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RichardJ · 03-18-2018, 05:14 PM

>> old 350 idled around 850-900, but the LS idles around 600-650<<

Why not check manifold vacuum with a vacuum gauge?

Check the booster. With engine off, pump brakes 3 or 4 times and hold pedal. Start engine and the pedal should drop as vacuum provides assist.

03-18-2018, 05:14 PM	#2
RichardJ Registered User Join Date: Apr 2010 Location: So Cal Posts: 1,491	Re: Brake booster question. 72 K10 >> old 350 idled around 850-900, but the LS idles around 600-650<< Why not check manifold vacuum with a vacuum gauge? Check the booster. With engine off, pump brakes 3 or 4 times and hold pedal. Start engine and the pedal should drop as vacuum provides assist. __________________ '67 GMC 2500, 292, 4spd, AC