Glowing headers

Yes, timing it was, I put 75s in and took them back out to the original 71s.
The engine really likes 18-20 but doesn`t like to start at that, it starts good at 14-15.
No more glow.
curious of why so much timing was needed for break-in? and not needed now?
tight clearances?
Yep with no load @ 2500 the boosters aren't even dribbling yet, that I could tell.
The engine sounds awesome, but have to replace the rear seal, oh lucky me.
Thanks guys, you know who you are:D
Not to say that it won`t need tuned for load on the street, but that`s a while out.