My ever faithful 90 is going to be treated to a 3.5 V8 in replacement for it's 200tdi (which itself replaced the original 2.5 turbo). Work won't start for a year or so, so I have time to collect all the parts I need. I have an engine, and I fitted an ashcroft re-con LT77 about 5 years ago (and so would like to keep this).

I would like to start with a standard V8 spec galv chassis - probably Richards. So my first of many question that google has so far failed to answer is; what bell-housing and input shaft will allow a 3.5 V8 to mount to a Defender LT77, and require no bulkhead modification? One from a V8-LT77 Disco?

I'm afraid I can't help with technical stuff, but my first Defender was 3.5V8 90 and it was awesome!

Good luck, sounds an awesome project! Keep us posted  James
MY2012 110 2.2TDCi XS SW Orkney Grey - http://www.defender2.net/forum/topic43410.html
MY1990 110 200TDi SW beautifully faded Portofino Red - https://www.defender2.net/forum/post743641.html#743641
MY1984 90 V8 Slate Grey - https://www.defender2.net/forum/post744557.html#744557
Instagram @suffolk_rovers

Thanks I will do a proper build thread when I start. I'm looking forward to that V8 soundtrack!

A 3.5 is a nice conversion. Mine is a factory built 3.5 with the LT85 and is a nice set up if slightly agricultural. 1985 factory V8 Ninety
1953 80in ex Australia
1955 Series 1 now owned by my son

Was the LT85 standard on early V8 90’s? Most threads i’ve read on the conversion are also converting to auto - usually lifting a complete engine and transmission from a Discovery or Range Rover. I’ve yet to find any info on keeping the LT77 ‘box. Although apparently an LT77 is the go-to gearbox when putting a Rover V8 into a kit-car.

The LT85 was introduced because the LT77 wasn't up to the job of a V8 in a Land Rover. Kit cars are a lot lighter and so less of an issue.

I'm pretty sure that the LT77 was used in the TRV8 but again, a much lighter car. Darren

2013 Defender 110 USW XS
2013 Discovery 4 XS

"You came in that thing? You're braver than I thought!" - Princess Leia

MY 110 USW BUILD THREAD - MY 200tdi 90 BUILD THREAD - Instagram: @landroveranorak

You’ll need an LT85, or a R380/LT77 in V8 spec with the correct V8 input shaft. And with Defender shifters, which means having it made up or adapted unless you get very lucky and find one (most V8 boxes come out of Discos). Then you’ll need a bellhousing to suit, the LT85 has its own type and fits V8s no problem but LT77 and R380 bellhousings to fit V8 are pretty rare. And they differ in length because the boxes & input shafts differ in length. I made that mistake.

You’ll then need to use the later wide gearbox tunnel, seatbox and floor plates in order to fit it underneath. Or suitably modify your 4cyl ones. And new propshafts too. Finally you will, depending on the age of your vehicle, potentially need to widen the tunnel in the bulkhead to suit. However that would give you a ‘factory’ setup

Alternatively you could leave the transfer box, gearbox etc. in the standard 4cyl position and use custom mounts for the engine. This would mean custom pipework etc. as well though that’s usually not a big deal. An LT77 should fit under the 4cyl tunnel in this position, but no guarantees with the other boxes. LT85 is a bigger unit.

Great, thanks Retroanaconda. Just the answer I was looking for. So if I understand that correctly, a Discovery V8 to LT77 bell housing and input shaft on my gearbox would allow the V8 to fit without bulkhead modification? Just the engine mounts and plumbing to sort then. Happy to do all the mechanical and welding work, but would like to keep it all related to one component. So all mods around the engine, leaving body and gearbox location standard (at least it seems to make sense in my head to do it that way).

Landroveranorak - I seem to recall the reconditioned gearbox I fitted is an LT77S, and so slightly stronger? This Land Rover will be relieved of all towing duties, and I’m not really into heavy off-roading so I’m hoping that the LT77 will stand up to the job.

If you use a Disco V8 LT77 (with shifters changed to Defender spec) then I think so yes. The bulkhead aperture is quite tight on the 4cyl (200Tdi and earlier) models and the V8 box would be about 2" further back than 'normal', however the V8 bellhousing is a lot longer than a 4cyl one and so the 'bell' bit of it is further forwards.

Unfortunately the only real way to know for sure is to try it.

Thanks again for the info 'anaconda. As you say, the only real way to know is try and see. Any photos of your build, or a build thread on here?

Interested in what you mention about the bulkhead aperture. I have just fitted a 3.9 with R380 into my 90 and bulkhead aperture is identical to tdi's and my TD5. The 90 it has gone into is a very early one.

I have changed the 'diaphragm' which is attached to the bulkhead though which I wonder if you are referring too.

You are quite correct with the other things you mention though. Only other thing I can add are a different radiator and hoses

Steve 02' 110 TD5 Double Cab
84' 90 3.9 V8 Caged Pickup Build Thread

Mobile Diesel Heater Build Thread

There’s a build thread on the LR4x4 forum, it’s a long way from finished though.

Some bulkheads have a changeable diaphragm which makes things a lot easier as you just fit one to suit the tunnel/floor you want, however some have a fixed welded on flange.

PumaPhil wrote:

Great, thanks Retroanaconda. Just the answer I was looking for. So if I understand that correctly, a Discovery V8 to LT77 bell housing and input shaft on my gearbox would allow the V8 to fit without bulkhead modification? Just the engine mounts and plumbing to sort then. Happy to do all the mechanical and welding work, but would like to keep it all related to one component. So all mods around the engine, leaving body and gearbox location standard (at least it seems to make sense in my head to do it that way).

Landroveranorak - I seem to recall the reconditioned gearbox I fitted is an LT77S, and so slightly stronger? This Land Rover will be relieved of all towing duties, and I’m not really into heavy off-roading so I’m hoping that the LT77 will stand up to the job.

The LT77s was fitted to factory v8 Defenders from 1991 to 1994 being replaced by the R380 if I remember correctly so it should be up to the task. If you get the bellhousing and input shaft for a v8 you can keep the current LT77 and just replace those giving you the factory position of the v8. 1999 Land Rover Defender 110 td5 station wagon
1998 Land Rover Defender 110 County Station Wagon ~ Sold
1995 Land Rover Defender 110 V8 Station Wagon ~ Sold
1985 Land Rover 110 ex mod project Tithonus ~ Sold

It won’t give the factory position of the V8 because the transmission is mounted in a different position in the chassis on early 4cyl vehicles. The engine would be about 2” rearwards from factory.

But easily worked around in terms of pipes etc.

Thanks both. Hopefully with the engine 2 inches further back it will still leave enough room to clear the bulkhead - I have read that some conversions mount the engine so far back that the rocker covers cannot be removed.