Wilson Manifolds shear plates are designed to maximize performance of engines using tunnel ram style manifolds. They incorporate a 5-degree taper in the bore to improve flow and feature a specifically sized anti-reversion groove machined into the bottom of the plate to help turn back reversion pulses. The extended portions of the plate also block reverse flow and help to atomize fuel, reducing puddling in the manifold. This design helps improve signal to the carburetor and flatten the fuel curve. These plates are precision machined from billet aluminum and are anodized black purple for durability and corrosion resistance. All shear plates measure 1/2" thick from manifold mounting surface to carb mounting surface and are available for 4150 carbs. as well as 4500 and Split Dominator