Metric Mechanic S14 Engine Series chart e30 Magazines/Books/Booklets...

[Peter]

ST means Surface Turbulence: Metric Mechanic Patented Machined Grooves on

backside of the Intake Valves, Head of Intake and Exhaust Valves for the purpose

of increasing fuel efficiency, minimizes tuning problems, reduces detonation in the

motor, allows higher compression, and alleviates head cracking problems.