Leyland P76 Owners 2012

Retrospec of NSW P76 Sporting Club acheivements

SPORTING PNUTS AND THE V8

from the WA Westwords Sept 2012

WA Editor Sept 2012

2012 is a very important anniversary year for a number of P76 Owners Clubs.
N.S.W., S.A. and W.A. Owners Clubs all celebrate their 30th birthday this year but there
was another almost forgotten club that also would have celebrated its 30th birthday this
year, the Leyland P76 Sporting Car Club. This N.S.W. based club pioneered many of the
performance modifications to the P76 and its V8 engine. This story from “Dr Philthy”
Phil Crowther highlights those times and activities during the 1980s. Over to Phil.-

Phil Crowther highlights

It seems quite incredible that it is now nearly 40 years since the Leyland P76
arrived on the Australian motoring scene. It is also pretty amazing that we have had
Owners Clubs for the P76 operating since 1982. As a founding member of the N.S.W.
P76 Owners Club and an early member of the N.S.W. P76 Sporting Car Club I have had
many opportunities to witness firsthand how our P76s, which were relatively low tech
family sedans from the early 70s, managed to evolve and survive as useful and practical
transport during the last 30+ years. I have also witnessed how some dedicated Pnuts
have managed to achieve what most critics would have scornfully declared to be an
impossible undertaking, namely to take a mostly unloved and unappreciated “lemon” and
either lovingly preserve it or, as is more often the case, painstakingly restore it so that it
becomes an outstanding example of an Australian motoring icon.
I have been asked to write a few pages about our much loved aluminium V8
engines which were, by virtue of their light weight, a concept many years in advance of
the P76s contemporary rivals. Most Pnuts will of course already be aware of how our
P76 V8s are directly related to the aluminium Rover/Buick engines. Much of the history
of the development of the P76 V8 has already been covered in the 2 excellent books on
the P76 by Messrs Maloney and Farmer, so I won’t attempt to cover that ground again.
Instead let me entertain you with “Dr Philthys Condensed History of P76 V8 Engine
Development” as experienced by revhead Pnuts.
Once upon a time, when the only choices that most Australian drivers had were
either a Holden, Ford or Chrysler, or something European, Japanese or British,
somebody in the magic Kingdom of Zetland thought that it would be a good idea to
build an “All Australian” car using lots of good ideas from elsewhere adapted to make a
local car which would be better than the other locally produced offerings. Unfortunately
Araldite and Silastic hadn’t been invented in 1973 so a lot of little production faults (and
some other nasty factors) combined to give this new “wonder car” a very bad reputation.
A certain type of motoring enthusiast who was able to avoid the pitfalls of blind loyalty
to any particular brand of car was the sort of person who could appreciate the technical
merits of any vehicle which was more advanced and/or possessed a greater degree of
innovation than its rivals. Some of these discerning individuals eventually became proud
owners of Leyland’s greatest creation – our wonderful P76s.
With the creation of Owners Clubs, P76 owners suddenly had access to a
veritable gold mine of technical information to help them to keep their cars roadworthy.
Owners who had battled with repair or maintenance issues could draw on the
experiences of those other owners who had battled with and conquered the same P76
repair and/or maintenance problems. Then along came a bunch of revheads who were
sick and tired of having their Ps branded as lemons and who were determined to do
something positive to restore the reputation of the P76 and have it recognised for its
virtues rather than the stigma of poor production methods. One of these people was a
Mr Steve Maher who founded the Leyland P76 Sporting Car Club in late 1982. In
standard form the P76 was a fairly under stressed engine but when the boys and girls of
the P76 Sporting Car Club decided to put their P76s on the weekend racing circuits
around Sydney it didn’t take long to identify a few weaknesses in the V8s that didn’t
normally show up when P76s were being driven in normal road and traffic conditions.
7
Hard acceleration and braking on sealed race circuits often caused a loss of engine oil
pressure. The “Bodgey Bros” cure was to put extra oil into the engine to try to keep the
oil pickup covered, but the only really workable fix to this problem was to weld a series
of small baffle plates to the inside of the sump to limit how much the oil could slosh
around.
Club member Graham Redhead’s modification to cure this problem was quite a
stroke of genius. Being quite proficient with a mig welder he was able to fabricate a pair
of side tanks for the sump from sections of 50mm square steel sheet. These side tanks
