air fuel adjustment

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air fuel adjustment

Postby beakerztoyz » Sun Sep 16, 2007 3:00 pm

Hi all im trying to set the air fuel mixtures on my edelbrock carb {the two screws on the front} I know you are supposed to use a vacuum gauge and set them so they have the most, i think question is should the gauge go to the intake or the carb. tried on the intake and it never seemed to change am i doing this right? thanks T.J.
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1980 Pontiac Sunbird


Postby PeerStalkHawk » Sun Sep 16, 2007 3:57 pm

First turn the screws in or out equally to get highest idle speed and readjust speed to about where you want it. Hook up your gauge to the full time vaccum port on your carb. Adjust the mixture screws in out out to get just highest vaccum and no further. Re-adjust idle speed again to get best vaccum within your desired rpm. Then try and find a compromise between best vaccum and leanest idle mixture setting, Turn in lean to just drop point and back it out just enough to get best vaccum too. Its actually best somewhere in between the two methods. The vaccum method can make it a bit rich by itself depending on cam profile. Also check throttle response at slight variation in rpm as throttle blade position can make off-idle transition better or worse. Run idle lowest speed that still gives good vaccum and idle quality. Maybe about 850-1000 rpm for mild combo in park. Basically, you want the lowest and smoothest idle speed possible with a smooth,instant off-idle transition. Make sure timing is really close before fine tuning and that it is not advancing(the mechanical advance) while adjusting idle speed and mixture. Hope it helps you out.
-Dean
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