Z1OwnersClub GB

Hey, when are the shim buckets worn out? Do they wear out? Have some discolouration and slight scoring on the sides, imagine that’s normal wear and tear?

I had some that had gone blue and where tight in a old motor I bought in bits, I presume they had been ran hot/no oil, but they where tight in the hole a second hand set cured this.

Agree, I've had to swap buckets around before now to ensure no tight spots. Difficult to measure but 1 thou' is more than enough.

I've seen blueing on buckets where someone has increased the exhaust stud diameter and depth before! Going to far in can distort the material close by in that area.

Too loose and they rattle like feck!

Here's a typical set of manky buckets found on ebay.
Apart from the burnt on oil stain, the important thing, in my opinion, is the polished areas at the top and bottom of the skirt. This indicates the amount of rock that takes place as the cam applies sideways pressure. The top row 3rd and bottom row 4th are starting to show excessive ware, where the unpolished centre band is about half the length of the skirt.

With the camshaft out you should be able to see the amount of wear by pressing down the front edge then the back edge of the bucket.
By pressing down on the shim and wobbling the bucket back and forth you will hear the sound it makes when the engine is running.

King of Kings wrote:Hey, when are the shim buckets worn out? Do they wear out? Have some discolouration and slight scoring on the sides, imagine that’s normal wear and tear?

I've never seen any spec related data on bucket & bore i/d & o/d tolerances . I personally would not expect to see any either, as the contact patch on both areas ( bore & bucket ) is spread & covers a very large & quite evenly distributed area. I like others have seen them Blued but I have always just put that down to referred heat distribution from the guides in conjunction with the thin side walls of the buckets & all that perhaps happening on a Hot summers day whilst caught in stationary traffic with the oil then bubbling at 105 C+ ??? Like others upon stripping a head have also found in some engines that some were coated in cooked on oil and a little tight ...but when both bucket wall & bore faces where then cleaned with an old 3 part worn Scotch Brite cloth ...they wire fine & revolved freely with maybe a couple of thou clearance.
In relation to wear ! the only way I guess that can occur ...is through flogged out valve guides .......causing the bucket to then rock on the valve stem ends but to be honest ...again that large contact patch of the bucket wall faces would negate & disperse a lot of that oscillation affect ...... this just my option & I'm sure others will have theirs too. Cheers bud.

King of Kings wrote:Hey, when are the shim buckets worn out? Do they wear out? Have some discolouration and slight scoring on the sides, imagine that’s normal wear and tear?

They are all like that and it's normal discolouration from hot oil and heat cycling.
Rare to see a set of knackered buckets unless they are badly scored from an under lubed cooked motor, seen extensive race use or have been sat in damp conditions and rusty
Simple check is to run a mic over them to check for barrelling which is rare and otherwise they last virtually forever under normal condition.
Usual cause of loose buckets is wear in the actual head and this can be resolved by machining out the bores half a mill to 29.5mm and fitting GS1000 buckets .