i put a new cam/lifters in last week and just now had some time to start the motor for the break in. And the number 7 header tube was glowing red. what would cause this? it didnt happen before.
i ran the motor for about 4 mins then turned it off. any ideas? timing?

Check the timing, you need to advance it on break in but they all should have been glowing. You need the timing to be all in at 2000, that 35 degrees, or unburnt fuel is going to be burning in the header tube .

Intake leak at #7 ?

And doing cam break in you should take out the power valve and go up 8 jet sizes.

Years ago when I first installed my 440 I had a similar problem. #6 header tube was glowing red during cam break in. I shut it down and started searching for a leak. What I found in my situation was the rear carb stud wasn't threaded far enough down to properly seat the carb allowing air between it and the manifold. A new stud cured the problem. Something to look at.

On a stock BB intake, the power brake booster is connected to the #7 cylinder runner. Could be a power brake booster leak.