Yea it is a vacuum secondary's. It got a little backfire thru carb when pushing on it can't figure it out, is there anyway of telling if I got a hydrulic cam or a flat tap pet. Cam is a little big I guess when I idle brakes are hard , put a vacuum gauge on her today an at idle got 6 on gauge. It needs a stall convertor just don't have the power it should have. Will a set of aluminum heads bring her around,