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Is it a ‘P300’ or a ‘ZX76’?
Or is it
a ‘Pissan’ ?
To start with...
This article was
originally written for a small car club magazine. The car club
editor posted it on the net at this address, purely as a reference for
club members. Apparently, a number of other people have accessed
this address, after doing searches for 'alloy V8
conversions'. I apologise to those people for not tidying
it up sooner.
I am in Australia. The P76 you will see mentioned in
this article was built here during '73-'74. Less than 19000 were produced.
The V8 version used a 4.4 litre all-alloy V8 which was derived from
the Rover 3500 (same 3.5" bore, but stroke was lengthened to 3.5" from the
Rover's 2.8"). I understand the Rover was in turn derived from a
Buick/Oldsmobile alloy V8 engine.
In Australia we drive on the left
side of the road. Consequently, the steering wheel is on the right side of
our cars. The P76 starter is on the right side also, making things a
bit tight there. If you are putting this style of engine in a
left-hand drive car, you may find things easier than I
At the end of 1996 I wanted to try a
different type of car. I bought a 1985 model Nissan 300ZX (Z31 series)
from a guy in Sydney. He had bought it for his son. His son didn't
want it, so it was left in the garage to run out of registration. The guy
then bought his son a brand new Corolla and had to dispose of the
Because the car was unregistered and had an electrical
problem, I got it for a good price. I took it to my Mum and Dad’s (Jessie
and Wal’s) house and a few days later I had it ready for rego. I soon
started calling it ‘The Cockroach’ because I thought it looked a bit like
one with its half closed, flip-up headlights.
I greatly altered it
about 18 months later, but originally it was a fuel injected 3 litre V6
with auto transmission, air conditioning, power steering and cruise
control. The colour of the body is what’s commonly called ‘Champagne’
(although if I was offered a glass of champagne that colour I definitely
wouldn’t drink it). It has a glass targa roof and the interior has a nice,
two-tone, dusty beige finish in velour. The build quality is
Apart from the electrical problem, the car was a good,
clean, straight and original unit when I bought it. Even over the longer
term it was a very nice car to own and seemed to have almost everything I
wanted in a car. On the open road it was quite OK, having an overdrive (of
sorts) on the transmission, four wheel disc brakes and independent rear
end, however its acceleration was very sluggish.
Much seems to have
been said about the handling of the Z31 300ZX in standard trim. It’s all
subjective. It stuck to the road better than most cars but by sports car
standards it felt relatively heavy and it understeered a lot. When pushed
very hard through a corner, it’s transition to oversteer was quite
The workshop manual says that the standard car weighs 1360
kg, but I am inclined to think that it is closer to 1400 kg in reality.
This is fairly heavy to us that are accustomed to the P76, which weighs no
more than 1270kg, fully optioned.
In mid 1998 the auto transmission gave up and was going to
be costly to replace. Since I had to spend a lot of money on the car, I
saw it as an opportunity to improve the performance. I looked at other
engine and transmission options:
- Imported Japanese engines in multi-cam and turbo charged versions
were complex to install (some with as many as 15 “appliances” to be
mounted in engine bay), computerised (which didn’t suit me), required
premium unleaded fuel (expensive to run) and still required an
engineer’s certificate after installation. The turbo alternatives would
have been very expensive to insure. Also, most of these options were
cast iron engines and therefore, heavy. The best of these imported
Japanese engines, I believe, would be the Lexus 4.0L alloy V8. Thanks to
Chris Dale for his advice on various options.
- American cast iron V8’s (and their Australian descendants) were too
heavy for what I wanted.
- Non computerised, alloy V8’s: There is a Toyota V8 which I
would have had to buy from Melbourne before even trying it (no thanks).
There is the Rover 3500, but why bother when you can use the P76
V8? I had a spare one and the more I looked and measured, the
surer I was that I could make it fit into the 300ZX. It became
something of a personal challenge.
