What causes snapped tappet screws and...

[bigbulli]

What causes snapped tappet screws and what subsequent damage can be caused because of this?
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1954 Barndoor
1955 Oval

[old DKP driver]

Poor QUALITY unhardened valve adjusting screws are probably number one.

Here in the U.S. this problem goes way back to the 1980's with inferior
screws where the ends were not hardened. and usually easy to spot with
the naked eye. since the screws are very dark in color about 1/3 of the length of the adjuster.

2nd. Would be because of weak valve springs or incorrect springs.
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V.W.owner since 1967

[bigbulli]

Many thanks for the reply, would it cause any other damage?
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1954 Barndoor
1955 Oval

[raygreenwood]

There were also a huge amount of 8mm screws in the 90s that were waaaay too hard. They dont wear at all, are hard on valve tips and have a tendency to snap just the ends of that contact the valve just below the threads.

I bought a set in the mid 90s that one by one over a period of two months, snapped off all but two tips. I one by one replaced them with OEM screws that had been polished.

After that I went to a set of 911 adjusters and have never looked back and find they are superior anyway. Ray