Having found various posts on here re the mass of a Rover RV8 motor, which seem to disagree, thought I would weight the one I have in the garage.

It is a very early 3.5 motor from a P6, engine number 4550100886A, which was built between 1967 and 1976, according to www.rimmerbros.co.uk

The total mass, including starter (9kg!) , water pump, alternator, engine rubber mounts, inlet manifold and distributor came to 125 kg.

Note that the following were not included:

Standard Exhaust manifolds (5 kg each)
Flywheel to suit manual gearbox (14 kg)
Clutch (6 kg)
Carbs
Fan
Oil Filter
Oil
Water hosing
Water

So a complete motor with exhaust manifolds, flywheel and clutch but without other items mentioned above would weight 155 kg or say 340 UK pounds. (1 kg = 2.20462 pounds)

Cheers

Fred W B