Vacuum Leak

Alright, I have tried spraying Carb Cleaner around the intake & Carb, does anyone have any more tricks for finding Vacuum Leaks? How about the most likely or unlikely places you have had them?

I recently had a vacuum leak at the carb throttle shaft.

At idle might run some propane in thru the PCV hose and see how it affects the eng. Not sure if it'll speed it up or down if it's lean from a leak but kickin out ideas & someone will know if it'll help you or not

If your talking about BB I couldnt get my carb to act right (acted like a vaccum leak) sprayed carb clean around intake and carb but I couldn't find it either. Took off intake sprayed head and intake sealing surface with copper coat and reinstalled car runs better than it has in a long time and carb acts right. Point is I couldnt find it (possibly under intake from cam valley?) but I recleaned and resealed intake tract and took car of it. You may have to put the elbow work in.

I had a guy brought me a 69 Camaro once, ran fine under power but missed at idle. He had thrown everything but the kitchen sink at it. I told him it was a vacuum leak, but he argued that he had replaced the carb base gasket and the intake gasket. Its still a vacuum leak I told him. Pulled the intake back off, looked inside it, and found the leak. Someone had used a bolt that was too long to hold the coil bracket on the intake, and made a nice hole under the bolt. After putting some sealer on the bolt and putting it all back together, it ran good. (As good as a 69 Camaro will run, anyways)

I found a pretty signifigant leak at the secondaries throttle shaft. The holley tech guy said there is always a small leak there that is acceptable (50 rpm raise from a shot of Carb cleaner. When I dowsed it, it killed my engine so I am thinking about a new base plate. Thanks for all the ideas, love to hear some more about pesky vacuum leaks!!

#1 on your hit parade should be vacuum lines - including PCV and brake booster. Plug them off one at a time and see if the "HG#'s go up.

I have been told the same thing that the secondary shaft is often times loose enough to leak but does not cause a problem.

Surely, you or a friend have another carb that you could swap to test. I would offer if you were nearer than a few thousand miles.