Valve Adjustment Screws: The GoWesty Way

There is a small, threaded part in the valve train of a waterboxer engine called a valve adjustment screw. The valve adjustment screw is installed in the rocker arm, one per valve, a total of eight per engine. The only part of the screw that wears out is the tip that comes into contact with the valve stem tip.

By the looks of it, this part might seem to be rather benign, inexpensive, and inconsequential. You might also think that only the cheapest of engine over-haulers would reuse this part. Nothing could be further from the truth. At GoWesty, we reuse this part anytime we can, but only if the tip is okay. A bit worn is acceptable, but pitted or badly worn is no good.

We have very good reason to reuse the good screws. We build more waterboxer engines than all rebuilders on the planet, and we've had more of these things apart than anyone—and we have very good reason to reuse the good screws. We have found from experience that a good used, original VW screw is simply more likely to be reliable than any new ones we have been able to find, anywhere. We are NOT doing it simply to save money.

The only screws we have seen completely fail and fall apart in short order are NEW ones. Unfortunately, it is not just a matter of getting them from the "right" supplier. There are batches that work perfectly, and then the next batch half of the screws go belly up almost immediately. An original screw (with slight wear) removed from an engine is tried and true. If it has not failed after 100k miles, it isn’t going to fail! We realized the way to get the best consistency and reliability was to reuse as many good used screws as possible.

But the real problem is with the basic design. It was a really cheap solution VW came up with to transfer the angular motion of the rocker arm to the linear motion of each valve. What is really lacking is an intermediate piece between the tip of the adjustment screw and the tip of the valve. And that is precisely what all GoWesty engines get.

Every valve stem tip on every GoWesty engine is protected by a proprietary valve stem lash cap. This part adds an extra, hardened, rotating barrier between the tip of the screw and tip of the valve stem. So, even if a slightly worn valve adjustment screw is reused, this intermediate part allows for smooth operation and practically infinite life of the screw and valve stem tips.

Problem solved... on to the next one!