Club 80-90 Forums

itchyfeet wrote:leave it a couple of hours and you will have compression I bet.
Tappets once preloaded need to be left to bleed down until the valve closes.

Mocki wrote:iirc haynes also tell you to set the rocker adjustment too many turns in.... double check!!

meggles wrote:

Mocki wrote:iirc haynes also tell you to set the rocker adjustment too many turns in.... double check!!

It states 2 turns in from initial contact.

Richard Atwell wrote:Bentley (both Bus and Vanagon versions) say the adjustment should be two clockwise turns after the valve adjusting screw makes contact with the valve stem but some folks think the adjustment should be 1/2 turn. If the lifter was dry and you were to preload the lifter 1/2 turn, that's about 0.015" (0.38mm) movement of the piston inside while 1-2 turns would be 0.030" - 0.060" (0.76mm - 1.52mm). I will explain how much to adjust the lifters later...

If you only adjust them by 0.5 turns the lifter won't compress enough and you'll upset the rocker geometry accelerating valve train wear. In practice what happens when you don't preload the lifter enough is it will take too much time to pressurize and you won't get enough valve lift. This will cause the engine to labor and sound noisy. The noise is often heard coming from the camshaft (center of the engine).

Two turns of the 10mm valve adjusting screw with 1mm threads will preload the lifter ~1.5mm (remember the 1:1.3 rocker ratio). This is about half the distance that the piston inside the lifter can travel. If you use too little preload you will stress the lock ring that holds the lifter together when the lifter socket maks contact with it. If you use too much preload, the plunger may bottom out at first, then as the lifter pumps up to compensate the valve may not close properly and compression, performance and valve life will suffer.

How about 1.5 turns instead of 2? In practice, this seems to be as acceptable as the factory recommendation and a feel good insurance against the ills that other people have experienced over the years following the factory recommendation. In my experience, 1.5 turns of adjustment after the engine has run for many miles remains around 1.5 turns. Sometimes the adjustment is 1/8 of a turn more or less but you will be in the ball park and the engine will continue to run properly thanks to the flexibility of the design. The fact that the setting can exceed the initial adjustment supports the idea that 1.5 turns is better than 2.0 turns.