Glowing Hooker Headers!

[70Charger493C.I.]

Was tunning in the 493 stroker. 36 total timming. was running about 2800 rpms for 8 mins. headers started to glow? is that because the carb is set to lean etc? just wondering. I know its not right. Any insight would help. Thanks.
And the temp was about 205. Thats too hot for me. 185 190 tops.

 

[74sundance]

Yeah it's running lean.Fatten up the mix and it should cool down but you might also have to play with the timming.

 

[Cranky]

205 really isn't hot but were you driving it for 8 mins at 2800 or stationary....?

 

[Southernman]

While you didn't specify a carb, for an engine that size, I'd assume you're running a big holley. I'm running a Dominator, so here's some things I can share that will apply to most Holleys.

If your headers are glowing red, it's because combustion is taking place inside of the exhaust pipe itself, which means your idle circuit is too rich.

While most rodders tend to immediately think it's from a lean condition; it's not. For anyone whose ever dealt with "blue-ing" of the chrome pipes on their motorcycle, that condition is usually caused by idling with the choke engaged too long, which restricts air (richens the idle circuit), and causes combustion to take place inside the exhaust pipe - resulting in "blued" chrome. Think about it:

In order for the pipe to glow cherry red, the combustion process must be occuring downstream of the chamber (in the pipe itself), where excess fuel is self-igniting (more fuel = more heat). Typically, a slightly lean condition won't hurt you at idle, and it will definitely not turn your exhaust pipes red, but it can be disastrous under load...

Your car is too rich, and here's a few things you need to check:

Lean out the idle-air circuit a few sized and check the pipes again. 2-4 sizes will typically resolve the "glowing pipes" issue (go to the next size larger air bleeds or idle circuit - for 4150 series).

Then optimize the idle circuit. Remember, the "sweet spot" for idle screws is somewhere around 1-1 3/4 turns out. If you're less than that, the idle circuit too rich; more than that, it's too lean. Conversely, you will increase or decrease your idle-air bleeds/idle circuitry until you are somewhere within the 1 - 1 3/4 turns out on the adjuster screws, which will allow for maximum tuneability.

The other thing you may want to invest in is a good wide band Air/Fuel gauge, which will permit you to tune the car as you drive it or race it. It will also keep you from destroying an engine under load due to the power circuit being too lean or from cylinder wash down.

I hope this helps.

Southernman

 

[Satellite65]

While you didn't specify a carb, for an engine that size, I'd assume you're running a big holley. I'm running a Dominator, so here's some things I can share that will apply to most Holleys.

If your headers are glowing red, it's because combustion is taking place inside of the exhaust pipe itself, which means your idle circuit is too rich.

While most rodders tend to immediately think it's from a lean condition; it's not. For anyone whose ever dealt with "blue-ing" of the chrome pipes on their motorcycle, that condition is usually caused by idling with the choke engaged too long, which restricts air (richens the idle circuit), and causes combustion to take place inside the exhaust pipe - resulting in "blued" chrome. Think about it:

In order for the pipe to glow cherry red, the combustion process must be occuring downstream of the chamber (in the pipe itself), where excess fuel is self-igniting (more fuel = more heat). Typically, a slightly lean condition won't hurt you at idle, and it will definitely not turn your exhaust pipes red, but it can be disastrous under load...

Your car is too rich, and here's a few things you need to check:

Lean out the idle-air circuit a few sized and check the pipes again. 2-4 sizes will typically resolve the "glowing pipes" issue (go to the next size larger air bleeds or idle circuit - for 4150 series).

Then optimize the idle circuit. Remember, the "sweet spot" for idle screws is somewhere around 1-1 3/4 turns out. If you're less than that, the idle circuit too rich; more than that, it's too lean. Conversely, you will increase or decrease your idle-air bleeds/idle circuitry until you are somewhere within the 1 - 1 3/4 turns out on the adjuster screws, which will allow for maximum tuneability.

The other thing you may want to invest in is a good wide band Air/Fuel gauge, which will permit you to tune the car as you drive it or race it. It will also keep you from destroying an engine under load due to the power circuit being too lean or from cylinder wash down.

