The 3.9's, 4.0 and 4.6's can suffer with leaking cylinder liners. Its a well documented problem. Be very careful of anything that "only uses a little water"
The 3.5 does not have this issue. So buy carefully.
If you go for a 3.5, then get one after 1982 (Check the year, as Im not exactly sure) as it had the revised block design, with stronger webs across the block and a stronger rear end around the crank area.
Dont get a P6. Whilst they are OK, they have the older rope crank seals, smaller oil pump, weaker block, poorer cylinder heads etc.
One form a post 9182 SDI would be good.
Here is a useful site for Rover V8 Engine numbers. Well worth looking at before parting with your cash.
LINKY
Having said that, you get more power and torque from the larger engines. Whats more, my Viento managed 0-60 in 5 secs dead. Several other Vientos with RV8's have made simlar times. Its plenty fast enough for the road.
Tuning any RV8 for a lot of power is very expensive. A Ford 302 or similar will give you more power, for a lot less money. Downside is they are a bit heavier. But ford parts can be cheap.
Consider your brakes and suspension as well if changing your engine.
Also check out paul at www.V8tuner.co.uk (good bloke, good prices)
http://www.v8tuner.co.uk/faqs.php
and
http://www.v8engines.com/faq.htm (interesting bit on the colour of the inside of the engine, ie silver, brown, black. Its a good rule of thumb when buying.
WALK AWAY from anything that is black inside regardless of how cheap it is. (Been there and done it, see pics below) Unless you are going to use it as a part exchange!
Stripped Head in the Garage
Slightly Worn Bearings
Hope that is of some help.
