Differences between the Rover 3.5 V8 and the Leyland 4.4 V8.

WarrenL

Active Member
#1
I'd like to narrow down the differences between the Rover V8 and its Leyland P76 4.4 litre sibling. Somewhere on the forum (I can't remember where), Chris York tells a story about the 4.4 litre being part of the original plans for the V8 when Rover took it over, but a difference in bore centres stopping the show due to limitations of the production line machinery. According to Chris, IIRC, it was left to the Aussies to put the 4.4 litre into production because they were building a new line and so the different bore centres didn't worry them. Now, I'm confused! Come in, Chris! Today I was talking to a bloke who was driving a late 70s Range Rover that has been fitted with an ex-P76 4.4 litre V8 equipped with the Rangie's original 3.5 heads. Surely this wouldn't be possible if the bore centres were different? Same chap also converted another one years ago that ran the P76 block and later RR heads and EFI. It was only while chewing things over later that some bells started to ring, else I'd have asked him more questions. Dammit.
 

KiwiRover

Active Member
#3
Bore centres (and bore) are the same as far as I'm aware, but the deck height of the block is different. As the Leyland block is taller, the heads are slightly further apart and the intake manifold is slightly wider but you can buy spacer plates to run the Rover manifold.
Basically, most of the bolt on parts are interchangeable. You can swap heads, rocker covers, exhaust manifolds, front covers, sumps, bellhousings, engine mounts, camshafts etc between the two. The main bearings are bigger on the 4.4 so you can't swap cranks without a lot of machining. Leyland also did away with the outer row of head bolts but so did Rover eventually. Someone once told me that the flywheel bolt pattern was different but I can't confirm that and the distributor may be longer but I could be wrong about that too. All the parts on the Leyland are quite different to the Rover but they all attach in the same way.
 

WarrenL

Active Member
#4
The deck height was the principal difference I was aware of, Al. But Chris's account of the 4.4's origins threw me off. A trawl of the internet reveals quite a lot of parts swapping undertaken between the two engines, mostly related in the 4WD forums where it seems that prior to the easy availability of 4.6 short blocks, the 4.4 was a popular basis for a Landie/Rangie conversion or upgrade.
 

GRTV8

Well-Known Member
#5
There are a number of P76 listings on Trademe at the mo . Is that whats prompted your thread Warren ?
Maybe looking to upgrade the old girl are we ?
Want to test out that new slush box eh , with a few tricks up front ?
Sorry have I let the cat out !!
Gerald
 

WarrenL

Active Member
#6
Actually, I have started giving some thought to possible future tweaks of the engine, but a Leyland P76 block doesn't feature among them. As I stated at the start of the thread (if you'd read it... sheesh Gerald! :roll: ), it was talking to the guy with the hybrid donk in his RR, then afterwards remembering Chris's story about the bore centres. Things didn't add up.

As for actual tweaks, it started in the last few weeks with a little dissatisfaction with my carburettors, which are much better than they were, but still a teensy bit dodgy. After the last tune-up (with a gas analyser, etc) the car is running quite nicely and I'm getting some decent mileage now, but it feels a bit underwhelming in the power department, there's a tiny hesitation noticeable about half the time on takeoff (a sticky piston?), and starting from cold the car is apparently running on only one carburettor until some heat percolates through (it sounds like a Vauxhall Viva for about two minutes). I figured that I should probably bite the bullet and buy the rebuild kits for the carbs as a winter project, but if I'm going to do that...

I'll start with "Lucky Breathes Easy" and move onto Stina's engine upgrade thread (all 24 pages of it) and then chew things over. The problem is, after the ZF project and the new wheels/tyres, I am right out of Rover funds, so I'll be chewing things over for a while yet.
 

stina

New Member
#8
WarrenL said:
I'll start with "Lucky Breathes Easy" and move onto Stina's engine upgrade thread (all 24 pages of it) and then chew things over. The problem is, after the ZF project and the new wheels/tyres, I am right out of Rover funds, so I'll be chewing things over for a while yet.
Warren , it's 23 and a half pages of banter , and about half a page of useful information , and a few afternoons work ! :LOL:
 

unstable load

Well-Known Member
#9
This from Wiki....
Leyland of Australia produced a special 4,416 cc (269.5 cu in) version of the aluminium V8 for their Australia-only 1973 Leyland P76. The bore was 88.9 mm (3.50 in) and the stroke was 88.9 mm (3.50 in), making it a square engine. The block deck height was extended and longer conrods were fitted 158.75 mm (6.250 in) between centres. This rare engine produced 200 hp (149 kW) and 280 ft•lbf (380 N•m) and although export (to the UK) versions were planned, the closure by British Leyland of their Australian operations in 1975 precluded the widespread application of this engine.
I wonder if that crank could be squeezed into the 3.5 block with shorter con rods....... :idea:
 

GRTV8

Well-Known Member
#10
unstable load said:
This from Wiki....
Leyland of Australia produced a special 4,416 cc (269.5 cu in) version of the aluminium V8 for their Australia-only 1973 Leyland P76. The bore was 88.9 mm (3.50 in) and the stroke was 88.9 mm (3.50 in), making it a square engine. The block deck height was extended and longer conrods were fitted 158.75 mm (6.250 in) between centres. This rare engine produced 200 hp (149 kW) and 280 ft•lbf (380 N•m) and although export (to the UK) versions were planned, the closure by British Leyland of their Australian operations in 1975 precluded the widespread application of this engine.
I wonder if that crank could be squeezed into the 3.5 block with shorter con rods….... :idea:
Shoosh , don't put ideas in Warrens head !!
He's gonna deny it anyway and then trot the project out as a done deal - full description and pics of the whole process , FOMAL
He's dropping the sump as I speak .
Gerald
 
#11
I wonder if that crank could be squeezed into the 3.5 block with shorter con rods....... :idea:
Not easily. The main journals on the P76 crank are half an inch bigger than the Rover ones and the crank is quite a bit meatier so you either need to turn down the journals significantly or line bore the block quite a bit and then relieve the lower crankcase in a few places for clearance. It has been done but the Leyland crank is apparently a bit weak anyway and can break if subjected to a lot of revs.
Basically, everyone stopped playing with Leyland motors at the end of the 90s because the 4.6 was a much easier solution.
 

