72' Type 4 Oil Bath Air Cleaner, Warm air Air Intake Hoses Options

[Ishley]

After 2 years of work....I've completed my '72 restoration...but one thing has me stymied.

I have an oil bath air filter... (pictured) and it has 2 air input points... one is a plastic goose neck and the other is a hose connection controlled by a vacuum system. The mysterious hose I think is supposed to run over to a connection point added to the engine tin...into a "hot air riser". I have no such connection point. I thought my motor was the original 1.7.... which I've now rebuilt into a 2056. I do not have a hot air riser tube.

The only place I've ever spotted a 72 with this type of a air cleaner is on a YouTube video of an original 72. https://youtu.be/w-c6Deg3fBU?si=FPjt3Fhg0lqMsaad Spotted at around 11:20 of this video. The video doesn't show where this hose terminates... but I assume into the mysterious "Hot Air Riser".

I also see in the PET diagrams they show this tube which would bolt to the engine tin behind the cylinder one location. I see a few ebay listings for this tube... but I've never seen it on any of the engines I've looked at.

Does anyone have insight into a hot air riser system.... that bolts to the engine tin behind cylinder one? I don't really think I need it... as this is really a summer only car... but I hate having this unknown empty input point on my air cleaner staring me in the face every time I pop the engine lid.