My '01 Formula and '04 GTO both did/do it if I get on it before reaching operating temp.
Short skirt pistons in an aluminum block = a bit more clearance when cold.
Nothing to worry about!
If it were a pushrod, it wouldn't go away when it warms up.
You really ought to take the Chevy out of there and put a RA IV in it!
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'66 GTO convertible. 462, KRE 290 cfm Dports, SD "Old Faithful" hydraulic roller, CVM ported aluminum Tripower, TKO600, Moser 12 bolt
"I open up three deuces, I'm Never Coming Back!"