I just purchased a offy quad intake manifold (#5416). I also purchased a rebuilt Holley 390 to go with it. It's going on my stock 250 that was just rebuilt. Other than header pipes, it is completely stock.
I just finished installing it with the primaries inboard and it runs terrible. Soo, I decided to switch it around and put the primaries outboard. It still runs rough. It won't even idle without some help. Question: what's the proper orientation for these four barrels?
According to the instructions that came with the offy manifold, the primaries are supposed to be inboard (toward the valve cover). It also mentions that no jetting changes need be made with this setup. Does anyone else have this setup and could give me some help? I've tried various idle mixture settings with no help. The vacuum ports were all hooked up to various items. I know it's not electronic because it was working great with the one barrel rochester just a few days ago.