were then welded on to each side of the sump. Holes were drilled into the side of the
sump first so that oil could get in and out of these tanks. From memory I believe that
Grahams “winged sump” needed about an extra 1.5 litres of engine oil to bring the oil
level on the dip stick up to the full mark and as far as I can recall after this modified
sump was fitted, Grahams P76 race/rally car never suffered oil starvation problems again
during its racing career.
The next problem we tackled was one which nearly every Pnut in the Owners
Clubs already knew about – cracking pistons. The standard P76 V8 pistons each had 2
big slots in the oil ring groove. These slots probably promoted a better flow of oil to cool
the pistons but the unfortunate result was that cracks frequently developed, and in
extreme cases, one half of the piston skirt would break away. Two nasty things started to
happen when a piston developed a crack. The first was that lots of nasty little fragments
would find their way down to the sump where they would eventually get sucked up with
the oil, past the mesh strainer on the oil pickup. Then they would get carried unto the oil
pump and merrily grind away at the oil pump gears and casing before getting caught
(sometimes) in the oil filter. The second nasty thing that happened was that a cracked
piston would start to carve nasty vertical groove in the cylinder wall because a cracked
skirt would allow the piston to kick out towards the cylinder wall and so cause nasty wear
on the thrust face side of the bore. Several different types of pistons were tried during
the mid to late 80s as we attempted to gain more power and reliability from our engines.
Some Pnuts fitted sets of oversized Rover pistons which at that time were quite
expensive and others tried fancy substitutions such as Volvo pistons. Most of our racing
engines were bored out to accept oversized Holden 173 pistons. Some machining work
always had to be done with this conversion. As the Holden pistons were sold in sets of 6
we had to buy 2 sets and get a workshop to select the 8 pistons which were closest to
each other in weight. These pistons would then need to be pin bored and honed so that
they would accept the larger P76 gudgeon pins. Before the gudgeon pins could be
pressed into the pistons all 8 conrods and pistons would have to be electronically
balanced. Often the bigend of each conrod would have to be closed and honed to restore
the bigends to perfect circles. One big advantage of using Holden pistons was that they
gave a slight boost in compression ratio and our racing experience showed us that they
were a stronger design than the original P76 pistons.
Often we found that our engines would start to misfire when pushed to the
upper limit of their rev range. The problem here was nearly always a breakdown in the
ignition. In simple terms there wasn’t enough spark at high revs. Graham, fellow member
Russell Nicholson, and several others cured this problem by fitting electronic ignition
systems to their engines. These systems, often borrowed from other types of vehicles,
proved so efficient and effective that we were often able to fit smaller jets to our carbys
without losing any power. Speaking of carbys, early in our racing adventures we realised
that the Stromberg WW carby which were standard for our V8, just couldn’t provide a
good mixture for engines which were being pushed a bit hard. Eventually nearly all of
our race cars were fitted with Holley 350s which, when combined with electronic ignition
systems, totally transformed the driving characteristics of our P76s.
8
Joe Torony, the founding President of the N.S.W. Owners Club, was one of the
first Pnuts to make modifications to the induction system to improve the power and
responsiveness of his V8 engine. Joe and his co-pilot, Paul Patten (also a past President
of the N.S.W. Owners Club), developed a method of filing away obstructions to the inlet
manifold to promote a better flow of the air/fuel mixture. Even though Joe and Pauls’
race car was a relatively low budget affair it was still an extremely quick and agile vehicle.
Joe also pioneered the manufacture of 2 types of very desirable items for P76 owners.
“Torony” extractors when fitted to any P76 V8 gave an immediate boost in performance
and through various motor trade connections; Joe was able to have rear sway bars made
which could be easily fitted to P76s to improve their handling.
In previous articles I have mentioned how during the early days the members of
the P76 Sporting Car Club were often subjected to a great amount of heckling and
teasing when they arrived at any of the Sydney racing circuits. However, within a few
months, that situation had dramatically changed because as we sorted out and eliminated
the bugs from our P76s our cars became more and more competitive and it was quite a
