Let's Build a 416 with Cast Iron Heads and Manifolds

rumblefish360 said
Porting of the intake manifold, exhaust manifolds and heads to their maximum abilities is the only route. OEM heads can go pretty far. I’ve seen 275 from the letter heads. This will be reduced significantly with the iron manifolds. Once you have the intake and heads ported, have them flow tested together to see not only how well they flow together, it’s how much and where the best air flow happens. Only from there can you even consider a camshaft.

Select your intake and exhaust manifolds wisely.

Manifolds are part of the exhaust, so restrictive ports or manifolds equate to about the same. To overcome that a bit the exhaust seats can be cut to 40° which aids the low lift flow. This aids blowdown to get the scavenge cycle going strong.