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Rich a/f and Fuel smell on decel

779 Views 4 Replies 5 Participants Last post by  CarbGuy
I have a LM-2 on my cousins 396 70 Chevelle and i have a good a/f all except for decel. WOT is 12.8,cruise is 13.5(a little rich),idle is 14.5 but on decel its low 12's for about 2 seconds and there is a smell of raw fuel. Any ideas?
4779 750 Holley, stealth intake, and factory cowl induction.
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Idle mix being rich will do that
High vacuum with throttle blades closed = extra fuel on decel. This is one of the many drawbacks of a carburetor vs. electronic controls. In OEM situations fuel is leaned out or shut off completely during decelleration to increase fuel economy. Carbs always work the opposite way.
Make sure your transition slots are not overly exposed, .020 or looks like a small square when you turn the carb over.
The first two things to check would be your float levels, and your throttle plates. Make sure all 4 throttle plates are open the same amount (no more than .020" of the transfer slots exposed).
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