6 On the normally aspirated combination, we relied on a 750 Holley HP series carburetor. Making our life easy was the fact that the Holley in question featured Percy’s Adjust a Jet system. This slick system allowed external changes in air/fuel without resorting to bowl removal to change jets. We wanted to run the Edelbrock Performer RPM Air gap, but time constraints forced us to run the stock cast-iron (remember those?) 4V intake manifold. Not bad (in terms of airflow) as far as factory intakes, the iron 4V was certainly heavy.