If you have a Rover P5B V8 model like I do, you will probably love the car, but you could use more power. The original P5B engine is of the 3500cc variety. The good thing when it was first released was that it had a higher compression ratio than some of the later engines, but because the headers had smaller inlet and outlet valves, it still limited power a bit. The other downside was the problem that leaded fuel was not available so you have to keep adding leaded additives to the fuel, which many P5 owners know is a bit of a hassle since it’s always at the fuel station. with such a big engine.
My first trick was to replace the heads with heads from the Rover SD1 which with the larger valves and unleaded valve stems saved me the trouble of putting in the fuel additive each time, but I didn’t really notice a lot of extra power. The Rover P5B is a very heavy car anyway and I guess you are not supposed to drive it fast, but I was expecting a little change in performance. Then I added a Weber carb and switched the ignition to a Lumenition electronic ignition system to get rid of the old point system. This made a small difference, but the performance was not what I would call amazing.
Then I decided to rummage through my pockets, steal the piggy bank, and opt to install the 4.6-liter engine from later Range rovers. Now this engine is actually the same stock block as the 3.5-liter in the Rover P5, so it’s actually almost a straight change. If you keep the original P5 distributor then you should keep the same engine front cover because the oil pump teeth are different for each model. Other than that, everything is fine. The engine mounts are aligned and all the exhaust manifolds are put back together as before. If you’re trying to keep your Rover looking original, you can even use the original rocker covers so even the insurer can’t tell the difference. Until he drove it, of course.
How do you drive? Well, between the two engines it is like between day and night. You’ll be grinning from ear to ear for days. So if you have some spare bobs and need your Rover P5 kick up your heels and go. Your only option has to be the 4.6Ltr V8.