Ok, this is what I use rather than welding or filling in the SD/M1 carb flange.
You have to lay the gasket on the manifold and grind out and then contour the flange to match that gasket. If you don’t do that, it will NOT work.
That channel that goes all the way around the bores MUST be open to manifold pressure all the way around. Most guys just bolt them on without making the flange match that gasket.
This is actually an anti-reversion/shear plate combo. It works very well. I no longer weld the carb flange up. I use these and make the flange fit that gasket.
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This is a MagnaFuel MP-5006 and its for 1.750 throttle bores. If you are running 1.688 throttle bores they make a different part number.
