Dave_Mustang_50 2 Report post Posted August 30, 2006 I have a 351c thats either got a vacuum leak, or not making enough. I know its got a cam, a/c and power disc brakes up front. How can I check to see how much the engine is making and check for a leak? I`m leaning toward a leak since its gotten much worse in the last 2 months. Thanks for any info/replies. Share this post Link to post Share on other sites
bnickel 10,004 Report post Posted August 30, 2006 put a vacuum gauge on the power brake port on the back of the intake. that will tell you how much vacuum the engine is pulling. a good rule of thumb is that street cars with power brakes generally need at least 15" of vacuum to run the brakes. a vacuum gauge is also a great engine tuning tool. the best way to set the timing and the idle mixture/idle speed on the carb is with a vacuum gauge, adjust until you get the highest vacuum reading on the gauge and then fine tune it from there to get it perfect. to check for a vacuum leak grab a can of carb cleaner and start spraying it all around the gasket sealing surfaces of the intake and carb and also around all the vacuum lines on the engine and whatever they connect to, when the idle changes after you sprayed a certain area you've found your leak. Share this post Link to post Share on other sites
