1st Series Aurelia FISPA air filter box.

[chriswgawne]

We have owned our 1st Series B20 for some 20 years and during all of this time I have been looking for a correct original FISPA air filter box in reasonable condition. It is round and sits on the 2 single choke Weber carbs which are on different centres to those fitted to 2nd Series B20's.
Bearing in mind the fact that there were only 500 1st Series B20s made, I was not optimistic but neither was I willing to cut, chop and adapt a 2.5l B20 air filter box to suit. Instead I used a couple of Vespa chrome go-faster conical air filters jammed in the carb throats which look a bit off but which do the job. It did however look like there was a big empty space between the carbs and the bonnet.

However a couple of weeks ago on ebay.it there was a B20 Air filter advertised which at a cursory glance looked like the standard one which fits 2.5l cars with the Weber 40DC carb. I did notice that the seller was also advertising a B20 engine and unusually he provided the engine number. Curiosity got the better of me and I realised that this was a 1st Series B20 engine so could the air filter also be from the same car?
To cut a long story short I bought the air filter and wonder of wonders, it is in god condition and correct.......but there is a fitting of some sort missing from the underside of the filter assembly which attaches the filter to the 2nd carb.
Can anyone throw any light on what this missing part looks like? It looks like it has a 4 bolt flange but I don't understand why Lancia didn't simply put 2 of the other carb fitting + clamp on the underside. Or am I missing a critical point here.
Any help or advice gratefully received.
Chris

[Sebastien]

Chris,
In my opinion Lancia provided for an adjustment to take into account that the distance between the throats of the 2 carbs is not fixed, but a result of mounting and casting tolerances of all the different bits (cylinder heads - intake manifolds - carbs) . So the missing flange should have some sort of slots for the mounting screws, to adjust the airfilter tightly on both carb throats, without inducing stresses.
Maybe an early parts book could shed light on this!

Would also be interesting to have the opinion of the owners of 2nd series B20, which have similar 2 carb airfilters (- > GG: are you there ?)

[GG]

Rising to the bait….

Not sure why the flange. Sebastien's point makes sense (and its the only reasonable explanation) but somehow it seems that this might be a place where drafting room logic was more cautious than necessary. The smarter move would have been to make both the overall throat mounting replaceable for a variety of different carb setups, but maybe it was just fine this way.

Here's a shot of the s.2. As you have pointed out, the intake manifolds for the s.2 are not the same, but don't know if the carb spacing is different as well. Probably by a little bit!   

The drawing is for a B20 air cleaner, but don't know whether s.1 or s.2.

[chriswgawne]

Thanks Geoffrey,
Thats a very useful photo + drawing.
I feel sure I will end up getting a flanged 4 hole collaqr fabricated. S12 carbs are much further apart than S1 and 'my' air filter is much deeper than the standard 2.5l  FISPA round box for single Weber 40dc type carb.
Chris

[GG]

It would seem then that the drawing is for a s.1 B20. The gap between the two carbs is much greater in the photo, and the proximity of the flanged bit to the perimeter much less as well than in the drawing.

Glad to help. Have a good lunch tomorrow!

[Sebastien]

GG

That drawing is very helpful, and everything is on it!

Could you report on what is written at the lower right of the drawing. It is incomplete in your scan:

La flangia deve poter subire una sposta.... in piu e in meno rispetto al proprio ....

Am sure this is the means of adjustment mentionned in my earlier post to the nominal dimension of 81 mm between carb throat centers!
Checking the real dimension between carb throats centers on an s.1 or s.2 B20 should show for which type the drawing applies!

[GG]

Centers on s.2 are 110mm apart, so drawing is likely s.1.

Interestingly, the tightening screws for the air filter housing (underneath) are positioned so that they can be tightened from one side, in fact, without having to move your body, even though you are working blind. Thoughtful.

There is no more in the photo of the drawing - I was intrigued by the drawing, and didn't realize the caption was important! Oh well…never enough…

[GG]

From Steve Katzman, comes the following information about an early s.4 Nardi air cleaner:
 
"It came off Pahl Morlangs 4S B20, that had supposedly been the Turin show car in it's time, prepped by Volpini. It had the Nardi set up, with Webers, and used the standard carb tops that start with a round orifice. Plenty of room under the hood of a coupe."

Note that it has adjustments similar to the earlier factory air cleaner.

Its unusual as its bent metal. Most of the Nardi air cleaners for the 2.5 liter we see here in the US were cast aluminum.

Also, it uses the Weber top covers with a single round orifice. Steve pointed out these covers are shown in the parts book for the GT2500. They are rarely seen. Perhaps the opening matches the Solex carbs used earlier. Would make sense if they did.