Carb...not much if not adding weight. I do not have a scale to weight those light weigh parts. But the Carters are aluminum and the Holleys are heavy.
heads & headers...I should have read it all before I put the scale away. I have fully assembled J's and Edelbrocks on the shelf. 318 manifolds and hooker super comps (1-3/4 pipe) Give me a few minutes, I need breakfest.........
Probably add weight with the wrong covers. There not much anyways. Stock water pumps (Late modles, not early 60's or so W/P's) are aluminum. Starters can shave about (I guess) 10lbs or so depending on mini starter brand, but there all very close in size and weight.