I recently had the head in my 250SE rebuilt after it had cracked (thank god for aluminium ). Since the head had been shaved before, there was a chance that there would be ping due to the valves being closer to the pistons.

Well, with the head back on and the car and operational, i've noticed that when I put my foot down on the pedal, I can clearly hear pinging from the engine. My mechanic is on a 2 weeks holiday, but told me that if it needs shimming, he'd do it for free.

I just wanted to know if anyone has had any experisence with rocker arm shims and how effective are they?