Exhaust Manifold Bolts (Hexagon Head). 1.1/4" Hexagon Bolts For Cast Iron Manifolds. 1" Hexagon Head Bolts For Tubular Manifolds. RV8-1.1.1 Rover V8 Engine. OUR ROVER V8 EXHAUST OPTIONS. These Are Sized To Fit Standard Cast Iron Systems To The Rover V8.