Since 2003, all of Subaru's turbo-charged EJ engines have used valve buckets, or bucket shims to set valve lash. The bucket sits in the head and makes contact with the top of the valve, and it is this bucket that also makes contact with the camshaft.
In an effort to simplify the valvetrain, and reduce the number of moving pieces, Subaru created these bucket shims, of which there are about 90 different sizes to chose from. Each bucket in your engine is most likely a different size, so if you are disassembling your head or engine, you will want to pay close attention to each bucket, and make sure that you keep track of their location.
The Bucket pictured is part number 13228AB742, and the thickness of this bucket is 4.42mm. Each bucket has a different part number, but that part number does not usually have anything to do with the bucket's thickness. However, each bucket will be marked with 3 digit number inside, and that is it's thickness.
Because of their shape, they can be difficult to measure, so this can be a helpful piece of information to use if you are trying to adjust your valve lash.
As long as a bucket is not showing significant signs of wear, it is fairly common to re-use a bucket if it is the correct size that you need. But if there is any concern about wear or damage, the best practice is to use a new bucket.
If you are taking a measurement to determine the valve bucket you will need, you need to start with a bucket of a known thickness, install it over the valve, and then use a fealer gauge to measure the gap between the bucket and the cam. Once you know what the gap is, you can calculate the thickness of the bucket that you will need to have the correct clearance.
If you are working with an experienced machine shop to build your heads, there is one other option worth mentioning to set your valve lash. An experienced shop may offer a service called "valve tipping" where they remove some material from the top of the valve to get your valve clearance set, rather than replacing the buckets themselves. Since there are 16 buckets total, it can be somewhat costly if you have to replace them all, and this can be a less expensive option. And when done correctly, the end result should be the same.
But because material is being removed from the valves, it is possible that this can create a situation where if you go in to adjust the valve lash a second time, there isn't a bucket of the thickness that you need, since they are only made in a rather narrow range (4.38mm to 5.65mm). Usually only a shop that is experienced with Subaru head will offer this option, but if there is any doubt about the range that you will be left with, or the end result, it would be the best practice to just replace any necessary buckets.
- Jon Cooley
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