Originally posted by coldknock
Third line down under Features.
A lean burn most definately causes higher combustion temp. A liquid converting to a gas will reduce ambient temps in the immediate area, hence the ice on the intake.
That is a new description they added recently. I have a few older Holley books in my bookshelf and none of them recommend 390s for 2x4s.
I have used two 450s, two 600s, and two 750s. The 600s were about right for my 5.0.. The 750s were a bit too much. When I used the 450s, the mixture was lean all around. The idle circuit was insufficient, and the top end (PVCR area) was inadequate.