I've got a big cubic inch small block with an LS firing order. What should the primary tube orientation be where they enter the collectors?

This is something people have different theory on, some say cross pattern into the collector, so like corner to corner. And others say you should go rotationally, around the circle. I have not seen any appreashable difference. I would just do whatever works best to fit the headers and look good, and gets you equal length.

Thanks Will, I'm going to do just that.

George Klass (that old guy that used to work for Accufab) told me a while back that he prefers the rotational pattern...says on the SBF bigger inch stuff that they see on average 40hp improvement over other styles. But there could be more to it that I'm not being told. 40hp sounds substantial.

Perf Weld does this and so do others, Take a look at this. Read down a ways, they want the firing pulse circular to scavenge. https://www.hotrod.com/article...anifold-header-tech/