1975 fj55 Air cleaner questions

[DTFJ45]

I am looking for a few answers. Please pardon my novice-ness I'm sure for most these question are bit dumb.
I am restoring a 1975 fj55. I am currently refurbishing the air cleaner.

I am not sure how the flap inside works?
I assume it might be a thermal flap?
How can I insure its working properly?
See photos:

Also I am looking for a lead on a feeder hose and inlet.
See photo:

 

[unklwedy]

Flap pulls in heated air off exhaust manifold. Old Crushers pulled in cold air all the time.

 

[LAMBCRUSHER]

If the vacuum doo dad doesn’t suck the flap open when the engine temp comes up wire it open all the time...

 

[wngrog]

Why would you want warm air mixed in? I’ve always thought if it’s not working and smog is off then it being shut is a non issue.

 

[J Mack]

Why would you want warm air mixed in? I’ve always thought if it’s not working and smog is off then it being shut is a non issue.

Look up the term venturi icing or carburetor icing. In a nut shell ice forms on the venturi some time after you start the engine and before everything warms up.

 

[LAMBCRUSHER]

I was under the impression you the flap is closed to cold fresh air at cold engine and then opens under vacuum when warm. If my understanding is correct, my rec is to block the flap open to cold fresh air all the time if the valve is in op...Toyota put it there to prevent cold weather icing...

 

[J Mack]

Carburetor icing can be a life and death problem if you teach your pig to fly and no you wouldn’t wire the flap open on your flying pig.

Fortunately we are specifically talking about non flying carbureted pigs so icing is more of an inconvenience than anything else and most just chalk it up the their vehicle being “cold blooded” so yes wire/bypass or replace with aftermarket air cleaner, ambient air temp is a better option than hot air if you’re going to lock it in one position.

Probably better info in this article,

https://www.hemmings.com/magazine/hcc/2015/03/Carburetor-Icing/3747511.html



Little chart showing conditions for icing, note the air temp is higher than you would think it would be for this phenomenon to occur.