Building a hybrid 90/110-Series/Sherpa 2.5NAD engine to fit a SIII per

[twodoorgaz]

Hi folks,

I'm hoping for some pointers here.

I will soon have to start preparing an engine for my chassis-up restoration of my SIII and I would like a 2.5NAD I also think this would make an enjoyable little project.

This engine will be freshly built on my engine stand and any necessary machining work will be carried out by my local machine-shop. I like to source my engine parts from Turners.

I'd like to prepare a 2.5 NAD that looks like a 2.25 5mb diesel and fits the same way using the same pedals, hoses, mounts, etc.

Its important to me that this uses Land Rover parts wherever possible and also that it fits without cutting the chassis (I don't mind losing the battery tray if needs be though). It would also need a vacuum outlet to power my brake servo.

I have absolutely no problem with breaking a few donor engines to get the right combination of parts - I've got plently of time and space to do this and already have access to two of the three engines.

I'm aware that this has been done before (I understand that Mr Hancock has done a few to great effect) and was hoping that forum members would be kind enough to help me prepare a "recipe" for the right engine.

So far, I've come up with this (predominantly thanks to the posts by Phil Hancock on various forums):

• 2.25 (10j) engine mounts onto standard chassis mountings
• Sherpa (or maybe FX4 taxi) cylinder block (14j/15j?)
• Ninety/One-Ten (12 or 13j?) (cylinder head, pistons, rods, crank)
• after this I get confused - I think that in order to keep the engine mounts original, I either need to:
  • stick to the sherpa pump/belt and cover (which I don't want to do as I'll need the ability to wade and don't fancy the rarity of the parts)
  • OR revert back to a timing chain by using:
    • the chain and tensioner from 2.5 petrol (could someone confirm this?)
    • the skew gear assembly, quill shaft, injector pipes, timing case, water pump, bottom pulley and injection pump from the 2.25 5MB diesel.

​I'm sure it will all make sense as I come to build it, but I'd like to gather the parts needed in advance.

Many, many thanks for any help you may be able to offer.

[Snagger]

If you're set on it looking like a 10J, then I'd go with your option of transferring the 10J ancilliaries to a 12J or fitting a 12J crank, pistons and rods to a 5mb 10J.

[secondjeremy]

You can build a 2.5 with the 2.25 timing chain and pump. I'd keep the 2.5 head with the block as it'll keep the compression ratio correct - use the 2.25 head and it'll be higher. (I know that the face is flat - but the ratio will take into account the comet combustion chamber in the head.)

Strictly the pump won't be calibrated correctly but you may be able to undo the max fuel control (throttle stop) a bit without causing black smoke.

[Snagger]

The injectors and swirl chambers are the same on the 10J, 12J, 14J, 15J and 19J.

[Phil Hancock]

The swirl chambers are the same on the 10J, 12J, 14J, 15J and 19J.

Wrong, the chambers are a larger outside diameter on the 2.5's plus the location peg is in a different position.

[Phil Hancock]

A 2.5 timing chain set will fit but the oil way in the block will need unplugging to supply the chain tensioner.

Fitting 2.5 crank, rods and pistons in a 2.25 block wont work as the 2.5 block has no oil jets for the pistons and using 2.25 rods wont work either as the oil squirts on the 2.25 rods is insuficient and the pistons will nip up in the bores. I found that out the hard way.

The skew gear will need changing for the 2.25d item