What's that little thing

[Skunksmash]

What's that little thing that goes from the top of the passenger side header, to the bottom of the air cleaner/intake/filter housing? It's a tube of some kind, but what does it do? It's about a foot long, possibly a little longer. But not by much. I have it on my 87, im sure some of the rest of you have it on your stock engines, if you still have a stock engine. It's kinda puzzling because it's not like it actually attaches to the header in some way, it really just slides over a little bracket that clings to the header. So it's not sucking exhaust, or doing something for emissions or anything like that. It looks like all it could possibly be is something that sorta half uh, way transfers heat. But what what would be the purpose of that? Don't you make more power and economy if you can suck cold air instead?

[78 Chevyrado]

It sends warm/hot air to the air cleaner until the engine warms up.   The hot air makes the engine warm up faster which = power and economy.  Inside the air cleaner there's a door that opens or closes to allow either hot or cold air to enter selectively.  Once the engine warms up the door should block the hot air and only allow cool air to pass.

[Irish_Alley]

you make more power but less economy if you suck cold air. i thought that pipe was a heat riser but i think someone on here has told me other wise  but idk. but the perpose of it is to make the gas burn more efficiently when the engine is cold

[Skunksmash]

Well mine is so wore out it's coming in half so I thought about replacing it. I have no idea where to look for one though. All the local parts stores had was some flexible metal tubing stuff that didn't look quite right. I think you need that thin squishy metal tube type stuff.

[Irish_Alley]

go to the parts store and ask them for heat riser tubes they should point you the isle with battery cables and other things like that if i can remember right at least at autozone. and they way you described them thats how they look almost like dryer vent pipe

[VileZambonie]

It's called a stove pipe. It works with your thermostatic air cleaner. The heat riser is used in the exhaust to restrict exhaust flow and heat the intake manifold quickly during warm up.

[choptop]

Emissions garbage, and I disagree about cold air meaning less economy. Cold air=more oxygen which in turn means more air is getting into the cylinder which results in more efficient fuel burn. More power also means less throttle to do the same amount of work.

[Skunksmash]

Emissions garbage, and I disagree about cold air meaning less economy. Cold air=more oxygen which in turn means more air is getting into the cylinder which results in more efficient fuel burn. More power also means less throttle to do the same amount of work.

Yeah there has always been some debate about that. I never have got to the bottom of it, though.

[exilous]

Cold air intakes why else would they call them that if cold air wasnt better? I stand behind the cold air being more oxygenated for a better fuel burn.

[Irish_Alley]

on our trucks i don't think it really matters but when you get into the efi's and crap i think thats where it matters. since the ecm at first start up will give the engine more gas intill it warms up. the cold air intake tricks the ecm  into letting more gas into the cylinders cause it still thinking its a cold start. that will decrease you mpg but in turn give you more gas = more power to a limit or The efficiency is increased due to removing the restrictive stock airboxes and replacing them with smooth flowing, mandrel bent tubing. This increases the amount of air and the velocity of air flowing into the engine. The air going into the engine is also significantly cooler (and denser) on a cold air intake system because the air pulled into the intake is pulled from air that is further from the engine that has not been heated as much. The filters are also more efficient, allowing more air into the intake.

[Skunksmash]

If you look at those big plastic aftermarket K&N cold air intakes, they claim more HP and MPG. Course that is that one brand, maybe they do things a little differently.

[Irish_Alley]

If you look at those big plastic aftermarket K&N cold air intakes, they claim more HP and MPG. Course that is that one brand, maybe they do things a little differently.

even just their filters will offer that but more with the CAI

[BOCEPHUS]

I like choptops thinking its garbage on these old cars and trucks. I removed mine a long time ago.
But on these new cars you want just remove it . I think it does help on them. On these new cars they need to be replaced I have replaced many on them , It can cause a lot of things to go wrong if they are not replaced . I have seen that stuff get in the gas tank and what a mess.

[VileZambonie]

Cold air makes fuel atomization very difficult especially in cold weather and during a cold start up. That is the purpose of the heat riser and thermostatic air cleaner with stove pipe. A cooler air charge is better in a warmed up engine for making power not for lowering emissions and better economy. If all of the fuel cannot be burned in combustion it's wasted. If you have more oxygen you need more fuel to have the correct a/f ratio. Anyone who is concerned with mileage should upgrade to at least a TBI system. A carburetor is designed to give a homogenous mixture of air and fuel to the engine under a few different modes of operation. Without a feedback system there is no way to regulate the changes in air density or mass.

[Skunksmash]

Well I went to the parts store and got a replacement. Not really exactly the same as the old one, this one is a lot harder and thicker. It's more like some kind of rolled metal tubing. But I imagine that it will work just fine, given what yall said that it is meant to do.

However, this thread does lead me to another question. Someone mentioned something about cold starts and that got me thinking about how poorly my truck runs when it's cold. I can't imagine that it would run that bad when it was new (when cold) so what makes an old TBI motor run so bad when cold? It takes it about 2 miles to warm up. Once it warms up it's just fine. Even for the rest of the day it's fine, cause i guess there is some residual heat left. But dang it runs like poop when it's cold. What gets old, that could possibly be replaced, that could make it run more like it did when it was new, when cold? Probly a newly rebuilt motor huh lol.