Finally got the engine in my challenger(new engine). And noticed that I had 3 header tubes glowing red. It was previously on a break in stand with some cheap 1 3/4 headers and mp elec. dist. Now its in the car with 2 super comps. and msd pro billet and 6al. When it was on the stand I never noticed any probablems with "glowing" header tubes. Is my timing off? Or just running lean? Its a 500ci with a 6bbl set up. This may be a stupid question but how can i adjust the mixture? The one screw i've found on the center carb doestn' do anything when turned.

if those tubes are glowing at idle, I would say too lean. you will need to remove the front carb to get to where you can remove the float bowl on the center carb.
glowing like that I would jump 2 to maybe 4 jet sizes larger.

glowing while driving it could be a lean condition or to much timing.
more info is needed..

yes check timing but LEAN like my oxy/acet torch when I add oxygen

I cant drive the car yet, no body panels. Just getting it together. Haha. But it does it when i hold it just past idle at a steady rpm. I can watch the tubes start to get red and when I let it idle it goes away after a few seconds. Thanks

Yep -- way too lean. Run it like that and you'll have over-heating probs too...ya need to richen her up.

(retarded) timing. See what your initial is & that it is advancing. See that the fuel level is at the bottom of the sight plug on the center carb.

Timings retarded or very rich mixture. Start with more timing advance,are you using vaccum advance? If not, you should.

Intial timing looks about 15 deg. advance. Is that to retarded or is it a fuel related?

your initial is fine. run it up a bit & see how much you have at the point where its glowing red. EDIT note the timing & the rpm. & if that's close to good then we can move on to mixture but with that being said you did change the DIST & with a six pack I'm sure that it wasn't changed.

There is no change still 15 deg. I cant see the tach but i'm guessing about 1500 to 2000 is when they get red. What rpm should i see a change for the advance? The distributor has the heavy springs in it so i guess i should go lighter?

You run it up to ~ 1500-2000, what is the timing at that point. EDIT Am I reading this right that when you run it up it's still at 15?

I've seen this before when the head gasket was on backwards. Depending on which gaskets you used. Some have a front and rear to them.

Fix the timing 1st. Should be lots more than 15 at 2000 RPM.

I built a 500 inch 440 and had to jet up the center carb on the out of box new repro holleys. due to same problem you are having. I also popped out the plugs on the end carbs to tweak the mixture screws just a hair.

Not the case. If a cylinder is very lean it will misfire creating less exhaust heat. Very rich mixture will still be burning as in goes out the port creating alot of heat. Advance the timing lean the rich cylinders and the problem is cured.

but, don't forget, if it's not timing, lean enough to still burn without a misfire, will also burn hot.

so...could be lean, could be rich, could be timing.