red hot headers (glowing)

dadiesel5 · Apr 14, 2007

i recently rebuilt my 5.0 and put forged pistons trick flow topend and a 65mm throttle body and now when i started the car and run it at a fast idle at 2 to 2500rpm after about 3 or 4 min the headers get red hot, i have the stock maf as of now and stock injectors and stock fuel pump what do you guys think is going on here.

DemonGT · Apr 14, 2007

check fuel pressure

Daggar · Apr 14, 2007

You're sucking unmetered air in from someplace (Vac Leak).

--also--

What sized injectors are you using?
What MAF are you using?
What computer are you running?

dadiesel5 · Apr 14, 2007

19lb injectors stock maf whats the best way to check for a vac leak.

Daggar · Apr 14, 2007

A leak like the one you describe should be pretty easy to find. Look around. If that doesn't work, get yourself a can of engine start and spray it SPARINGLY around the vac lines in your engine bay. When the motor idles up, then you'll know you're getting close to the areas where the leak is.

86bluecobra · Apr 14, 2007

Am i wrong to also suggest this could be an issue with retarded timing. That can cause headers to heat right up. Probably a lean issue but it could be timing aswell.

Woodrow · Apr 14, 2007

Headers glow because of unburnt gas getting in them and igniting, not because it is lean. If anything its way to rich.

Daggar · Apr 14, 2007

Woodrow said:
Headers glow because of unburnt gas getting in them and igniting, not because it is lean. If anything its way to rich.

Actually, that's backwards. Pull the large PCV line off of your throttle body and let your car idle in the driveway for a while after the sun goes down. Let us know what happen.

86bluecobra · Apr 14, 2007

A rich condition in the exhaust makes your eyes water. I know and so does anyone who drives behind me. lol. I have to get my carb jetted properly.

795.0pacecar · Apr 14, 2007

Daggar said:
Actually, that's backwards. Pull the large PCV line off of your throttle body and let your car idle in the driveway for a while after the sun goes down. Let us know what happen.

No, he is right, a rich condition or a timing problem will cause headers to glow. Unburnt fuel burns in them, explain how that would happen with a lean condition.

86bluecobra · Apr 14, 2007

795.0pacecar said:
No, he is right, a rich condition or a timing problem will cause headers to glow. Unburnt fuel burns in them, explain how that would happen with a lean condition.

I won't believe that a rich condition on its own will cause the headers to glow. As I stated my car runs rich and I don't have that issue. If however my timing was off (ie way retarded and rich) then yes both together would cause the issue. Whats Daggs is saying though makes sense because a lean condition raises the temp in the cylinders. Thus raising the exhaust temp thus causing a header to glow. Also could burn the exhaust valve or burn a hole in the piston.

Mr. Rustypwnz · Apr 14, 2007

I ran the svo with 25psi and no fuel press, knockin like crazy and it was idling very high, and it caused it to glow the cast iron header, I also blew a hose clamp for the ic off(vac leak). listen to this, when the car is cold, the o2 sensors tell the computer to richen the mix right? so why dosent the headers get hot on cold startup, my 7up car dosent, the notch dosent and the 86gt with lt's dont get hot for a while, like 60 seconds, it will only glow the headers when the timing is way off and the fp is really low or as daggs said a vac leak. I believe more oxygen to gas burns hotter than high gas levels to low oxy.

cj99 · Apr 14, 2007

running lean makes your exhasut gas hotter. running rich makes it cooler. thats how you O2 sensor knows if you running rich or lean. the wird thing is the o2 should be dumpping more fuel because of this. so first of all run the codes in you computer to see what it says. then check fuel pressure. also if you were way rich then when you pull a spark plug to see if it is wet or white. white would say hot. wet would be rich. you running way off some where. also how does the car drive or rev. does it rev slow. if so the timing is to retarded. if its hard to start you most liky to advaned. just my 2 cents, but you better fix it fast before you burn a hole in a piston !

795.0pacecar · Apr 14, 2007

We are talking very rich, and or a timing issue that will cause glowing headers. A lean condition does make for hotter combustion chamber temps but not necessarily hotter exhaust temps. I am about to have a degree in this stuff, I know what I'm talking about. There is a lot of misinformation floating around here from some so called experts.

If you guys don't believe me then look it up. I did some of the work for you.
http://racingarticles.com/article_racing-56.html
7th down.

Woodrow · Apr 14, 2007

Here is what he said on another site...

o2 sensors have about 200 miles or so....plugs smell like gas and don't look white..but the car has only run about two minutes total since I started with this problem.

I ran it with open headers so I know it's not the convertors.

I put a vacuum guage on it and the vacuum seems a little low (about 15') but it holds steady.

The headers are hot the instant the car starts.

Anymore word of wisdom Daggs & cobra?

86bluecobra · Apr 14, 2007

Woodrow said:
Here is what he said on another site...

Anymore word of wisdom Daggs & cobra?

well.............I still think that extra fuel or a running rich will not cause the issue the guy is talking about. It has to be an issue with timing more then anything. If your timing was set properly and you were rich there shouldn't be an issue. I run 10 to 1 AFR. I have a wide band o2 sensor. Thats rich. And no glowing headers. I do have 18 degrees intial timing anf 38 degrees total. If however i was to retard that then i would have glowing headers. It has to be a combination not just running rich.

795.0pacecar · Apr 14, 2007

It would depend on how rich its running, but it is most likely a timing issue or a combo of the two.

Daggar · Apr 14, 2007

Woodrow said:
Here is what he said on another site...

Anymore word of wisdom Daggs & cobra?

I also run an Innovate LM-1 wideband. I've seen the effects of running both lean and rich. The test that I proposed above will clear it all up for you in a heart-beat. Allow a decent amount of unmetered air into combo (causing it to go lean) and watch your headers glow (been there, done that, got the t-shirt).

I've also run extremely rich during tuning (as much as 9:1 AFR). Under extremely rich conditions, you'll see/hear popping/backfiring LONG before you'll ever get unspent combustion to burn in the headers.

Your quote above has little or no relavance to the topic at hand. Consider for a moment, how a 4 cycle engine operates. Between each combustion cycle, there is a "clearing" cycle. Any unspent combustable material you might have in the compression stroke would be quickly evacuated through the exhaust. If not... if it's still burning when the exhaust valve opens, it will tell on you (flash-bang).

cj99 · Apr 14, 2007

who knows

ok, it sounds like there is a diff of opion.
but i think most people here would agree with this .
1) lets get a timing light on it and set it to stock timing for now . 10 deg
2) CHECK THE CODES there probly all kinds being this is a modded car but could not hurt to look at them
3) check fuel pressure
then get back to use with this info
i am also running way rich ( no o2's ) and i do not have glowing headers but i have my timing around 15-16 deg ( base timing)
lets use know

Daggar · Apr 14, 2007

795.0pacecar said:
No, he is right, a rich condition or a timing problem will cause headers to glow. Unburnt fuel burns in them, explain how that would happen with a lean condition.

A lean condition will make for very HOT combustion. If you'd ever tuned by EGT (carb or FI, doesn't matter), than your question would be academic.

One other thing to consider... if you get your AFR too lean, what happens? You get detonation. Why? Because the combustion chamber and mixture is so hot that the mixture explodes vs. burning along a front.

Once again, perform the test that I've indicated above. Let me know how it works out for ya.

red hot headers (glowing)

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