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Thread: Engine Vacuum
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12-07-2017 #1
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Engine Vacuum
I have a small block 427 with a Howard's Cam giving me about 5 inches of vacuum at idle. When I rev it up my vacuum increases to 22 inches. Upon checking all vacuum ports on my quick fuel carb they all read the same - 5 inches at idle and 22 when I rev it up. Shouldn't the vacuum decrease as I rev the engine? If so, what would be the problem that causes the vacuum to increase and how do I fix it?
Thanks!
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12-08-2017 #2
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If the engine is not under load, meaning, you're just revving it up while standing still, the vacuum reading will go up with RPM. This is normal. If you were to do the same thing on the street, you would see vacuum drop at WOT.
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