I purchased a rebuilt Rochester B carburetor and installed it on a rebuilt '59 235. The engine has new valves, seats, springs, etc; was recently timed, and the valves were adjusted. The engine runs and idles smoothly. At idle speed, the vacuum pressure at the carburetor is only 4 inches of mercury. Specs in my '58 shop manual call for 17 to 21 inches. Any idea on what's wrong?
The gauge is new and seems to work correctly. The vacuum hoses to the windshield wipers and the distributor are removed and plugged. I do not currently have an air filter installed on the carb, but I don't know that it matters. I could not find a spec on how tight to torque the nuts holding the carburetor to the manifold, so I torqued them to 20 ft-lbs. Finally, adjusting the air/fuel needle valve does affect the vacuum pressure. It stays constant at 4 inches. At higher RPM (approximately 2000), the vacuum pressure increases to 15 inches.
Thoughts?