common occurrence to see 3 or 5 or more of our P76s lining up at the end of the days
racing to take part in the “Top Ten Playoffs”. Most of what we learned along the way
was also of relevance to P76 owners who wanted to improve the performance of their
normal street use P76s. To this end most of our racing mods were put on paper giving
our various club editors a much valued stream of new information to help their readers
get more enjoyment from their P76s.
In the late 80s and early 90s we started to become involved in fundraising events
for charities such as the Kidney Foundation and Camp Quality for kids with cancer.
Graham and Russell drew on their years of experience with the Sporting Car Club and
did an extensive ground up rebuild of a spare P76 shell. This car was eventually fitted
with a 5 litre engine with a monster Rochester 4 barrel carby and an electronic ignition
system that would melt standard spark plugs. It had a 5 speed Toyota Supra gearbox and
a modified Jaguar diff in a custom built cradle at the rear end. The boys fitted it out with
a full roll cage and rally seats and all the “bells and whistles”. Gas shocks on all 4 corners
took care of the bumps and the whole package was put together so well that on some
stages of some of the charity rallies nothing else could come close to this beast. Mind
you, Graham as a rally driver was pretty amazing too. He could flick a P76 sideways at
120kph along a dirt track that you could barely fit 2 fat pigs on side by side. I still think
he had some kind of built in radar or x-ray vision. It will be interesting to see if the
availability of the Range Rover 4.6 litre engines encourages more Pnuts to take up their
spanners again to put more P76s back on the road. I have been told that the 4.6 litre
Rover engines are bored out versions of the old 3.5 litre blocks. Maybe one day we will
get our hands on a damaged 4.6 engine and pull it to pieces to see what parts we might
be able to use to rebuild our old faithful 4.4 litre blocks.
In the meantime, if I was going to do a full rebuild of a P76 4.4 litre block, this is
what I would get done. When everything is stripped right down the first job is the block
bored out to suit the new pistons. The original steel cylinder liners can be taken out to an
increase of 40/1000 of an inch. Then;
• The top faces of the block should be machined or “decked” so that the new head
gaskets are sitting on fresh metal.
• The machine shop should supply and press fit to the block new camshaft
bearings.
• The old welch plugs should be removed and the block should be chemically
cleaned to remove any metal tailings and scale from the water jackets on each
bank of cylinders.
• All the threads should be cleaned and checked.
9
• The crankshaft may be machined. Usually most crankshafts can be taken down
10/1000 of an inch on both the main bearing journals and the big end journals.
The oil seal surface on the boss at the rear end of the crankshaft should be
linished to ensure that the rear oil seal works on clean metal.
• When new pistons are being fitted it is always a good idea to have the pistons
individually balanced and the connecting rods treated as previously mentioned
before the pistons are assembled to them.
• Additionally the front pulley should be dynamically balanced and, if the engine
will be mated to a manual transmission, the flywheel should be machined before
it is balanced and the pressure plate should also be balanced. One modification
we made was to drill and tap the flywheel so that we could use 6 bolts to hold the
pressure plate on to the flywheel instead of only 3.
• Heatseeker and Crow are 2 companies which can supply you with brand new
billet camshafts, timing gear sets and suitable lifters. Tru Roller is one brand of
timing chain and timing gear components. A roller timing chain is usually more
durable than the original w-link type. New billet camshafts are usually much
quieter in operation than original camshafts which have been reground or
reprofiled.
One very important item which you must check out when you are planning to
install a new sporty camshaft to your engine is the valve travel when the new
camshaft is providing more valve lift than the original unit. The valve springs
fitted to a standard P76 V8 cylinder head have a fairly fine pitch which limits how
far they can be compressed before binding occurs. If you have ever stripped
down a P76 cylinder head you will remember that when you used a spring
compressor to compress the valve springs, the spring compressor could only
squeeze the valve springs down a certain amount until the coils of the springs
were pressing against each other. When that happens it is known as valve spring
coil binding. When that happens the spring cannot be compressed any further
and if the camshaft is a high lift sports camshaft there is a danger that if coil bind
occurs it could directly cause excessive wear of the camshaft lobes and the lifters,