For me, the P76 V8 was the best option because: it’s
light; I had it handy to measure and try for basic fitment without cost; I
had access to a non computerised, inexpensive transmission that was proven
to work with it (Borg Warner); it was easily convertible to LPG fuel; it
did not require a computer (I prefer it that way); it is cheap to
maintain; I’m familiar with it; comprehensive insurance for the package
was relatively inexpensive; I’ve got more pride in it, being a P76 fan;
etc, etc, etc.
Getting the engine/gearbox position correct was very
important. The drive line through the crank and gearbox should be parallel
to the drive line through the diff, within a tolerance of 1 degree, so
that there is no vibration. However, with an independent rear end, it
should not be in direct line with it, as this doesn’t give the uni joints
on the tailshaft a chance to move and lubricated themselves, I have been
told. (This problem would not arise where a live rear end is used.)
took a long time get the engine/gearbox position correct. I used a spirit
level, square, tape measure, ruler, string lines, trolley jacks, car
stands and numerous chocks and shims. The job was made harder because the
sump would not fit in its original form and had to be modified during the
I had to chop a section out of the sump so
that it would clear the steering rack, which is mounted behind the
crossmember in the 300ZX. I made a custom oil pickup to fit and added a
wing to the side of the sump to restore normal oil capacity.
the original starter was hitting against the intermediate steering shaft.
When I was having trouble with this Chris Dale showed up and suggested a
Rover starter, which has the solenoid beneath it instead of on the r/h
side. Unfortunately the Rover solenoid was too long and it the fouled on
the steering rack, but thanks anyway Chris - it got me thinking along
other lines. Thanks also to David Waters, Russell Nicholson and Garth
Morris for advice on starters.
I found the ultimate solution at
Adamstown Auto Electrics (Newcastle). Kevin, the owner, was terrific. He
trusted me to bring home and try 2 new starters. The Lucas LRS196 for some
of the Land Rovers (and Range Rovers?) is the same layout as original,
with the solenoid on the side, but very much smaller overall. It is much
more powerful, being rated at 1.4 kW, but the main reason I liked this
alternative was because there was no cutting, filing or welding required.
I simply had a ring made up (for $20) to enlarge the diameter of the
locating lip. It’s a beautiful little starter, and although labelled as a
Lucas, it’s apparently made by Magnetto Marelli.
The original oil filter would have hit the sway bar. Russell Nicholson
had previously converted an oil filter housing for me to take the Holden
Z30 filter (That's a Ryco part number). Thanks again, Russell. After some
investigation, I discovered that the small Z160 filter for the late model
V8 Holden Commodore has the same seal and thread size as the Z30. This
meant that it screwed straight onto my converted filter housing and fitted
beautifully in the small space.
Russell Rygrok did a great job of
putting together an indestructible automatic transmission for me. At first
glance it looks like the original Borg Warner 35 from the P76, but it has
a Ford Falcon XD case, late model Mitsubishi Sigma (Borg Warner model 40)
internals, some 6 cyl P76 parts and some V8 P76 parts. Thanks,
It took me three hours just to get the auto trans dipstick
tube bent to the right shape and mounted so that it clears the
I fabricated engine mounting brackets and a gearbox
mounting/crossmember to bolt to the original holes in the Nissan. I used
the common Ford Falcon rubber gearbox mount. Tacking the engine mount
brackets together ‘in situ’ was an incredibly awkward
Throughout the project I refrained from making structural
changes to the car, altering original parts or cutting up wiring harnesses
where I could so that in the future, with an original style Nissan engine
and transmission, the car can be quickly and easily restored to its
original form. I have stored away the unused original parts for that
I used the original Nissan power steering pump by making a
mounting bracket to go on the top r/h side of the P76 V8, where the air
conditioning pump is normally mounted. A Mitsubishi Colt heater hose
currently connects the pump to its reservoir. I haven’t sorted out the air
conditioning yet, but to do this I may have to remount the power steering
pump and extend the hydraulic lines.
