Hot Air Duct

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Julian

Hot Air Duct

Unread post by Julian »

I have recently purchased a new hot air duct (2” round hose) for use with the air filter on my 72 S2 Coupe as this has always been missing from the car. I can clearly see where the duct fits to the underside of the air filter box, however I have no idea what route the pipe takes to the exhaust and how it is fitted. There does not appear to be any fixings or brackets around this area for the other end of the duct?

Any advice would be appreciated

Thanks Julian
Paul de Raymond Leclercq

Re: Hot Air Duct

Unread post by Paul de Raymond Leclercq »

Dear Julian,

The hose is routed over the top of the bell-housing, thereby obstructing your view of the timing marks on the flywheel. It then passes round the back of the block and is fitted to a flared trumpet that is mounted on the end two exhaust manifold bolts.

This equipment is entirely useless unless you live in a climate that has very severe winters; because it is always in the way I have always thrown them away and I have driven in sub-zero temperatures without problems.

Paul
Julian

Re: Hot Air Duct

Unread post by Julian »

Paul,

Thanks for the quick response, I will fabricate up a trumpet for the other end of the pipe.

I must confess that when I bought the duct I thought that it was probably as useful as a lead balloon (even though the weather can get fairly arctic up here in Manchester). However as I'm completing a full nut and bolt rebuild I thought it would be nice to have it in place. It's a good example of the Italian practice of engineering a solution for a problem that does not really exist!

Once again, Many Thanks

Julian
Paul de Raymond Leclercq

Re: Hot Air Duct

Unread post by Paul de Raymond Leclercq »

Julian,

It should not be difficult to find the trumpet; I regret to say that I have thron away quite a few and as I say it makes timing the ignition and the camshafts a pain.

Paul
Huib Geurink

Re: Hot Air Duct

Unread post by Huib Geurink »

The reason for the designer to put it there is probably ice on the carburators. The 1C berlina with its single carb had a serious problem with ice. Easily solved by the way by bending the mounting plate of the carb a bit.

The later Fulvia's with the two double choke carbs hardly had an ice problem. As Paul says the hose is always in the way. I threw them away many years ago like almost everbody else.

Last year I re-installed one to test if it helped in shortening the time to warm up the engine in winter. I figured that if I put already warm air into the engine the water might heat up quicker. The reason for the test was that I hate cold cars. Perhaps the result of my indonesian descend. Anyway, it made no difference at all.

It is not severely cold weather that causes icing. To make ice one needs water in addition to subzero temperatures. At very low temperatures there is not enough moisture in the air. The weather we have now in Holland is ideal for carburetor ice. Foggy and temperatures around zero. One can suffer from carburetor ice also at temperatures above zero. The vaporising of the petrol takes heath. It sometimes reduces the temperature by 20 degrees C.
Randy Adams

Re: Hot Air Duct

Unread post by Randy Adams »

Gee, I would have thought that the purpose of the duct was to help speed the heating of the air/fuel mixture and the intake ports on a cold car so that it would not need the choke for as long. In Los Angeles this was never an issue. The only time I ever had one of those on one of my cars was when a California smog equipment inspector insisted that I re-install it. It's interesting that the duct doesn't even accomplish anything in the colder climates.
Paul de Raymond Leclercq

Re: Hot Air Duct

Unread post by Paul de Raymond Leclercq »

Happy New Year.

My own view is that in our relatively temperate climate (in England) is that the "contraption" has never proved necessary even in the coldest weather - I know this because of course I have always thrown the thing away!

It may be that in very cold weather say in Canada or Sweden, it may be of some benefit as it is engaged by selecting the winter setting on the air intake and may prevent carburettor icing.

I never use the choke on a Fulvia if it can possibly be avoided; I have always found that provided all is as it should be, then three pumps of the accelerator pedal plus of course de-clutching, is all that is necessary to start a Fulvia.

Paul
Huib Geurink

Re: Hot Air Duct

Unread post by Huib Geurink »

Happy new year!

Right Paul. A Fulvia that is in order should start without choke on first spark after three pumps, any weather.
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