[p76rangie]

I also have a 4.2L that could use a refresh/rebuild (stock rebuild, perhaps a better oil pump and a Crower cam?) that I was planning on dropping in my RRC sometime in the future. Stock the 4.2 are supposed to make 200hp and with hot cam, the one I'm looking at claims a good torque increase.

The longer the stroke on a motor the more it is inclined to torque rather than revs. The 4.6 has a longer stroke of 3.2inches compared to the 4.2 of 3.03inches. Standard the 4.2 makes 200 hp and 251 ftlb of torque, whereas the 4.6 makes 225HP and 280 ftlb of torque.

So if you are after power and torque, the answer is obvious.

I have never had a 4.2, but I run 4.6's in a disco 1 and Rangie classic and they supply good power and torque. The earlier 4.6's in the mid to late 90's had issues with the block, but this was largely fixed in the later models. So try and find a motor that was made say 2000 or later.

 

[p76rangie]

I was initially more worried with a 4.2+ hot cam breaking the crank rather than the auto transmission, but I will definitely bear that in mind and maybe overhaul the trans and xcase at the same time.

Having looked around over the last couple of months, 4.6L Rover V8 seems hard to come by in my area without a $5G Range Rover bolted to it so unless a late 4.6 falls into my lap for a reasonable cost I'm probably going to need to go with my 4.2L.

As you only need a short motor (block, pistons, crank), check out the price of a new one. If second hand, you are better off buying one that is running in a car so that you can here it, or one that you know has come out of a wreck. Buying a secondhand motor by itself is too risky as you do not know why it was removed.

http://www.johnealesroverv8.co.uk/18.html