in the centre and will pull off to one side with the spring not compressed evenly on both sides. This sometimes means that one piece of the collet is trapped between spring and stem - you can try to rotate round the stem but if it’s stuck fast you have to reset the Compressor.
Collet out, tool removed. There is a disc that sits on top of the spring.....it probably has an official name, I don’t know what it is.
The next surprise is that there is actually two springs per valve - who knew?
Remove these pieces and you get a clear view of the end of the valve stem with the recesses that the collet sits into. If you give the valve stem a push this is what should happen on the other side of the head
Now, this bit is important I’ve been told - you need to keep all the pieces from each valve separate and label them accordingly. I stole of box of freezer bags from my kitchen for this very purpose.
Each cylinder will have an exhaust and an inlet valve as mentioned above and each one will be bagged separately- 8 freezer bags for both heads. Contents of each bag: 1 Valve, 2 Collet pieces, 2 springs, 1 Disc
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