You are working on a very unique carburetor. They are special castings and most were used on 454 big block Chevy truck or motorhome engines. They take special parts and special gaskets, hopefully you bought one of our kits for it because over the counter stuff will not have the correct high flow N/S assembly and often gaskets are incorrect as well.
Those units used a full taper primary metering rod with a high limit adjustment for the APT. They were very precisely calibrated and generous for idle fuel delivery making them work quite well on the big 454 engines they were used on.
I have seen a few sitting on heavy duty 350 truck engines and pretty sure they were OEM, but most of those were used on big blocks.
The secondary side of the carb has a special system not found on any other units and they will have an internal vacuum leak if you don't use the correct gaskets above and below the main casting. I see a LOT of them rebuilt and sent here not working well assembled with the wrong parts........Cliff
