I know Ron runs a 4.6.....what configuration do you have on your engine, Ron? i.e. front cover, etc.
Hi Stan,
I was thinking about you and your Rover as I drove to university yesterday. From my point of view, given the engine needs to come out regardless of what you decide to do, I would opt for a 4.6 replacement. My 4.6 was installed circa June 2007, and in the years that have followed, has covered some 153,000 miles (246,000km) of trouble free Rovering. The engine has been faultless, idle oil pressure at running temp is 30psi, just like it was when fitted. Apart from the normal consumables, the engine has not cost me a cent in that time. Sure it was expensive at the time, but so would rebuilding my original engine have been.
Configuration wise, I am running an SD1 timing cover with genuine oil pump gears, a P6B oil pump base. The distributor was at the time a NOS 35D8, with a wobbly drive replacing the original. It was re-graphed as the bigger engine needs less advance compared to the 3.5 to deliver maximum torque. I run it at 12.5 degrees BTDC @ 600rpm. The block is a Thor, top hat liners fitted, 8.37 : 1 CR. Dyno testing show that for automatics, the low compression engines are the better choice, as they deliver a greater percentage of torque at lower revs, making them superior to the HC engines up to 3000 rpm or so. My camshaft is a custom ground high torque - highway configuration, made in Australia.
Are there any negatives that the 4.6 has compared to the 3.5? No, in my view, the 4.6 is a vastly superior engine, the bearing caps don't come loose, the inside of the engine doesn't fill with dry dirt, the engine does not purge coolant in the way that the 3.5 always did. The 4.6 is a smoother engine in power delivery than the 3.5, the crank, rods and pistons have all been factory balanced to a far higher standard that that used for the 3.5. I love my 4.6, it has transformed my Rover, making it infinitely more enjoyable to own and drive. A couple of P6B owners have had a drive, and they say the feeling and sensation that you receive behind the wheel is fabulous.
If you decide on a 4.6 replacement Stan, I will offer all the assistance to you that I can. I know that you will not be disappointed. If you choose to go for rebuilding your 3.5, then again, anything that I can do to assist, I shall. Speaking from the position of having made this decision, I knew of no one who had done this to a P6B before, at that time. The Range Rover business that did the swap had not done one before either, my Rover being their first P6B engine upgrade. I read widely, sought different opinions, and then decided. I spoke to the gent who owns the Old Auto Rubber company in Melbourne. He had a P76 Leyland 4.4 litre V8 in his P6B, which he said was an incredibly satisfying transformation. He said the difference though was that his 4.4 would deliver more power, but my Range Rover 4.6 would deliver more torque. So the decision was mine to make. Now in hindsight, was it the right decision? Most certainly! Would I do the same again if I had the choice? Absolutely!!
All the best Stan,
Ron.