This billet adaptor is used to install any Autolite, Holley, or MotorCraft 2V carb on a stock LARGE LOG cylinder head with a 1.75" carb bore. The adaptor comes with a custom billet insert, which improves ar flow and horse power, and two stainless steel Allen head cap screws for mounting (carb studs and phenolic spacers are optional). Gaskets not included. No machining required.