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Discussion Starter #1
hey guys, well i put a BG carb from a big block i had onto my GMPP 350 WITH 385 HP. I have backed out the idle rpm adjust, and played with the idle mixture til i fouled my plugs (its been awhile so this old info i once knew is coming back slowly), hooked up pvc and vac advance, but the carb still wants to idle in the 1500-2000 range. any suggestions..other than switching to fuel injection!!!
 

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Any vacuum leaks? Is something holding the butterflies open? Did the carb sit for a long time? If so it may need to be gone through.
 

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hey guys, well i put a BG carb from a big block i had onto my GMPP 350 WITH 385 HP. I have backed out the idle rpm adjust, and played with the idle mixture til i fouled my plugs (its been awhile so this old info i once knew is coming back slowly), hooked up pvc and vac advance, but the carb still wants to idle in the 1500-2000 range. any suggestions..other than switching to fuel injection!!!
Is it a vacuum or mechanical secondary? Does it have a choke on it?
 

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My holley did that to me. It was because my secondary butterflies werent closing letting air through the carb. Just like mentioned above..I'd check that . Dont know how to adjust that on a BG though.
 

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My holley did that to me. It was because my secondary butterflies werent closing letting air through the carb. Just like mentioned above..I'd check that . Dont know how to adjust that on a BG though.
If it is a vacuum secondary or has a choke it will have a small black allen set screw in the base plate for the secondary side. If it has a choke it can also be staying up on the fast idle as well.
 

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In addition to checking for open secondary, look to see if the butterflies have holes in them. And a longshot, look on the bottom of the baseplate to see if there is a drilled air jet dead center of the 4 venturis.
 

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Discussion Starter #7
hey guys, ita mechanical secondaries, no choke. aleady checked and no vacuum leaks that i can find and no holes in butterflies. i was hoping to avoid having to pull it but it seems that the only thing left to do is to check the butterflies and see if they are closing all the way as everyone has suggested. thanks for the all the input, i'lll post the solution when id'd.
 
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