I hope this helps.

Southernman

I agree, and late timing may cause the same problem. The fuel is being ignited later in the cycle, and still burning as it's being pushed out the exhaust.

 

[74sundance]

Yeah it's running lean.Fatten up the mix and it should cool down but you might also have to play with the timming.

Hmmmm,should I retract my previous statement lol
I did read some where that loose headders bolts can cause the headders to glow as well, anyone want to add to that?

 

[ilm65]

Glowing headers

Southernman has some valid points. Timing has an affect if the mixture is allowed to ignite and then burn once the exhaust valve is open. However, keep in mind, oxygen burns hotter than fuel. Too little fuel, and your charge is burning too hot. If your timing is in order, get some more fuel in that engine--your headers will cool right down. And no, 205 isn't really hot. The newer engines are designed to run at 205-210 in brand new cars. Wife's Cadillac CTS runs around 210 all the time. My 440 + .030 with aluminum heads runs 190 to 205 with no problems. You're not in trouble until you get in sustained temps of 210-215.

 

[Southernman]

Guys, not trying to be argumentative, as I truly enjoy these kind of discussions.

However, with all due respect, keep in mind that oxygen does not burn unless mixed with fuel, or a catalyst. You cannot use a flint starter on your oxygen tank to 'ignite' the oxygen tank contents. Similarly, if you light the acetolene first, you can extinguish the flame (fuel) with the addition of too much oxygen - and the temperature at the tip will drop once you cross the optimal mixture threshold from rich to 'lean'.

If you take the above statement [oxygen burns hotter than fuel] at face value, then turning up the oxygen, would result in more BTU's/lb regardless of how far you turned the knob and we all know that's simply not true.

Fuels require the addition of oxygen, and a spark, in order to ignite. Since oxygen doesn't burn, you can rest assured, too little fuel means there is LESS heat - not more... It's simple physics. If oxygen truly 'burned', none of us would probably be around today to help define the revised meaning of 'scroched earth'...

Think of it this way:

If you use charcoal starter fluid to cook on the weekends, like I do, then you're familiar with what happens when you spray starter fluid (Increase the level of fuel to the source) on the already hot briquettes. You get a violent flare up (explosion) resulting from the ADDITION of fuel, and it does not do anything to 'cool things down'. Add more fuel = more heat. You have richened your barbecues idle circuit and, once the extra fuel burns off, the temperature drops.

Adding fuel will make the condition worse.

This discussion is relevant on the lower rpm scale, such as idle and off-idle transition. It's an entirely different discussion when you discuss high rpm, high load, conditions where a lean condition must be avoided to prevent self destruction from detonation...

I agree with the operating temperature comments. Sustained temps over 210 and you should work on a resolution.

Also, before we get too carried away with this discussion, what kind of carb are you running ? 4500 or 4150 ?

Southernman

 

[74sundance]

Guys, not trying to be argumentative, as I truly enjoy these kind of discussions.

However, with all due respect, keep in mind that oxygen does not burn unless mixed with fuel, or a catalyst. You cannot use a flint starter on your oxygen tank to 'ignite' the oxygen tank contents. Similarly, if you light the acetolene first, you can extinguish the flame (fuel) with the addition of too much oxygen - and the temperature at the tip will drop once you cross the optimal mixture threshold from rich to 'lean'.

If you take the above statement [oxygen burns hotter than fuel] at face value, then turning up the oxygen, would result in more BTU's/lb regardless of how far you turned the knob and we all know that's simply not true.

Fuels require the addition of oxygen, and a spark, in order to ignite. Since oxygen doesn't burn, you can rest assured, too little fuel means there is LESS heat - not more... It's simple physics. If oxygen truly 'burned', none of us would probably be around today to help define the revised meaning of 'scroched earth'...

Think of it this way:

If you use charcoal starter fluid to cook on the weekends, like I do, then you're familiar with what happens when you spray starter fluid (Increase the level of fuel to the source) on the already hot briquettes. You get a violent flare up (explosion) resulting from the ADDITION of fuel, and it does not do anything to 'cool things down'. Add more fuel = more heat. You have richened your barbecues idle circuit and, once the extra fuel burns off, the temperature drops.

