Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
How much intake manifold vacuum do you have at idle?
The reason I ask is, I had a good brake on a 1971 Chevelle, then I rebuilt the engine, put in a high lift camshaft, then the brakes were really poor and I found out by some research about the vacuum. So I hooked up a vacuum gauge and it was 14 inches at idle, supposed to be like 19 inches. I was considering installing a vacuum pump like on a diesel but I sold the car before I did.
So, if the vacuum is low, it could be the reason for the poor braking and it don't have to be because of a high performance camshaft, it could be just retarded ignition timing. If the vacuum is low, check the ignition timing and if it's retarded, advance it some, as a matter of fact advance it as far as you can go without the engine starting to run poorly, just to see how much vacuum rise you can get. Anyhow, let me know what the vacuum is for now.
Was the intake manifold vacuum low?
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