WarrenL

Active Member
#12
rockdemon said:
Hesitation - try a thinner dashpot oil?
It's apparent just as you prod the accelerator the first few millimetres, either at a standstill (i.e. in neutral) or as you get underway with a very light throttle. As soon as the revs rise it's gone. Dashpot oil was the proper SU stuff, but it's possible Pat the tuning guy dumped it out and changed it for something else when he had the tops off to set the needles. I'll make it the first thing to eliminate, anyway.

Now guys... whoops, battery's about to die! Back later...
 

WarrenL

Active Member
#13
I forgot to mention that the wee hesitation only shows up about half the time, if that's a clue.

Gerald is entirely wrong. I'm actually going to solve the power problem with a brand new LS9 supercharged crate engine. It's a GM lump, so the car remains true to its heritage. I'm getting out the block and tackle as we speak, and I'll post pictures of my Rover 7000 as soon as I've solved the diff problem.

Now, to steer this topic back on course!
 
#14
The P76 crank ( 88.9mm stroke ) will drop into later 3.9 and 4.6 Rover blocks, with some machining required to the counterbalance throws to clear the block, but not the early 3.5 V8
The P76 flywheel bolt pattern ( PCD ) is different to the Rover, so you will need to source a P76 flywheel, or have one made and the P76 starter ring gear is wrong; but there is a Rover 156 tooth ringgear that will fit and can use the stock Rover starter
Using shorter small-block Chev. con rods, which need narrowing at the big end, Chev. 305 pistons and you are up over 5 liters displacement Not an engine you would rev. because of piston speed issues, but not one you need to either TVR rev limit their Rover stroker V8s which is good policy
Been there, done that

GW
 

GRTV8

Well-Known Member
#15
WarrenL said:
I forgot to mention that the wee hesitation only shows up about half the time, if that's a clue.

Gerald is entirely wrong. I'm actually going to solve the power problem with a brand new LS9 supercharged crate engine. It's a GM lump, so the car remains true to its heritage. I'm getting out the block and tackle as we speak, and I'll post pictures of my Rover 7000 as soon as I've solved the diff problem.

Now, to steer this topic back on course!
HaaHa - I knew it . You are up to no good . The whole P76 thing was just a red herring .
7 litres is going to be interesting in that little body . At least you've got the slush box to cope with the power .
Gerald
 

WarrenL

Active Member
#16
Anyway, I'm NOT, repeat NOT, planning a conversion using a P76 engine. However I can foresee a time when Brown Rover might receive a few engine mods. More power would be nice.
 
#17
Whilst surfing the net looking for some specific parts for my P76 V8 hybrid project I came across this posting.
Briefly I've owned and run a modified MK3 P5 coupe for nearly 30 years. Purchased as a tired, rundown vehicle I recommissioned it initially over a two year period re-engining it with a P76 V8. Other modifications took place over the years to improve it as a driver. It was my daily driver for 20 years before being retired to Club plates and a more leisurely existence.


The current under bonnet setup.

Original P5 MK3 BW35 case fitted with BW40 internals. It still retains the functioning rear pump.


The current P76 engine in place after a freshen up several years ago.


My project P76 hybrid engine. Modified P76 inlet manifold. Volvo CD Zenith Stromberg carbs. Range Rover air filters. Not visible but a custom adaptor has been fabricated to allow the fitting of a ZF4HP22 Jaguar XJ40 transmission. Range Rover reduction starter motor, Range Rover flexplate bolted to the custom adaptor.
NB. The P76 crankshaft flange is different to the Rover 3.5 V8 flange.
 
#18
For those folks that are interested in modifying or building engines here's a short video of the P76 hybrid engine's initial start. Obviously not tuned but with rough settings on both the timing and carbs.
This engine is also setup for dual fuel with the primary fuel being LPG. You may note that there's a TPS adapted to the engine (front PS carb) that will feed an LPG module and stepper motor (fitted behind the carbs) pertinent info. There's also an oxygen sensor bung fitted to the headers on the current engine on the car.
The Ignition currently on the car is a Silicon Chip fully programmable module (designed by John Clarke.) The ignition module allows for 2 independent fueling maps (LPG & Petrol.) The benefit is that any rpm and load point can be modified to suit the particular fuel being used. This is especially favourable if any pinging or detonation occurs with a particular fuel as it can be dialed out using a hand controller.

 

colnerov

Well-Known Member
#19
Hi, Very tidy P5 and engine build up on the test rig. I've not been on the P5 forum for a while, how's the Magnette going?

Colin
 
#20
Hi Colin, the Magnette is virtually mechanically all done and has been for a number of years. I need to replace a few aged rear leaf spring side rubbers on the passenger side but that's about it. It really is due for the engineer inspection but covid managed to put the brakes on that. I tend to get involved with other projects once the more challenging work of fabrication and engineering is completed and the P76 Engine and test stand above is one of those diversions.





 
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