Have you weighed a Gen III Hemi? From what ive read of other people it weighs about the same as an aluminum headed 383/400 Big Block. Quite a bit more than an LA motor.
Not true. A 340 bare block weighs ~160-170 lbs. a 5.7-6.1 hemi bare block weighs 165 lbs. And a 440 bare block weighs ~225 lbs.
You're looking at about 450-500 lb for a fully dressed hemi. Block is 165, 6.1 crank is 10 lb heavier than the 5.7 at ~65, short block weighs 250-300, heads 70, etc.
I would say an aluminum headed LA would be right at the weight of a 5.7/6.1 hemi, and a Aluminum headed RB would be ~55 lb heavier.
Here are some iron headed weights from Moparts tech archives:
