Fuel System: Carb Adjustment

[aftontrix]

Is there a certain number of turns on the two screws of a Bendix Stromberg 2 barrel carb mounted on a 289 that will get it close to the correct adjustment? The carb was rebuilt by one of the Studebaker Drivers Club Vendors. It now idles rough. I had it close at one time but it started running rough so I started twisting the screws. It turned out my plugs were fouled so I fixed that but now cannot get the carb right for a smooth idle. Thanks for any assistance.

[53k]

I always turn the two screws down until they bottom out (but don't force them). Then turn each one out and one-half turns. Start the car and adjust each screw slowly until the idle is smooth. The engine should be warm when making the adjustments.

[r. hill]

You may have a vacuum leak at the base of you carb. That would cause a rough idle

[BrianC]

Few yrs ago i had vac leak at the base of the carb, replaced it. Bring your fast idle up a bit before you tune the idle screws. As 53k said, turn one in all the way till the engins stumbles, then back out 1/2 turn. Do the same on the other side. Turn your fast idle back to see if it stumbles or is rough. Make sure the timing is set properly or you'll be chasing your tail at the carb. Ive had some issues with my 63 Hawk last couple of days, flooding. I tend to work the carb adjustments and the timing at the same time, get a reasonable or your best idle and then see if a timing tweek will smooth it out. Important to make sure the float level is correct.
Another approach is to set the screws out 2 turns and start from there with idle and timing.

[Bud]

I turn the idle mixture screws in until they just touch the seat and then back them out about 2 turns. Tightening the screws will score both the face of the screw and will distort the seat in the base of the carburetor which will make accurate adjustment impossible. With the engine warmed up and the idle speed somewhat close, turn each screw in until the engine just starts to stumble and then back it out around 1/2 turn which should make the mixture go rich, then turn the screw back in until the engine idles the smoothest. You will have to do this a few times until the mixture is correctly adjusted. Bud

[BrianC]

Was having issues with my 63 Hawk carb. After all the usual checks, timing, mixture , idle etc. and i cured the flodding issue, but noticed all of a sudden a rough idle. The simple error was that at some point must have moved the thermo choke setting. I re-set it to just two notches ahead of centre and problem solved. Sometimes its just something simple that frustrates you to scream .