BBC 540 won't idle down
This is a mild 540 with 9-1 comp. I am running a Comp thumper roller cam with 32 degrees of total timing, an Edelbrock Air Gap and a 870 street avenger. The floats are set and air screws are almost all the way out. That is where the best idle is but I can't get it below 1000 rpms. It wants to die out unless you give it a little gas.
Any and all help would be appreciated. Thanks |
You have an air gap in your air gap, somewhere.
Check for vacuum leaks. New combination? Were the heads milled? |
This is a new combo. The heads were not milled. Everything is brand new.
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Yep a vacumn leak is likely to blame. Had a vacumn gauge on it yet?
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Haven't had a gauge on it yet. That's next on my list. It seems like their is plenty of vacuum, it runs power brakes with 9" booster with no problem.
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Originally Posted by landon718
Haven't had a gauge on it yet. That's next on my list. It seems like their is plenty of vacuum, it runs power brakes with 9" booster with no problem.
You have a leak somewhere. Set the butterflies back to factory spec and the needles at 1.5 turns out. See where your idle is then. |
Try to completely cover the carb with your hand and see if it dies.
If it don't die then you know you have a leak for sure...but it still could have a small one even if it does die. Maybe spray carb cleaner along the intake /head surface and see if the thing speeds up. I've also heard of people using propane to find a leak but never tried it. Could be under the carb too. P.S. The idle screws on a Holley metering block control fuel not air unless I am misunderstanding your post. |
I found that the 4 holes in the intake that are not used with aftermarket heads were leaking a little bit. Don't know why, there is nothing under the holes. I closed them up and no more leak.
Thanks, for all the input |
Glad you found it and it was simple to fix.
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