I was able to retain the
original Nissan radiator. It simply needed a proper clean out at a
radiator shop and proved quite efficient. It is mounted at its standard 45
degree angle, leaning forward in the 300ZX, and has 2 thermatic fans on
it. The harmonic balancer on the V8 clears the bottom tank by about 13mm.
As a matter of interest, the radiator hoses I am using are bits cut from:
Ford F100, Mazda RX3, Torana 4cyl and P76 V8.
It took a full day to
make the complex r/h engine pipe, and a total of three days to sort out
the exhaust system.
The original tailshaft (drive shaft) was a two
piece affair with a rubber bearing in the centre. In keeping with my
‘non-butchering’ plan, I saved the original and got a Nissan Nomad (van)
tailshaft with the same rear flange and had it cut and altered for the
The speedo cable had to be custom made with a Borg Warner
gear on the drive end and a Nissan fitting on the speedo end. The P76
drive gear has 18 teeth, the Sigma one has 20 teeth and I used another
with 22 teeth that I got from a transmission place. As a result, the
speedo now reads correctly.
I made adaptors for the Nissan oil
pressure and water temperature senders to fit on the P76 engine, so the
Nissan gauges read correctly.
There are a million other little
things like that to do in this sort of conversion, and they take up an
amazing amount of time. For example, sorting the auto trans gearshift arms
so that the ratio is correct and the transmission is in exactly what gear
the shift markers indicate. Similarly, the ratio of throttle pedal travel
to carby operation and auto kick-down cable pull is important.
Following is the specifications of the camshaft I am using. I recommend
it for LPG conversions to P76 V8’s. It has a smooth idle and seems to have
good low end torque, but also delivers a good increase in horsepower
through the rev range. It’s a beauty.
The car is now considerably lighter in
the front end, so much so that it sat 20 to 25 mm higher on the front
suspension. I put a pair of lowered King’s Springs in the front to sit it
back down again. Even before the lowered springs went in, it was obvious
that the lighter engine made a huge difference to the way that the car
handles. It has lost all of its understeering tendency, turns quicker,
stops better and generally feels a lot more nimble on the road. It’s not
only safer but also a lot more fun to drive.
Acceleration is quite
brisk, but this is partly because the diff still has its original 3.7 to 1
ratio. I’m hoping to get hold of a 3.3 to 1 diff centre from overseas,
which will lessen the punchy acceleration, but make the car cruise more
easily on the freeway.
Comprehensive insurance quotes for the Z31
300ZX are interesting:
Converted to V8
It now costs me only $68 more per year to insure the car as a V8.
Big deal. Interestingly, Shannon’s can also provide inexpensive ‘Laid up’
insurance coverage for stored, unregistered cars.
Having fold-down back seats and a
lift-back, the 300ZX is very practical and carries quite a lot. There’s
plenty of head and leg room in the front for tall people. The glass targa
tops are, of course, removable and although they have to stored away in
the back, it’s well worth the bother. It makes the car very enjoyable in
The conversion took a lot of time and effort but to me it
was worth it. I now have an ‘alloy V8’ powered sports car that is very
comfortable, looks really nice, accelerates, rides, handles and brakes
very well, is cheap to run, easy to maintain at home and is affordable to
insure. And in dollar terms this can be done for less than the cost of a
Hyundai Excel. Although there are still a few things to sort out, I’m
really happy with it.
There is an incredible amount of time consuming ‘mucking around’ in a
job like this. I’ve kept my description brief in this article. I hope
other club members still find it interesting.
A big “Thank you” to
my dad, Wal and my mum, Jessie. They gave me lots of assistance and had
heaps of patience.
Soon I will publish an update/addition to this article. The car
has travelled nearly 80000 klm since mid 1998 when I did the conversion.
It has been quite reliable, which is just as well because I use it
as a daily driven 'hack'. No shudders or broken engine mounts -
which would have indicated mis-alignment of drivetrain. Cheap to
run, but the biggest benefit has been in the handling and braking due to
having less weight at the front. It's as if I hit on the perfect
formula with the lightweight all-alloy engine in a