Vintage aluminum intakes. Q&A
I ran an Offy Dual-Port 360 on my '69 340 Swinger years ago. Good street manifold at the time. The theory was good: small cross-section runner portion kept the primary intake charge at very high velocity for good cylinder filling; larger cross-section runner was isolated somewhat from engine heat so provided a cooler secondary charge when the secondaries kicked in. The drawback was at the higher rpm ranges due to the total reduced cross-section due to the material separating the primary and secondary runners.
40-year newer technology makes for better manifolds available today.
