There must be a file size limit that I don't know about, 'cuz this thing
doesn't get anywhere when I send in one piece. I've broken it in two
parts, sorry for the length!
An article I wrote for my local car club newsletter:(1995)
Well, it's been awhile since I've seen most of you, and of course you
shouldn't assume that I've lost interest in British cars, in fact, quite
the opposite is true. When I left Medford for art school, I drove away in
what turned out to be a wonderful little 1976 Datsun B210 4dr. After four
years and 55,000 miles, it had proven to be as reliable and durable as it
was slow. But, the morning of December 7, 1994 I woke up to find that the
B210 had been swiped right from our apartment's parking lot! Also, in the
trunk were all the tools I had managed to scrape together over those four
years. Two weeks later there was still no sign of it, and so insurance
company issued me a settlement.
I had been looking to replace it with an early 70s Datsun 510, which can
be a very nice little car, but there weren't any for sale. I needed
something that I was fairly familiar with at some level, something rather
simple and easy to work on, etc. So, I decide to check out some of the
many 240Zs that were for sale.
I ended up with a 1973 with 105,000 on the clock. The interior is in very
nice shape, and the motor seems to run pretty nicely. So I thought that it
would be interesting to give you a comparison between the 240Z and my TR6,
which is also a 1973 model.
It's obvious that the Z was designed to compete with the TR in the sports
car marketplace... the platforms are so similar. 2.5 liter inline 6, twin
sidedraft carburettors, four speed gearbox, independent rear suspension,
two seats. Even the proportions are very similar, although the Z is a bit
wider and longer. The driver of either car is nearly sitting on top of the
rear axle. Yeah, OK, the Z isn't a convertible, and the TR is built on a
separate chassis.
The Z engine is huge! Thought the displacement is very much the same
(2399cc for the Z and 2498 for the TR) the motor is, I'd bet, half again
as long! This is because the Z engine has 7 main bearings to the TR's 4.
Also the Z has an overhead cam, which is good and bad. From the standpoint
of ease of maintenance and repair, the TR wins easily. I hate dealing with
the timing chain on OHC engines when removing the cylinder head. Not that
you need to pull the head every weekend, but you know what I mean. The oil
pump on the Z can be replaced without dropping the sump, which could be
kind of nice.
One thing that is very interesting about the engines, is that although
presumably both cars had to meet the same emissions requirements, the
induction system on the TR is far more simple and logical. The Z has air
injection, a throttle opener solenoid, (which keeps the throttle open a
little on the overrun) an EGR valve, and easily three times as many hoses,
pipes, vacuum lines, etc. So, I guess either of two conditions existed
here... either the Z engine just was a gross polluter more so than the TR,
and to meet the federal requirements they had to load on all that other
junk, or Datsun was meeting federal requirements that were slated for 1976
or so. (I fear it was the latter) Whatever the case, TRs didn't get air
injection until 1976. On the Z, the SU copied Hitachi sidedrafts are far
more complicated and troublesome. One such instance is that the carbs
actually receive coolant from the engine block, and this makes the carbs
overheat and vapor-lock. The fix is to close off the appropriate pipes and
hoses and exclude the carbs from the cooling system. Why their system
worked in 1973 and not now, I'll never know. Or, maybe it never did work,
in which case why on earth did they design it that way!? There is no
"real" adjustment of mixture on the Z's Hitachis, both the needles and the
jets are fixed. There is a fine mixture adjustment on only the forward
carb, curiously enough. There is an attachment to the forward carb that
houses a large metering screw, and receives air from the air cleaner
assembly. The air passes through the metering screw and then splits that
flow of air into two pipes, one going directly to the forward carb, the
other going to the rear carb via a hose. At each carb, this air is
introduced into the venturi downstream from the needle & jet assembly. So,
rather than adding or subtracting fuel from the mixture like most of us are
familiar with, the Hitachis add or subtract air from the mixture.
Obviously, I'm partial to the set up on the Strombergs. Another strange
feature on the Z is the idle speed control, or "slow running screw". There
is a boss on the manifold balance tube into which a metering screw is
threaded, and from that orifice, there is a short hose which splits into
two hoses, each terminating again at the downstream side of each carb.
Turn the screw in, idle speed slows. Turn the screw out, idle speed goes
up. Not altogether sure how that one works... somebody help me out! The
TR6 engine compartment is a little more user friendly, except that the Z
has a clever little inspection light under the bonnet that can be moved
about the engine compartment. I'd have to say that the Z's oil filter is
more accessible though, too. In fact, the whole right side of the Z engine
is almost completely open... beautiful! But the left side, the carburettor
side, is a complete and total mess!
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