February 27, 201114 yr Author comment_347491 Hi Brian.....They are valve reliefs cut in the top of the pistons. Yes you've got the same set up as Chris, but you've got the big chamber E88......I've got the small chamber E31. Link to comment https://www.classiczcars.com/forums/topic/38706-73-piston/?&page=2#findComment-347491 Share on other sites More sharing options...
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