'72 with holley 1920

The flap does what is supposed to do (opens when cold and closes when hot) but it was the source of a nasty metal rattle. I've tried all kinds of grease and rubber pads and things to quiet it down but no luck. Yesterday I unplugged the vacume line that plugs into the diaphram and just plugged up the hose. Now the flap is always closed (no hot air let in) and no rattle either.

Any issue with running like this? It seems to idle a tad lower now but I'm not sure. Does it really help with warm ups that much?
Thanks WTS

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72 Scamp 225 /6, auto, radio delete, alum super six, cold air duct, pertronix ignitor II and flame thrower, 3.23 rear, 2.25" free flow exhaust

Not really. You have to remember that most of us running non-stock setups aren't using this. (OK, I'm still running a stock 1945 carb & air cleaner on my slant ).

This intake air preheater is there for emissions reasons: it helps the engine warm up a little faster; and, anything that helps get the engine to operating temperature faster helps reduce emissions. As I remember it, there were some studies done that found the fuel vaporized more completely at 100F and above. The air preheater helps the fuel/air mixture reach this temperature faster. Once the air inside the air cleaner assembly exceeds 100F this valve stays open.

If disconnecting this changed your idle rpm, it was leaking vacuum.

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My truck is a Frankenstein creation
Built from the dead carcasses of others
And brought BACK TO LIFE!

I bent the rod up some that goes into the door. Giving it a tighter fit helped mine out. Since you live in Bosten then yes, it helps to have it. I run mine in the winter because I don't have a heat flap in my exhaust manifold and need the extra heat to warm it up.

Thanks for the replies. The idle is definitely lower now, about 650 rpm, I kinda like it like that. Anyway, I don't understand this vacume thing and was hoping for some further explanation. I know that vacume advances the distributor as you open the throttle but beyond that not sure.

I put a screw into the hose and tiewrapped it up, is there a better way to seal the hose? Is it preferable to use a plug directly on the carb?
Thanks WTS

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72 Scamp 225 /6, auto, radio delete, alum super six, cold air duct, pertronix ignitor II and flame thrower, 3.23 rear, 2.25" free flow exhaust

Since you live in Mass, I would leave the hose there, and plug it. In damp, cold weather, you might have a problem with carb iceing. It will seem like the choke is stuck on. If this happens, just hook the hose back on.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225