77 2F Hot air flap assembly question

[kurtnkegger]

My hot air intake flap assembly in the air cleaner isn't responding to the hot air as it should. I have taken it apart, and cleaned it up, and got it working better, but can't find any information on rebuild, or if parts are available.I've searched, but found nothing. This is the heat activated flap, and is not the vacuum type.Any advice on how to get this to operate better is appreciated.

 

[Degnol]

It may not be cold enough to open it. Have you tried putting it in the freezer?

 

[kurtnkegger]

I guess I should have been more specific...The flap acts as though it is always cold, and doesn't open fully (or close depending on how you look at it) for cold air intake. I can take it on extended drives, and it still stays about 1/2.

 

[subzali]

Hey Kurt, you might just have to find another one and compare the operation. I've never seen any kind of replacement parts or anything related to this item. Think about it though; if when it gets hot it opens up to allow cold air to come in, then the cold air will try to close it again, and it will work its way back and forth until it reaches an equilibrium position, i.e. halfway open. We haven't had a lot of hot days here in Denver yet so I bet that's what's happening. I bet when we see 90+ deg days you'll find the thing fully open.

 

[kurtnkegger]

The thing is, I'm sucking in air from a make-shift hot air tube from the exhaust manifold anyway, so the air coming in should be pretty friggin hot. I'm under the impression that the thermostat linkage that controls this gate activates at a pretty low temperature. You would think with all the SBC conversions going on, I could find an air cleaner with a working assembly. I've been looking, but haven't found any. I figured I would post here to get better insight on the temperature needed to activate the gate. If I dip the metal actuator in a cup of hot water it will move, but that would equate to REALLY hot air coming in.

I would suspect the heat rising from the manifold would help keep the gate open for proper cold air intake once the engine heats up.

Do you have one in your truck I could look at??

 

[ColonelMustardFJ40]

Maybe try using a heat gun to see if it works. I know my valve actuator does not move much but does open the valve (cold air intake) all of the way and mine is drawing air from a header tube.

 

[kurtnkegger]

I was under the impression the flap should actuate with less hot air than a hot air gun...

 

[subzali]

I'd have to look at the manual, but I think the actuation temperature is somewhere around 90 deg F. Unfortunately I removed mine in a moment of stupidity a couple years ago, and like you have been trying to find a new one and realized that finding a whole air cleaner would be easier. I waited and finally found an air cleaner locally, but I still have to go pick it up.

 

[kurtnkegger]

Thanks for the tempurature Matt, at least this gives me something more concrete to chase after. The vacuum actuated gates seem more plentiful than the heat activated type.

 

[subzali]

Just looked it up in the Emissions FSM - 81 deg F the flap is closed and drawing air from the exhaust manifold area. 90 deg F the flap is open and drawing air from the forward portion of the air intake. I guess between 81 and 90 deg F it is partly open, partly closed.