This manifold was produced in the early to mid-70's and was intended to add fuel mileage and efficiency from idle to about 4,500 rpm's. This was in the middle of the oil crisis and even if you could buy gasoline, it was very costly (in relation to bread and milk at the time). So, every effort was made to increase efficiency.

I used these manifolds on two different 302 Fords during that period with good success. The runners are very small to accelerate the mixture and fill the cylinders at lower rpm's. The throttle response is incredible along with manifold vacuum, but she's all done by 4,500.

It would seem a shame to me to use this manifold on an oval port build, because the same end result could be easily achieved with peanut ports which would otherwise be a bad choice for a strong street motor. I'd save the ovals for a 5,500-6,000 street project motor using a Performer or Performer RPM.