You don't have enough timing in and fuel is still burning out the exhaust ports. This problem is common on a new cam break in and is why most folks recommend using beater headers/manifolds you don't care about for the cam breakin. (i.e. don't throw your $400 ceramic coated Hookers on there until after break-in and things get tuned in right). You maybe too rich (or less likely too lean) but I think the timing is the biggest contributor.....

I would suggest giving it more advance and finish your break in... if the exhaust still glows don't worry about until you finish the break in. Once you get the mix and timing dialed in right it won't be a problem any more.

-Chris

^^^^ BTW: Frisco types faster than me