Although the bus was running very well at the beginning of spring I felt it had lost some of it’s get up and go by late summer after a number of reasonably long road trips. Certainly I had tuned it to perfection, but I had left out one thing, the valve adjustment. (note: later air-cooled engines featured self adjusting hydraulic valves, my ’74 has the manually adjustable type)
Driving the ‘74 Westfalia seasonally I probably put on about 3,000 miles in the past 3 summers, perhaps a bit more. Three thousand miles is the recommended interval for valve adjustment. To my surprise the valves were quite tight, .004 inch or less when I ran the feeler gauge through the tappets. As usual number 3 exhaust was the tightest as its cooling is impeded by the nearby oil cooler. The stock gap for intake valves on a 1974 Type 4 bus engine is .006 inch. The exhaust setting is a bit more confusing, if the motor still has the special sodium filled exhaust valves the gap should be .008 inch. However, I see debate on the Samba with some people setting them to .006 inch with good results. My personal experimentation found .008 to be a bit noisy and I settled for something closer to .006 or just closer to .007 for the exhaust. The fact is I don’t think I have sodium filled valves as a previous owner gave the engine a top end rebuild about fifteen thousand miles ago.
Then the great joy of sealing up the valve covers, finding they don’t leak, and putting the gas pedal down to find the bus has new found easy glide power. Like an almost new engine the bus is once again making as much as it can out of its potential 70 horse power. There is no need to jack up the car for this procedure. Happy motoring, and don’t be afraid to set your valves yourself.
The videos are from Chris Vallone at Classic VW Bugs dot com though the same principles apply to buses both upright and Type 4 engines.