Join Date: Sep 1999
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Re: stock carb vacumn
What I'd do is hook up a hand vacuum pump, measure how much vacuum it takes to get the secondary fully open, and keep the vacuum on it to see if it leaks down... When you have measured the amount of vacuum that it takes to fully open the secondary, hook up a vacuum guage on the engine, and drive the vehicle, and see if you are getting enough vacuum to properly operate the vacuum secondary... The problem might be the vacuum mechanism on the carb itself? A vacuum leak anywhere in there could cause you to lose enough vacuum so that it won't work right... Assuming that there's a rubber vacuum line that goes to it make sure to check it for cracks or wear that could cause it not to hold vacuum.. hope that helps...
[img]/wwwthreads_images/icons/cool.gif[/img] '79 Suburban 4x4 454, 6" lift, 35x12.5s & '85 GMC S15 4x4