The 2 brass screws with springs that are threaded into the aluminum body of the carburetor are idle mixture screws, the screw behind the choke should be a fast idle adjustment, and the screw near the throttle cable is curb idle adjustment. The PCV hose that is connected to the air cleaner housing should not have a PCV valve on the other end, that hose admits fresh air into the engine crankcase, the PCV valve and hose suck the combustion blowby gases out of the crankcase and re-burn them. If it's running well enough for your use then "if it ain't broke, don't fix it"
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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