Following the myth of the non-existing JZs, there is another myth reciprocation throughout the Junior Zagato world...

The JZ is known to be a, technically, simple car... the platform and mechanicals come from the Spider 1300 Junior and are therewith interchangeable with virtually all other 105 Series Alfa's. Whether you want to put the larger 2000-series brakes on it, a different axle ratio or simply a larger engine, it is all (almost) plug & play. A great thing as some of the items can truly be seen as "bolt-on goodies" or even "go-fast goodies" and, as a wise man once said... what can be bolted on, can be bolted off... so there is no need for "destructive modification" to put these goodies on your JZ and wear parts are in plentiful supply.

So, as far as the mechanicals are concerned, a JZ is an easy to maintain, easy to upgrade car. It gets tricky there where the JZ uses "JZ-specific" parts... small items like trim, interior parts etc have long been sold out at the factory and finding NOS parts (New-Old-Stock) at dealerships... well... there's a better change of spotting a herd of pink elephants grazing on the top of the Empire State Building so to speak...

Luckily, a number of parts dealers have been re-manufacturing some of the parts which are most in demand so when the stainless steel grill surrounds are missing or are warped, you can simply order them and they come pretty close to the original spec. Same goes for the ever-so fragile Plexiglas shields. Also the stainless steel bumper tops are being remanufactured and probably many more parts.

For the rest, the JZ owner has little choice but to wait until that one illustrious part that he has been looking for is being offered for sale. The number of JZ's that is being stripped for parts is minimal as, with the values on the up, most cars stand a good chance of being restored or at least being kept by their owners.

Having owned a JZ that was in need of some JZ-specific parts, I know first hand that it requires a lot of patience and deep pockets to complete a car. Having always been on the look-out for the parts I needed, I became completely opportunistic in my buying habits as if I didn't need the part that came up for sale NOW... I might need it in the future... and who says that it will be available when I indeed need it? This has led to a stockpile of JZ parts (no... I'm NOT selling!) kept in safe storage for when the day comes that I need them...

Alfa Romeo used to use a very simple part numbering system... if a part was generic, it would get an almost random number but when a part was model specific, the part number starts with the first 5 digits of the model code, followed by a sequence of digits that make up the actual part number.

So, with the JZ 1300 being model code 105.93, all part numbers starting with 105.93 were specifically made for the JZ 1300, or at least the JZ 1300 was the first model to use that part.

Going through the parts catalog for the JZ, which only lists the JZ-specific parts, I came to an impressive list of 18 models from which the JZ is "borrowing" parts. This list can be found on the "Alfa Romeo Parts Bin" page.

From the above, we know that any part starting 105.93 is JZ-specific hence scarce... and scarce definitely translates into "expensive!" in this case... So, it's not unexpected that JZ owners have been looking for alternative sources for parts. Door handles from a 1970 2000 Berlina fit without to much modification etc.

Now we come to the "Monti in the JZ "myth....

From the parts bin, we can see that the JZ indeed borrows from the Montreal parts pool... even though the Montreal officially went into production later than the JZ... those parts were simply designed for the Montreal and then also used for the JZ.

We also know that although the basic floor pan of the Spider 1300 was used, it was modified in the rear end to fit the shorter JZ body. That whole process is explained HERE.

With the boot floor having been shortened, the standard Spider fuel tank was too big to fit and a special tank was required. Alfa / Zagato used a design that would fit the short boot floor yet allowed a decent capacity of 50 liters and ended up with the fuel filler on the right side of the car... whereas all other 105 Series Alfa's had the fuel filler on the left side...

All 105 Series cars? Well... almost. All but one... The glorious Montreal! Just as big a commercial failure as the JZ but just as iconic 40 years down the road...

Rumor has it that the JZ uses the exact same fuel tank as the Montreal... where the rumor comes from, I don't know... but it has been around for more than 15 years...

But... but... but...

When I look in the owner manual of the JZ... it clearly lists a fuel capacity of 50 liters... and the Montreal manual lists 63 liters... too much of a difference to be a commercial white lie...

Add to that that the JZ tank carries part number 105.93.32.010.00... a 105.93 number... hence designed for the JZ... and the Montreal tank is 105.64.32.010.01.. a 105.64 number... hence designed for the Montreal...

But then where does the rumor that the cars use the same tank come from?

For that we will have to take a loser look at them...

The JZ fuel tank assembly:

And the Montreal fuel tank assembly:

They look quite similar at first glance, don't they?

As a matter of fact, they do... even more than "quite similar"... remarkably similar... but not completely...

OK, the drawings are from a different perspective and I don't have the software to 3D turn one of the drawings 90 degrees but it doesn't take too much imagination to see the similarities...

Wait... I'll enlarge the drawings a bit and remove as much of the other parts as possible...

It should be easy to come up with a theory behind the rumor...

Looking at both drawings, it is clear to see that both tanks share the same curvature to go "around" the spare wheel well to optimize the use of available space...

But that is just about where the similarities end...

The filler neck is distinctly different... the Montreal neck being straight and the JZ neck angled...

The bottom halves of both tanks are also distinctly different... the one of the Montreal being considerably deeper than that of the JZ.

So... the most probable thing that happened is as follows: When it turned out that the boot floor of the Spider had to be shortened to such an extend that the standard fuel tank wouldn't fit anymore, the engineers started to look as what options they had in-house and the only significantly different fuel tank that Alfa had designed at that time was the Montreal tank.

The Montreal tank did fit the "floor plan" of the JZ trunk but the bottom half but was too deep and the filler neck too straight plus that the filler neck would end up on the right hand side of the car, like with the Montreal... Additionally, the Montreal has a filter element for the Spica injection system screwed into the bottom, as visible in the top drawing, something that the JZ didn't need with its carbureted Nord engine.

To keep things as easy as possible, the JZ tank was made of a Montreal top half with the correct dimensions and "floor plan", combined with a shallower bottom half and an angled filler neck, thus ending up with a capacity of "only" 50 liters compared to the Montreal's 63 liters.

Theoretically, a Montreal tank would probably fit a JZ, provided the filler neck is modified, and would give a bigger fuel capacity but chances are that it ends up hanging too far below the JZ floor pan to cope with traffic.

Therewith there is a definite answer to the question whether the JZ uses a Montreal fuel tank or not:

No.

BUT... the design is loosely based on that of the Montreal tank.

And YES... that is the reason that the JZ has the fuel filler on the right hand side of the car.

Will we ever know for sure that this is exactly how it went? No... but it is a plausable theory; fact remains that the tanks are different.

Please bear in mind that this ONLY applies to the JZ 1300 as the JZ 1600 used the standard Spider 1600 floor pan, including the standard boot floor and fuel tank!

Jack Habits
August 2012

Thanks to Peter Olasz from Budapest for providing the drawing of the Montreal tank and information from the Montreal Owner's Manual.