If you own a Rover P5B V8 model like me, you probably love the car but could do with more power. The original engine in the P5B is of the 3500cc variety. The good thing when it was first launched was it had a higher compression ratio than some of the later engines, but because the heads had smaller inlet and outlet valves it still limited the power some what. The other disadvantage was the problem of leaded fuel not being available so you have to keep adding lead additives to the fuel which many a P5 owner knows is a bit of a pain as you are always down the fuel station with such a big motor.
My first trick was to replace the heads with heads from the Rover SD1 which with the bigger valves and unleaded valve stems saved me the job of putting in the fuel additive each time but I didn’t really notice much extra power. The Rover P5B is a very heavy car anyway and I suppose your not supposed to drive it fast but I was hoping for a little change in performance. I then added a Weber Carburetter and changed the ignition to a Lumenition electronic ignition system to get rid of the old points system. This made a bit of a difference but the performance was not what I would call startling.
Then I decided to dig deep into my pockets, rob the piggy bank and opt for fitting the 4.6 ltr engine from the later Range rovers. Now this engine is really the same original block as the 3.5 ltr from the Rover P5, so actually it is nearly a straight swap. If you are keeping the original distributor from the P5 then you have to keep the same front cover from the engine because the oil pump teeth are different for each model. Apart from that everything goes in nicely. The engine mounts line up and all the exhaust manifolds go back together just as the old one. If you trying to keep your Rover looking original, you can even use the original rocker covers so even the insurance man couldn’t tell the difference. Until he drove it of course.
How does it drive? Well, between the two engines is like between day and night. You will be grinning from ear to ear for days afterwards. So if you have a few spare bob and need your Rover P5 to pick up its heels and go. Your only option has to be the 4.6Ltr V8.