As a 911 owner now for the past 5 years, I must say that I enjoy working on this air-cooled masterpiece almost as much as driving it. However I quickly learned there were a few jobs that just aren’t fun; one of these being valve lash adjustments with the engine installed in the car. The combination of tight access to the valve/rocker arm area, the use of thin “tin foil” feeler gauges that are easily destroyed, and generally cramped quarters in the engine bay, lead to a frustrating and time-consuming experience. After my second lash clearance adjustment, I knew there must be a better way of doing this job.
After some thought, I arrived at what seemed to be a logical alternative. Knowing the rocker arm lash adjuster screw pitch (1.0 mm/rev) and the desired clearance (.1 mm), it’s straightforward to calculate the amount of turn required to attain the .1 mm clearance from a zero lash baseline. This is the principle upon which this valve lash adjuster tool works, i.e., just like a micrometer. With adjuster screw lock nut loosened, the tool is placed on the rocker arm with driver bit engaging the lash adjuster screw. The knob is rotated clockwise to get a metal-to-metal, zero clearance baseline. At this point, the moveable pointer is then rotated to align with the baseline mark reference. The knob is then rotated counterclockwise to the .1 mm reference line and proper clearance is established. Tighten the lock nut, and clearance is dead-on the money. And should tightening the lock nut cause the adjuster to rotate (as it sometimes does), it is easily seen on the adjuster knob and can be compensated for.
After constructing a prototype, I first tried it on my own ’88 911, then on two other friends 911’s with excellent results. It really cuts down on the time (and more so the frustration) in doing a lash adjustment. I can’t claim that the job has now become “fun”, but it certainly less of a pain when compared to the classical method. A few 911 owners have seen this tool and have encouraged me to go into production with it, and that’s what I’m planning to do. I’m proud to say that this tool is being offered exclusively on our host’s website and here is the link:
Porsche 911 & Carrera Cam Towers & Timing Chains - Page 3
A few pictures of the tool follow:
I’ve strived to make this a functional, quality tool for a good value and something that would be complimentary to the mechanical beauty of the Porsche 911 engine.