Hi all, I'm beginning the rebuild of the 3.9 EFi from my Discovery 1. I'm rebuilding the entire car as a 100" series/defender "hybrid" and for peace of mind I thought I'd strip the 96k engine block (which was running fine when it was SORN'd in 2011) and rebuild with new bearings etc. I'm glad I did strip it, as the big end and main bearings were badly worn, along with the camshaft and some bad scoring on the crankshaft journals.

Since I probably need to replace/regrind the crankshaft, I thought I might aswell see if I can get my hands on a 4.2 crank and along with a few other bits, rebuild the engine as a 4.2. The problem here being that 4.2 cranks are like hen's teeth! It seems that in the past, some engineering shops were reproducing these particular cranks and I just wondered if anyone knows where I might find one?

If anyone has done this conversion let me know if there's anything else worth considering

Cheers!

PS. Attached some porn below

I might be talking through my ar.. but is that amount of bottom end wear normal at less than 100k ?
I don't really know much about 4.2 cranks, other than they have been known to snap & that they were left overs from the cancelled LR/Perkins 'iceberg' project.

FWIW 4.2 has a different cam as well.

The 4.2 has the crank off the Project iceburg project, and is cast..

So no real benefit over a 4.6 crank or heck even the 4.0 crank..

Don't know how much you are wanting to spend, but here is another option:
http://www.britishv8.org/Articles/Affordable-Stroker-V8.htm

I have to admit, I was pretty disappointed with the amount of wear after less than 100k miles...but it seems it's not entirely uncommon with the Rover V8.

With regards to the 4.2 crank, it is my understanding that it will fit into the 3.9 block with just changing the pistons for low compression 8.13 pistons with about 30/40 thou skimmed off of them. There would be no machining of the head etc. Also, as far as I know the H180 kent cam works with both the 3.9 and the 4.2 engine, so I figured that upgrade would be sufficient (unless I'm mistaken). I think to turn it into a 4.0 (why bother?) or 4.6, there would be quite a bit more money to spend on machine work. So the theory behind stroking it to 4.2 was quite honestly that it would presumably be most cost effective and require the least amount of major surgery.

Thanks for the link 300bhp, I don't want to break the bank as the car will be much lighter than it was with the discovery body anyway, so there will be a performance increase and as long as it can happily tow along a decent sized trailer it will be ample.