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| | | | Joined: Dec 2006 Posts: 1,154 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,154 | Manual choke....Rochester B...235.. air mixture screw CCW is this the correct direction for lean? .....CW is this the correct direction for richer?....seen it done both ways out in the driveway...my vote is for CCW for leaning out the mixture of air fuel...maybe I'm wrong??? But he has sooty plugs his way...?
| | | | | Joined: Oct 2012 Posts: 233 'Bolter | | 'Bolter Joined: Oct 2012 Posts: 233 | CCW is richer
CW is leaner
1 1/2 turns out is starting point.
1953 Chevy 3100 261 and SM420 53Chevy 31001953 Mack Firetruck 1972 Porsche 911 1986 Honda Goldwing
| | | | | Joined: Dec 2006 Posts: 1,154 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,154 | I swear somewhere here on the forums it was stated exact opposite ...in fact it stated screwing,"out the screw makes it leaner." ? Glad I didn't bet money. The article I read changed my mind I thought I was doing it wrong .....bad information.
Thanks! | | | | | Joined: Jun 2010 Posts: 117 Shop Shark | | Shop Shark Joined: Jun 2010 Posts: 117 | CW tightens the screw until it bottoms out in the base of the carb...leaner
CCW loosens the crew until it come out of the base of the carb...richer
That's the way I understand it. I am new to this and could be wrong too!
Last edited by jaydee5150; 09/03/2016 7:57 AM.
1955 Chevy Cameo
235 engine
3 speed transmission
| | | | | Joined: Nov 2002 Posts: 2,766 Carburetion specialist | | Carburetion specialist Joined: Nov 2002 Posts: 2,766 | Different types of carburetors handle the idle mixture control in different ways.
The Rochester B screw is located after the air and fuel are mixed, thus CW (in) is leaner, because CW reduces the volume.
Other carburetors (many older Zenith and some Strombergs) meter air with the screw rather than the mixture of fuel and air. In this case, CW (in) is richer because it reduces the amount of air.
And then you have the strange case of the two-barrel Schebler, which uses knobs instead of screws for the idle adjustment. One is right-hand thread, the other left-hand thread. Thus using one CW is richer, the other CW is leaner.
Rather than read what has been written, sometimes in error, on the internet; always best to look at the idle circuit on the carburetor in question. Easy to tell by looking how it is going to work.
Jon.
Good carburetion is fuelish hot airThe most expensive carburetor is the wrong one you attempt to modify. If you truly believe "one size fits all," try walking a mile in your spouse's shoes!The Carburetor Shop | | | | | Joined: Dec 2006 Posts: 1,154 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,154 | Thanks for your help as always...Jon...! | | |
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