does anyone know the intake runner size of #993 casting heads? are 305 heads much different on the runners? i had a pair of #416's. im getting some dart heads that are 170cc's, i take it thats larger than the 305- #416 or 350-#993 heads?
I flowed and poured a set of camel hump heads and they were 165cc intake runners. And the new VORTEC heads are 174cc. If you want to make some nice power then you need around 170 to 180 cc heads....Don't get carried away though. 190cc and up require a taller roof on the intake runner. I have a set of Edelbrock E-200 heads and I had to buy an intake just for these heads.
In addition to having the ports raised 0.100" over standard SBC heads, those E-Tec heads have the same intake bolt pattern as Vortech heads. That's why you have to use a manifold made for Vortech heads, regardless of runner volume.