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| Carb help https://mail.slantsix.org/forum/viewtopic.php?t=67215 |
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| Author: | valleyguy [ Sat Apr 29, 2023 6:56 am ] | ||
| Post subject: | Carb help | ||
Had a local guy "rebuild" my old Holley 1BBL for my 63 valiant.(using aftermarket kit); Well it runs, (idles well), but bogs down when I open the throttle. (Plugs, wires, fuel delivery, timing etc are all ok) Likely culprit?? Thanks
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| Author: | wjajr [ Sat Apr 29, 2023 6:32 pm ] |
| Post subject: | Re: Carb help |
Accelerator pump shot too small. Main jet to small. Idle mixture too lean. Vacuum leak between intake manifold and carburetor base causing a lean condition in idle circuit, transition circuit, running on the main jet. When the throttle plate opens the A/F mixture goes lean for a moment causing a bog. This can be caused by the transition circuit being too lean which is controlled by the idle mixture screw. Or a bigger shot of fuel from the accelerator pump is needed to make the transition from idle/ transition to main jet. Make sure when the throttle is opened there is a nice shot of fuel squirting into the carburetor. Engine off, remove air cleaner, look down into the carb, and open the throttle by hand and see what is happening. Look for a nice shot of fuel, or small dribble. Small dribble indicates accelerator pump is not working. Gently seat the idle mixture screw, and then back it out 1 1/2 turns to begin. Screw it in or out at 1/8th turns until you find the highest vacuum reading. That may cure the bog. If there is no response to engine speed when adjusting idle mixture screw in or out, chances are good that there is a big vacuum leak between the carb and intake. Sorry this answer is so disjointed and choppy. My head seems to be somewhere else tonight. |
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| Author: | valleyguy [ Sun Apr 30, 2023 4:24 am ] |
| Post subject: | Re: Carb help |
Thank you! |
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