Engine replacement - 3.5 to 3.9

[clbarclay]

The 3.5 EFI in my classic is officially dieing , half way over pheasent steps green lane I let the passenger drive (bad mistake i know :lol: ) and notice just how blue smoke the exhaust is putting out . Its still goes but its never run right :(  and the oil usage is now unaceptable etc. so the plan is to change it for a complete engine + EFI loom out of another RR (or disco).

How much time and trouble is it to replace a 3.5 with a 3.9 (or even 4.2, you never know) or should I just look for another 3.5?

Its going to be bolted to an ZF auto so I now a few small things like throttle linkages will probabply need changing.

Fuel lines/pump :?:
Cooling system :?:
Gerabox fitting :?:
Engine mounts :?:
Ancillaries :?:
Starter motors :?:
Anythng else i've missed :?:

[clbarclay]

OK just done a little search

Can you still use 3.5 exhasut with a 3.9 if so would it affect the engines output?

[Range Rover Blues]

Hello mate.

<===== that thing is a 3.5 body with a 3.9 lump (soon to be bigger I hope).

Let me see :?

Engine mounts, same
Throttle linkage, same I think
Exhaust, well the power hike from a 3.9 is partly due to the better/nigger downpipes and bore.  I'd suggest sticking with the 3.5 as it routes differenlty under the gearbox )you'd need the 3.9 crossmember) and gets damaged more.  I've fitted a 3.5 sports system.
Starter goes on the engine anyway
Alternator.PAS etc was on the early cars the same
Radiator is different, the 3.5 had an oil cooler as an option and it was external, the 3.9 had it as standard in the cold side of the rad.

The nuts and bolts should be easy, your worl will come translpanting the EFi, you need the whole thing but luckily the loom comes out in one piece, try to get the connector for it though and DO NOT plug in into the connector that supplied the 3.5 EFi, it needs the leads swapping round.

You might want to get the electronic speedo device for the EFi to work properly too.

Any questions jusy ask

[clbarclay]

Thanks

I expect i'll just find another 3.5 For the time being then to make life a bit easier (time is becoming a vuluable comodity at the moment for me), certainly if the wiring is going to be more than an out with the old, in with the new.


I expect a good 3.5 will easier/cheaper to find than a good 3.9 :?:

[Range Rover Blues]

Well there are folks who will tell you you're doing the right thing.  The 3.5 has something of a reputation for being the most solid V8 Rover built, all the following incarnations were modifications of the original design and that's when you start to hear about slipped liners etc.

Swapping the EFi isn't an afternoon's work, but you could do it at some point in the future, I think the Hotwire EFi is much more robust than what you have and it will work well on a 3.5, in fact if you tune the 3.5 then the 3.9 EFi will cope better with the mods, say a filter, sports pipe and maybe a mild cam upgrade