Glowing red header tubes

[greywurm]

I've posted a couple questions over the last month or so as I've been swapping in a 72 350 in my 71 long bed and everyone's help has been great.

Got the truck back from the muffler shop today - installed 2.5" dual pipes with black widow mufflers. Sounds GREAT.

Anyways, it was dark out and I knew I needed to do some tuning, and I was too anxious to wait so I figured just dive right in. And glad I decided not to wait because I might not have noticed as quickly what I saw if during the day...

Header tubes for #1,#3,#6 and #8 glowing bright red in the dark... a little off colored under light, and a little smell. Not sure how i'd describe it but I think its just from the grease that rubbed off my hands burning off.

I was originally planning on messing with the fuel because it would stall out under load and I've read that the edelbrock carbs dont like too much pressure. I'm not sure if its related, but if its getting too much pressure and is flooding the carb, couldn't it cause a rich mixture and potentially detonate after it leaves the exhaust port?

Disconnected the timing advance on the HEI and yep, my timing was a little retarted... 4 degrees after. Set it to 4 degrees before, but I didn't notice a decrease in the glow. Maybe I was impatient and should reconnect the advance and check for glow again, but it was getting late so I didn't was to upset the neighbors anymore.

What else should I be thinking of checking? My gut is telling me its timing since its 2 cylinders on each side of the motor, not all on one side, so I don't think the headers are clogged. They came with the motor, so they are used and I installed them myself. Maybe not a good job?

I am lacking the inner bolts to the outer tubes because I cant get either header bolt design I have to clear the elbow of the tube to go in the heads, so I could have a poor seal letting air in for detonation in the tube... But being that its also happening on #3 and #6 where I do have bolts, I am currently ruling that out, for now.

I did notice occasional flames out of a couple exhaust ports when I did a test run of the engine on the stand to make sure it would run (only for ~ 10 seconds each time). I didn't think much of it at the time, but if it is timing, then I was 4 degrees after then as well.

What do you guys think?