Adding fuel will make the condition worse.

This discussion is relevant on the lower rpm scale, such as idle and off-idle transition. It's an entirely different discussion when you discuss high rpm, high load, conditions where a lean condition must be avoided to prevent self destruction from detonation...

I agree with the operating temperature comments. Sustained temps over 210 and you should work on a resolution.

Also, before we get too carried away with this discussion, what kind of carb are you running ? 4500 or 4150 ?

Southernman

I'm not totally convinced,My 1968 318 with 600cfm Holley made my headers glow in my old Satellite and I was taught when I was apprenticing as well as in engine building school in college that you need to richen up the mix to cool the motor. I did just that and the problem went away. I just built a 21hp John Deere motor and had problems with the exhaust glowing red hot...John Deere tech told me to richen up the mix by 1/4 turn to fix the lean condition.The motor runs perfect now and the exhaust does not glow at all.I also had a motor blow #1 cylinder in a 4g63 Eagle Talon from running lean while boosting it actually melted the top of the FORGED piston.I know for a fact it was lean on that cylinder due to a faulty injector.
I'm not saying any one here is wrong,All I can say is try and richen up the mix and see what happens, it's by far the easiest thing to do and then report back to us.
Plus if it was too rich leaving unburned fuel in the exhaust and running hot it should be popping threw the exhaust.

 

[detmatt1]

Good info here!

 

[Southernman]

There is another scenario...

I had a guy bring me his car ( a v-8 Vega ) years ago complaining that the headers wouldn't stop glowing red.

I tuned his carb and got it running great, however the headers still wanted to glow cherry red, especially under cruise and full power.

Turns out his headers were thin-wall and, no matter how we tuned it, there just wasn't enough material in the pipes themselves to alleviate the problem. He replaced the headers with a good set of Hookers and the problem went away... Go figure.

Southernman

 

[Meep-Meep]

As stated by Southernman, a rich mixture will make for hotter exhaust gas temperatures as opposed to a lean mixture. Years ago I drilled .040" holes in my primaries as close as possible to the port in order to insert a thermocouple wire into the exhaust gas stream. There was a rapid temp change as I adjusted the idle mixture. Open the screws and the temp went up.

And as for the glowing headers that might not be a 100% accurate method to determine if the mixture is too lean or rich. The following could explain why a thick wall tube will react differently than a thin wall tube or even an iron manifold. The thin tube has less ability to conduct heat, and since heat transfer is a function of surface area, the heat tends to build up at the source if it can't conduct away fast enough, hence red header tubes. Being that the flow of heat energy is always from hot to cold I'm wondering if the factory had the same idea by not using an exhaust manifold gasket when the cars were new.

Some good info on fire -

"The fire stops because a lower concentration of fuel vapor in the flame leads to a decrease in energy release and a lower temperature. Removing the fuel thereby decreases the heat."

http://en.wikipedia.org/wiki/Fire_triangle



Increasing oxygen content really lowers the amount of energy required to start the fire therefore it may give the impression that it's burning hotter. As an example it's difficult to light diesel fuel on fire with a match but by adding oxygen you can probably set it off from the friction of rubbing two sticks together. This is probably why a lean engine will ping or detonate. The heat of compression alone can set it off.

 

[Kimber67]

I am sure not an expert by any stretch of the imagination but watching my hubby and his pals tune engines and break in flat tappet cams etc for years now, I have seen a lot of glowing headers. I asked him about this thread and was told that tuning is better done by plug readings and you only had to worry about lean if THEY (the spark plugs) started glowing!

 

[70Charger493C.I.]

I am running a 4150 style carb. Quick Fuel Q-950 And thanks for the information. It really helps. and the wide band is a great idea. Had a friend also telling me to get one of those. Then i can let out of it if i see a issue etc. Thanks for your knowledge. Ill try the adjustments on the carb and let ya know how they work out.

 

[6packMIKE]

good discussion guys.

 

[rapidtransitric]

i had a situation once of glowing red headers. turned out to be a blown power valve. which in turn caused the dumping of raw fuel through the headers