Glowing Exhaust Manifolds

I used the big block Chev engines in our race cars ever since they came out in the 60s----headers get hot much quicker than exhaust manifolds and we learn quick not to "burn" a set of $2000 chrome headers. 1 thing is the plug firing before the exhaust valve is closed completely letting the combustion heat into the exhaust system (timing). The other is a lean fuel mixture. I tuned my fuel injected dragster using exhaust temp gauges in the headers and try to keep it in the 1100 to 1200 degree area for best performance and never see a red hot header. This is tuned to the lean side. Those manifolds should not be red hot so something is wrong somewhere.