The engine in my 2003 D2 was replaced several years ago, when my daughter was driving the truck and living in Maryland. Oil pump went, and there was a catastrophic oil starvation. Local mechanic sourced her a used engine with 30K fewer miles. I paid for the engines to be swapped. The engine runs solid. I have no idea what the actual motor come out of. I know that a bunch of the parts were swapped over from the old engine to the new engine. I have no idea which parts are original to the motor, or what vehicle it came out of. At the time, I did not know much about Rovers, and I don't remember what he said the engine came out of. He said it was a "better version" of the 4.6 motor than the one that was in it. It wasn't my car at the time, so I really didn't press him on the issue.
The truck is now mine again. I'd like to see if I can figure out exactly what was the origin of the motor. If it is just the same 4.6 that was in the 03-04 that's fine. I plan to build a bullet proof version over time, after I put it back on the road again post holidays. If it's a P38 bottom end, that would change my plans a bit.
How do I identify exactly what this long block came out of? Is there a way to tell if this was yanked from a particular Rover? Block casting numbers? Stamped serial numbers? Any real way to tell?

 

Apparently they was some color codes on the P38 blocks, Red is the best, yellow second best, blue is hte worst. I have had plenty of blue engine trucks with no issues.

 

There is a number stamped on the block deck that I believe you can use to identify when it was made and what model it came from. I think it’s drivers side just below where the head meets the deck.

 

Here is a snap I took of the S/N on the P38 block I'm currently running...

 

Where do we find these red/blue/yellow colour codes? And is that just a Bosch engine thing, or would I also find it on my P38 GEMS engine?

 

They describe the whole color code thing in the "How to Power Tune a Rover V8 engines for road and track" book...

Page 24 to 26: https://books.google.com/books?id=gm...20rover&f=true

Blue internal paint dab was lowest grade... Yellow then Red being the best...

Not to be confused with blue paint externally on the front of the block which is something different. You're looking for paint in the valley of the block. I couldn't see any paint at all in the valley of my block. long gone I guess.

 

So I would have to have the cylinder head off to see it?
Seems odd that there are no external casting marks like I have on my Fords.

 

No, you can see it with the head on, here is a pic with the engine assembled:

 

How are the numbers interpreted?

 

Here is one guide from the Rimmer Bros site...

https://rimmerbros.com/content--name...Engine-Numbers