The Jabiru version has a stainless steel tab on the plenum hooked to a hole on the most inboard cylinder fins. I have a loop of tie wire around the top cylinder bolts, and spring attach to that. After many overly complicated prototypes I find a simple version that can be rivetted to both sites seasy enough. Finding sufficiently springy springs was difficult. Made the tabs from 0.032" 2024-T6.
My eyeball vents have finally arrived, so I installed them.