Upgrading To Solid Rocker Shafts From Stock, OEM VW
The stock rocker shafts are great, no frills shafts that work great on a stock head. Once you add a set of high rev single springs or dual high performance springs on your heads, you begin to see their limitations in a hurry and problems start. The reason for this is because the higher than normal side loads placed on the retaining clips and warpy spacers from the increased spring pressures, causes these parts to break or come apart. When these parts break, the pieces have to go somewhere, right?? Chances are they will find their way down the push rod tubes and into the crank case. But that's only half the problem. Because of the engine's design, the #1 & #4 exhaust rockers tend to be the ones that break the spring clips and warpy spacers the most. This ends up causing the rocker to chew-up the top of the valve retainer while putting extreme side loads on the valve stems. This condition can rapidly cause the destruction of an otherwise good motor. The answer to this problem is simple; install solid rocker shafts.
NOTE: Solid rocker shafts are MANDATORY for ALL motors built with anything more than stock valve springs
A solid rocker shaft kit has no warpy spacers or retailing clips to break. Instead of warpy spacers and clips, they use a series of shims, a large center spacer and two end caps with bolts holding it all together.
Here is a comparison shot of a stock rocker assembly (top) and a rocker assembly with solid shafts (bottom).
Proper set-up is crucial for long engine valve life. I recommend doing this in a well lighted area PRIOR to bolting on the heads to the engine. It can be done after the heads are on with NO ill effects, but it's just WAY easier to do before assembly. You will need to assemble the rockers assemblies with a few random shims at first and seat it firmly onto the rocker studs. While doing the shimming process, I find it easier to just leave the lock washers off of the end caps for now so that I can put it all together with my fingers. You will end up taking it all apart several times during this process and being able to just use your fingers makes it go a lot faster. The goal in shimming is to get your valve adjuster to contact the valve stem just SLIGHTLY off center. This way, the valve will slightly turn in the guide each time the valve is depressed ensuring the valve and seat contact in a different location each time and wear evenly.
Here's an example of a rocker adjuster shimmed CORRECTLY. Note that the adjuster is just slightly off center. This is what you should be striving for when shimming.
Here is a couple photo with two adjusters that are set-up INCORRECTLY. Note that the left adjuster is half off the edge of the valve stem. This will quickly destroy the valve and possibly the whole motor of the stem were to break off. The rocker on the right is contacting the valve stem directly in the center
This is just a comparison shot of the swivel ball valve adjusters I used when I upgraded to heads with stainless steel valves. You MUST either upgrade to this type of adjuster OR use hardened lash caps to protect the soft SS valve stems from mushrooming from the constant pounding from the adjusters. I would recommend upgrading to this type of adjuster no matter what type of heads or rockers you currently run. They provide a more consistent gap and make valve adjustments MUCH easier. When you use this type of adjuster, you must use the supplied rocker shaft mount spacers since the ball-end of them protrude further than stock.
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Revised: August 29, 2003 .