The pistons probably aren't made for spirolox, but rather a wire lock, aka Cosworth lock. If the bottom of the groove is radiused, it won't accept a spiral type lock.
Tnx B3; however the lock grooves are indeed squared; checked that out a long time ago. Being old Arias they were probably thinking of using Tru-arcs.
The Spirolox fit nicely in the groove about 90% of the way around. It is just where the ends lap ever so slightly on the step in the middle of the spirolox; if the groove diameter was just a tad bigger, it would all expand a bit and the ends would not bump onto the step, and would drop into the groove nicely. I may try to take a pix here shortly... you know, worth a 1000 words LOL
