Excuse my ignorance. Never had a Chevelle with Cowl Induction.

Why are all the cowl flaps in the open position when parked? On the 69 Z/28, they only open when you floor it. Are the Chevelle flappers open by default?

They are vacuum actuated -- when car is parked and engine off, there is no vacuum so they are open. When engine is started, vacuum pulls em' shut. During WOT vacuum is minimal and the cowls flaps open for cool air.

PA tail code A/OA-10A…111 FW, Willow Grove ARS, PA, ANG/ACC

FT tail code A/OA-10A, HC-130P, HH-60G, A-10C…74th FG “Flying Tigers”, 75th FG “Tiger Sharks”, 23 Wg, Moody AFB, Ga

LN tail code F-100D/F, F-4D, F-15C/D/E, F-111F, HH-60G…492nd “Bolar Madhatters”,493rd “Grim Reapers”, 494th “Black Panthers” , 48 FW (USAFE), RAF Lakenheath, UK

P63 and P39

Plus there's a 2nd door inside the 1970-72 Chevelle Cowl Ind. Hood that opens electrically also to keep crap out when off,so it's system uses 2 doors,the Camaro only uses one.
Both the Camaro & the Chevelle use this same inner electrical door set up.
The Camaro doesn't have the outside Vacuum operated door.