Hello. I just picked up a M1 single plane and don't understand why you are using "adaptors" or modifying the shape when it's drill for a Holley carb anyway?
The M1 has that opening designed for spread-bore carburetors, If that was the style carb you’re using you’d just remove the 90 degree edge, round the transition of the sides of the opening, round it over,blend it all with the roofs of each runner. If you’re using a square-bore carb you’d still do the same, or weld and shape it to a square-bore opening (or epoxy and shape like others have done) Some have the will, the tools and time, others maybe the money to have it done, others may just prefer to bolt-on and go. Your choice:)
