Carb and Intake for 5.2 Magnum

My friend has a 71 Demon with a 318 Magnum. We did upgrade the cam a little but otherwise it has an A904 with a stock converter, a 3.23:1 axle.

It has the Edelbrock Air Gap for the magnum engine and a 600 Holley Vaccum secondary like the one you are describing. I think its the same one just in Zinc Dichromate instead of shiny finish. It has an electronic distributor that is a stock design one.

The carburetor is stock except for having a 10.5 power valve and a slightly lighter secondary spring. The distributor was re-curved by shortening the slots to get 15 BTDC up front and 35 total, and only the light spring with one link removed. This works well. The fuel mileage is something I don't know so much but I would say its in the 14 mpg range, so I guess 16.5 l/100km or something like that. Not sure you can ever expect too much better.