Keep in mind that the two carbs are dimensionally identical (in terms of air path way) except for the choke horn size, which is about 25% larger in area.

The size made the difference I noted, but as to filter, material is as important here as any other application. I was only highlighting the fact that proximity was critical.

At one time, I used a home made filter that had foam sides with wire reinforcement, that actually used the hood as the cover in an attempt to keep the cover as far away as possible from the choke horn.

I didn't mention that the testing was done with 2.3 heads and manifolds on an Air Flow Bench. Three or four carbs were tested agains't each other.

Good racing.

Bill