Rover V8 ID numbers

[Moderator]

I took these snapshots (below) the other day to illustrate an old article for the archives about identifying Rover's by their engine i.d. numbers. The article isn't formatted-up yet, but I thought you guys might enjoy the photos.

And you might be interested in a couple quick weight measurements I took:
1a) stripped-down Rover 4.0 block with 4-bolt mains (x5) and bolts (x20) - 76.0#
1b) stripped-down Buick 215 block with 2-bolt mains (x5) and bolts (x10) - 73.0#
2a) stripped-down Rover 4.0 head (i.e. no valves or springs) - 17.0#
2b) stripped-down Buick 215 head - 15.6#
Note: the Rover 4.0 uses four fewer head bolts per side. Its valves are slightly bigger, as are its exhaust ports.    

I thought there'd be a bigger weight difference between Buick and Rover blocks.






(Later Rovers use a cam retainer, which mounts here.)



all photos copyright British V8 yadda yadda yadda

[Moderator]

One more photo...


(Compared to earlier engines, the 4.0/4.6 have really fat webs across the valley but the bosses for the extra head bolts have been eliminated.)

[BlownMGB-V8]

What is that round cover opposite the starter opening?

Jim

[Moderator]

I don't know what its original purpose was... but apparently at some point they started placing a Hall effect (crank position) sensor in that spot for the direct ignition system. When I picked up this block, the sensor was missing, but there was a sheet metal tone wheel riveted to the front of the flex plate.