Ran across these pics, interesting differences in design..

 

It's easier to compare when both photos are oriented the same.

The W30 intake is dimensionally identical to the iron intake. The wider runners on the O4B are interesting, but are they the same internal height as OEM or not? Cross section area is what matters, and it looks like the ports in the heads are the limiting area.

 

Thanks Joe…

The O4B runners are deeper, and the flanges probably seal better…

 

O4B clearly has wider runners that narrow as they get closer to the heads. Wonder if they thought that somehow helped. Also it appears that the lower plane does not have as tight vertical curvature before entering approaching the heads.

 

the Edelbrock "4B" intake series date from the mid-'60s & were basically aluminum versions of factory cast iron intakes - I bet it's very close to a 1966-'67 390390, but can't find a picture
here are some factory cast iron intakes that have the "swelled" feature on some intake runners

 

Here's a 390390

 

Nice pics of the early intakes. The O4B measures 3 3/4” from the carb flange to the floor, I wonder what the Winters W30 measures?

 

Although I’ve never done a true back to back, I’ve done similar combinations with both of these intakes. Never saw any real differences in power.

 

My thoughts exactly. This holds true for Pontiac factory cast iron vs aftermarket dual plain. Actual dyno testing proved the factory intakes did better up to 5500 RPM. Sometimes less is more.