bending of the pushrods and/or failure or breakages of the rocker arms and/or
bolts/studs and pedestals not to mention the valve springs themselves. For that
reason alone most camshaft manufacturers’ supply a specification sheet with each
camshaft so that the installer can ensure that valve spring coil binding will not
occur.
• When it comes to reconditioning P76 cylinder heads it is best to leave the work
to a workshop that already has a good reputation but if you are tackling it
yourself;
The first procedure should be a thorough cleaning of the cylinder head followed
by pressure testing and checking for cracks. If the cylinder heads appear to be
sound then the usual procedure is to fit inserts to the valve guides or press new
valve guides into the cylinder heads. The face of the cylinder heads must be
machined and usually a full valve grind and decoke is done to each head to
ensure that there are minimal obstructions to the flow of the inlet and exhaust
mixtures and gases. We have previously used valve stem oil seals from petrol
Holden Gemini engines. These seals were a good fit on both the top of the valve
guides and the valve stems too. The small welch plugs at each end of the heads
should be replaced and if there is any doubt about the condition of any of the
spark plug threads then a heli-coil should be fitted. All manifold bolt threads
10
should be cleaned with a bottoming tap and it is also a good idea to make sure
that the 4 rocker cover bolts threads are clean and unobstructed by old gasket
cement etc.
• When the heads have been fully serviced the next item that requires some
attention is the inlet manifold. The standard inlet manifold as fitted to most P76
V8s is a good solid unit but like all mass produced items to some degree it has
been built down to a price rather than up to a higher performance standard.
Obviously there were serious limitations as to how much work and attention
each inlet manifold could receive on the assembly line. If you want to improve
your engines responsiveness there are several modifications you can make to your
inlet manifold to give your rebuilt engine a bit more power without
compromising its reliability.
Compare the dimensions and size of the inlet ports on each cylinder head to the
size of the matching ports on the inlet manifold. You will see that there is a
sizeable step. This step is what stops the P76 V8 from breathing properly in its
higher rev range because it causes an area or zone of turbulence as the fuel/air
mixture passes from the inlet manifold to each port of the cylinder head. By
eliminating this step you allow the mixture to flow more freely which directly
makes your engine slightly more efficient. Another area which requires some
similar attention is the raised boss where the carby bolts on to the inlet manifold.
It is almost a total waste of time fitting a Holley 350 to any manifold which has
not had the 2 inlet ports filed out. Compare the size of the bottom of the 2
barrels on a Holley 350 carby to the size of the base gasket from under a standard
carby. If the inlet ports on the top of the manifold are filed out to more closely
match the size of the barrels of the Holley 350 then you will achieve a greatly
improved flow of mixture into your new engine.
These were the improvements pioneered by N.S.W. Owners Club founding
President, Joe Torony. By improving the flow characteristics of your induction
system you are improving the charge density of the air/fuel mixture. This literally
means more mixture being allowed into each cylinder, giving a bit more power
for each ignition event and surprisingly improvements like these do not actually
cause any significant increase in fuel consumption, rather, by making the engine
slightly more efficient and smoother, quite often less throttle is needed for a
given power output and that usually equals better economy.
• Now, finally, a quick word about electronic ignition. Personally I have had very
little hands on experience with these systems but judging from the equipment
that’s being to all the late model cars I’d say that the way to go is to fit coil packs
to a new engine so that each spark plug is fed by its own coil. In terms of
providing each spark plug with the maximum possible power this may be the way
to go to make our V8s more efficient, more reliable and less polluting.
Hopefully someone out there in Pnut Land has already put pen to paper to tell
you all about developments in ignition technology. Are you there Garth? What’s the
latest gossip in spark technology? I hope you all enjoy the 14th Leyland P76 Nationals in
my absence. More of my rambling can be found from time to time in The Leyland Post
in my column “Philthy Suggestions”.
Phil (Dr Philthy) Crowther
Last updated
September 2012
This web site may contain Copyright material
If you find any problems with the site, please email the Web Editor