Fitting a Rover V8 into an SE6 Scimitar...

(This isn't bible, it's just how I did it. There's all sorts of drawbacks but details like "Ooh, you don't have a spare tyre anymore" don't bother me. I'll never get a flat anyway. :-)

Remove and sell your old Ford V6 and Gearbox. I can't think of anything to keep off it, some people reuse the rad but read on for my solution.
Engine Mounts. I was luck enough to find that SD1 engine mount brackets, normal Scimitar cotton reel rubber mounts and the standard, unmolested chassis mounts all mated up fine. No cutting / welding whatsoever was carried out. You really can let a Rover V8 sit on the orginial (SE6 anyway) chassis mounts. Easy! OK, if you have a Range Rover or other donor then these may need modification but this should be minimal. Remember, just make it STRONG if you have to alter anything.
Making space - cutting the bulkhead. If possible get a bare V8 block and heads, bolt on a gear box and stick it in the engine bay, find out where it hits the bulkhead and make bold marks in marker pen. I cut 3 sides of a square(ish) so that I could fold the sides of the bulkhead into the footwells a bit (yes they get narrower but not by much). More room for engine, a little less for feet, you'll need fibreglassing skills here (Cleo did that)but it's not too bad.
- I cut pieces to fill the newly made gaps from existing fibreglass sheet of similar thickness to the body and held them in place.
- Mix up a little Isopon fibreglass filler as its easy for the novice and use it to "glue" the fibreglass in place.
- Now its secure get a fibreglasser to laminate over the area, inside and out to give it strength, surely you've got a mate who can do this if you can't?

Here's some info on fitting autoboxes »

Gearbox mounting. The Rover SD1 has a pressed "bullhorn" shape mounting, you need this. Cut off the ends AFTER the gearbox mount holes, atatch it to the box and jack it into position (make sure the prop / flang is high enough to clear the cross-member between the chassis rails!
- Hold the original Scimitar gearbox mounting plate in place below the SD1 mount, you'll see its about 2" nearer the rear of the car than before - tack weld it to the SD1 mount and mark out where the chassis rails cross it.

Summarised. There are lots of ways to bolt it up to the chassis, you'll find that if you can extend the plate you will still be able to use 2 of the original captive nuts in the chassis. Do this so that you can get in there without the jack holding things up.
I drilled through both the plate and chassis rail to mark where I needed new holes (I drilled 4 new ones for extra safety / strength.
Select a suitable bolt and nutsert combination, say M10. Nutserts by the way are like rivets but threaded up the inside, you can get them from tool hire places and shops. Drill the chassis holes EXACTLY at the stated size for your nutsert, it should be a secure push fit. Using the nutsert tool crimp it in place into the chassis rail.
Drill out the holes in your mounting plate to suit the bolt.
Check fit and securely weld up the SD1 mount to the scimitar plate and bolt it all in place.
[I will try to get a picture / diagram of this in place soon]

I mount a great big early Vauxhall Senator radiator up front - lots of cooling! It fills the whole void and is about twice the height of the Std Scimitar one. Use an SD1 expansion tank somewhere high as well.

Heres a pic:
(click to enlarge)
Oh yeah, get a one piece prop from Reco-Prop of Luton (01582 412110), all you have to do is tell them the gap between the flanges and what's connected at each end, i.e. Rover SD1 Gearbox to Scimitar Axle. about £150 later you'll get it in the post.

My 4.6 Rover V8 - it'll do for now...

The Scimitar started out with a Ford 3.0L V6... The thing is though, I had a 3.5L Rover V8 bought for about £50 off Stevie (click here to see his 4.0L V8 Capri) and well, you know, that 8 cylinder sound...

Cleo (he of great V8 wisdom) put a Hurricane cam and gearbox my way and with a bit of chopping, fibreglassing, welding etc. the Scimitar soon ran with the 3.5. At 155 - 170 bhp (plus being a bit old & tired) it never really cut the mustard. What it did do was prove that I could make the Shitimar work with a Rover V8...

...A friend of a friend sourced a brand new 4.6 Range Rover short engine at trade price, I found some brand new Real Steel heads, carb, Typhoon cam and other stuff, took it all into the workshop, clattered about for a bit and then wheeled this out:

4.6 Litre Rover V8
(click to enlarge)

[Note the spanking brown detailing courtesy of Stevie Coker - An acquired taste?]

The Rough Spec:
650 cfm Holley 4 barrell carb - Real Steel
Offenhauser 360 inlet manifold - Real Steel
Stage 2.5 ported, polished big valve heads - Real Steel
Typhoon cam - Real Steel
Cloyes Roller Timing Chain - Real Steel
Hi-rev lifters and adjustable push rods - Real Steel
4.6 litre lightened and balanced Range Rover V8 short engine - Powertrain Products
Water pump, P6 pulley etc - JRV8 (read about this guy, he's one of the best for parts and help)
Mallory Dual Point Distributor - Real steel
Magnecor Plug Leads - Msport.co.uk

Mark McKinlay has a V8 SE5 convertible(!), he's also got all the rover V8 engine numbers and gearbox numbers on his own web site in the technical section - you might find them useful, click on 'Technical'...

Here's some pics of the engine in build:
(click to enlarge)