Hi, does anyone have any info of plenum mods for the SB Air Gap similar to the LD 340 stuff from decades ago? I've seen vids on some improvements from divider mods on SB chev AG's, just don't want to jump in at the deep end without knowing what to expect. Thanks.

Smooth out, blend and remove center divider and run a 1" open spacer worked best for me....Tried a lot of different things, and that worked the best.

I have always ran a 2" spacer on Air Gap manifolds on my small blocks.

I've used 2" open and 2" Super Sucker style spacers with success. I usually just radius the divider

I did see on a Facebook group post where someone used a modified 4 hole spacer in a different manner. The spacer was turned in to a three hole spacer, one side was opened up to match the intake, where as the deeper side of the intake\, the spacer was left as a four hole. They also dimpled the floor with a ballnose end mill. If I can find the pictures, I will post them.

Cheers