We have the capability to machine your new MR-1 Pontiac block for a 50mm or a 55mm camshaft. The 50 mm cam tunnel is available for FREE when you order your new MR-1. The 50 mm needle cam bearings are an additional cost the set. 55 mm cam tunnels are also available at an extra cost. We can add this feature to your new MR-1 Pontiac block or we can machine it in later if you chose to upgrade down the road.