why do headers glow???

[SYDEWAYZ71]

Well first off the motor is a n/a ZZ430, air gap, holley 750 nothing special. I just changed my intake gasket (was leaking) and just installed the brand new headers which HEDMAN was so kind to warranty for me due to a crack in the pipe. But yesterday I drove the car for the first time in 6 months and while I was on the freeway my friend who was driving next to me called me and said my headers were glowing?? uuummmm??? well timing is set @34* @3,700rpm not sure what else you would need to know to better help me. Could this be a possible lean condition or timing issue? Other than that the car runs fine no sign of anything being out of whak.

[383blown]

You should definitly retard your timing a couple degrees maybe even three or four depending on the quality of fuel your getting!

[CoryM]

Glowing headers is too lean or too retarded (fuel is still burning when the exhaust valve opens). Easiest way to figure out which is to pull a spark plug after driving it w/o letting it idle for long. Ive been known to pull over and shut off on the side of the road and pull a (hot) spark plug out. If its white you are running too lean. If its a nice tan/light brown colour you should look into your timing. Post a pic of the plug if you are unsure. Also possible you have a vacuum leak leaning out the engine..... was the intake leaking coolant,oil or air?
34 degrees total sounds about right for that engine to me. What does the rest of the timing curve look like (base, vacuum, 1500rpm, 2500rpm etc)?
EDIT: also what temp does the car run at?

[gmachinz]

Thickness (or thin-ness, rather) of steel can play a part in it as well. Are these headers coated? I'd say it's a lean issue. -Jabin

[ProdigyCustoms]

She's Lean!

[SYDEWAYZ71]

So last night I checked timing and its 10*@idle, 30*@3,000, 36*4,000. Then I took it out and made a quick pass and pulled a plug and it was pretty much white so I changed the plugs and tried again...same thing. The carb is a 4160 and I put secondary blocks on it so I could try out different jets instead of the plates. I know the primaries are 72's and sec. are 75's. I am still getting a bit of detonation when I'm driving in 2nd gear under my stall speed (hughes 2500) and I give it hard throttle. I only run Chevron or 76 gas 91 octane and yes the headers are coated. Oh the temp stays around 180-195*.

[zbugger]

Definitely lean. Be careful because you can burn a piston or a valve that way. Drop the timing to 34 max. I think that should be decent. Richen it up a bit too. Definitely needs it.

[gmachinz]

Wow...I'd say you have considerably small jets in it right now. Try a 78 primary and an 84 secondary. You may want to swap to a more aggressive pump cam too-I'd go with the orange one (steeper ramp, more gradual fuel delivery) and if it exhibits any bog off the line, change to a 50cc pump kit and go with a little larger squirt nozzles. Stick with the stock secondary spring if you have a 2800+ converter (or if running a stick) and if you are running anything steeper than 3.73's out back. -Jabin

[ProdigyCustoms]

I mostly agree with the other ideas. I would bump the jet one size. If it does not have a rear power valve. you will want to go 8 to 10 bigger in the rear then the front. But the rear has nothing to do with you lean problem. Also, what plugs are you running. I would look into some NGK 7s, maybe even 8s. Bigger number, colder plug.
Timing really should be OK at 36 total, but you may try pulling 2 degrees.

[CarlC]

Those heads like 32* total, all in by 3200-3400 RPM.

72 jets on the primaries is in the ballpark with that carb. I've run mine as lean as 69 with a similar setup. Your secondary stagger is a bit on the small side. Should be 4-5 sizes larger.

It's particularly easy to damage the GM Vortec style intake gasket if a bit too much torque is applied to the bolts. This could easily cause a vacuum leak, though it may only apply to 1-2 cylinders. Ask me how I know....

[zbugger]

.... Ask me how I know....

Ok, how do you know?

[CarlC]

Damaged 1-3 port seal causing lean condition on #3. 5-7 seal was not well sealed either. Spark plugs told the tale.

Another friends engine, with poor standard type intake gasket fitment, would create a vacuum leak on the valley side on all ports. Headers glowed quite nicely when the gasket seal let loose.

[CoryM]

Ya, your jetting is a bit on the light side, but not enough to make your headers glow unless you are at WOT the whole time. Timing looks good to me. The only thing that suprises me is that your engine temps are so low. Usually lean will make EVERYTHING really hot. You must have a good rad and fans on there.
To make the headers glow you are sucking air, or something is not right in the carb. When you say your intake was leaking was it leaking coolant/oil or did it have a vacuum leak? Grab some carb clean that is flammable and spray it around the intake/carb. If there is a vacuum leak the engine will pick up rpm when you spray near it. Thats usually the best way to find a leak on a sbc. Make sure your vacuum accesories dont leak as well.

[79T/Aman]

check for header leaks if your headers are glowing that far down that you buddy can see them from his car you may be introduceing air in the exhaust causing an after burn, you may also have a lean miss that will cause raw fuel to be exhausted and in combo with a lean condition that cause a hi exhaust temp will it will burn that raw fuel.