Leyland Australia was even worse and no doubt, they were cobbled by orders
from the head office back in Britain. BMC had had a good line up of cars,
offering quite good alternatives to the cars of the big three. Despite
Australia being "American car" minded, BMC had a healthy market share when the
Leyland circus came to town. From then on, it was all downhill. The big
three all had good midsize cars and the Japanese were moving in with quality
small cars. Meantime Leyland continued to build plastic junk.
Some five years after the others had moved to midsize, Leyland launched
the
P76. Everything was against it. There is no doubt that it was both rushed
into production and the budget was lean. Plus Leyland's shocking track record
would indicate the brains behind the engineering, styling, finance and
marketing were not good.
The V8 motor seems to have been a cut-price compromise. The big three
ass
had quality proven iron block sixes around three liters and V8's of around
five liters. Leyland had neither. All they had for a six was a dreadful 2.6
liter OHC monster inherited from a previous design. It was badly engineered
and unreliable. For an eight, they had the Rover V8, which was intended for
the stillborn new big bodied Rover. At three and a half liters, it was a big
motor in fuel starved Britain, however in Australia, it was no match in
capacity or physical size to three hundred plus cubes of iron.
Plus, it was too British looking, with its SU's (carbs) and alloy rocker
covers, for the Australian motorists who wanted big Yankee street iron and not
pommy shit. ("Pommy" is the Australian word for British immigrants.) So,
Leyland decided to stretch the motor on the cheap. The original Rover sand
cast "A" series block was weak. Its bulkheads were thin and it lacked
webbing. This resulted in the regular loss of maincaps and the occasional
sleeve coming loose. This problem was addressed very slowly by Rover, even
thought they were well aware of it. A stiffer block did not arrive until
1976, some nine years into production and cross-bolted mains took until 1997,
a mere 30 years into production (you can't rush the British).
Leyland Australia simply took the "A" series block and raised it, to
accommodate a longer stroke and rods, no extra webs or thicker bulkheads.
They simply increased the capacity of a block, known to be weak, by 25%. Good
engineering or what? Now, as you may know, good alloy is light, poor alloy is
heavy. For instance, Asian piston sets are shiny and weigh a ton. Good
English "Hepolite" pistons are dull and very light. You may have already
picked up the P76 block and found it some 30 pounds heavier than the Rover or
die-cast Buick\Olds blocks. The blocks were in fact, so weak, that they
distorted on the assembly line, because they were hung up by one bank only.
This resulted in cars being returned to Leyland with blown (sucked inwards)
inlet gaskets. The dealers would measure the distortion with feelers gauges,
then machine the manifold out of true to fit.
The longer rods are interesting. The Rover\Buick 215 has a rod ratio of
2.01. A tad long for a street engine. The P76 at 1.78 is excellent. As rod
ratio was not was not a big issue back in the early seventies, I believe this
is pure coincidence and not good engineering. Leyland just wanted the motor
to look bigger. Either way, the long, thin rods do a good job, as I have
never seen one break or throw a cap in service. Down to the crank and its
bigger mains. Basically, the cranks are junk. They wear like butter and
break. It is possible that initially Rover sized the mains at 2.3" were tried
and the cranks broke during testing. A move to 2.55" could have resulted to
fix this. The 30% larger oil pump may have been added also as a result of
excessive main (bearing) wear during testing.
Up top, like the later Buick motors, the outer head bolts, which are a
design
error, are dropped. As the outer bolt caused Buick and Rover heads to tip
sideways, allowing head gasket seepage into the motor under the valley cover.
One might think that it was good engineering on Leyland's part to drop it. I
am inclined to think it was a cost cutting excersise. The "Chev type"
(Actually Olds) pressed rockers were without a doubt cheaper to produce than
the nice Buick\Rover shafts and alloy rockers. As for the pressed tin rocker
covers with plastic filler cap and single two-barrel carb. They certainly
cost less, but they made the motor look American again.
In service, the motors gave endless troubles. First up, new cars were
flooding back to the dealers with excessive oil usage or blown inlet gaskets
(or both). The inlet gaskets we have covered. The oil was simple.
Rover\Buick 215's do not require valve stem seals due to their rocker design.
P76's with their push rod oiled pressed rockers poured oil down the stems by
the gallon. A set of after market seals would fix this. I believe that later
factory cars were fitted with seals. Pistons began to crack next and in some
cases broke, destroying the engine.
Within eighteen months, it was all over. The ill-fated P76 ceased
production
and Leyland withdrew from Australia. Later as you know, despite government
assistance, British Leyland collapsed altogether.
Meantime, owners of used P76 cars found drive plates and starter
housings
were breaking. Plus engines were loosing oil pressure due to premature,
serious mains wear. Then cranks started to break and most secondhand cranks,
when checked, were found to be cracked. Performance wise the racing boys and
hot rodders buttoned strait onto the larger P76. All came away with long
faces and their tails between their legs. Broken cranks, sleeves coming
loose, cracked blocks and loose main caps stopped them all in their tracks.
So there you have it, the P76 is not a good motor. As I said earlier,
it
win, in my opinion, a cut price compromise to get a cheap, but interesting
motor into production.
Your main concern is the block and with 331 healthy cubes doing the
deed, you
may run into reliability problems. In fairness, we should note that a
commercial truck motor was also produced and called a "Boxer". Our knowledge
on this motor is limited. However, it ran different pistons of lower
compression and a "torque" grind on the camshaft. We believe there were other
modifications, which may have included a tuffened crank. Either way, the word
is that it gave good service. On the down side, a number of very professional
firms built performance road engines and they all ran into problems.
Basically, it was found that if a P76 was bored out and sleeved
(usually to
3.685" using.060" up Holden 186 pistons) plus the combustion chambers opened
up around the valves. Breathing improved immensely and the motors really came
to life. It would seem a bad valve shroud point occurred with the longer
stroke that did not occur with the 215.
In Australia, most of these "improved" motors were fitted to early Range
Rovers, where they got the daylight beaten out of them. In all cases, they
failed. Usually a sleeve came loose (block flex) or the crank broke.
Interestingly, main caps do come loose and number 4 is the usual offender.
However, the Rover 3500 is a worse offender, particularly in Range Rover
service. This would tend to indicate that the longer stroke and longer rods
subject the block to different stress points, when under load or revved
excessively.
One last point is that Repco (who were once Australia's biggest
automotive
parts manufacturer) got together with Phil Irving (designer and builder of the
Repco Brabham race engine) to build a Formula 5000 race engine based on the
P76. Upon examining the motor, Phil declared it unsuitable. However, Repco
was committed, so the project went ahead. Reliability was the killer and the
original heads restricted power for race use. A special pair of big port, big
valve heads were made. This left the block the only P76 item and this was
required to qualify for the Formula 500. Unfortunately, the block cracked
every time out. The project was declared a failure and the ultra reliable,
but heavy, Repco Formula 5000 Holden motor was reverted to.
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The rest later
Greg
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