I have a freshly rebuilt Pontiac 400 motor in my 1968 Firebird. One minor snafu during the assembly is I forgot to install the oil pump intermediate shaft before the oil pump, so I ended up having to file off the "ears" from the intermediate shaft and install from the top.
I installed the motor in January of this year, and shortly after installing, poured 5 quarts of oil over the valves before installing the valve covers. I then proceeded to prime the oil system using a priming shaft hooked up to a drill, which I ran counter-clockwise for approximately 5 minutes. The oil system built approximately 60PSI of oil pressure, and I could clearly see oil coming out of the pushrods and into the hydraulic lifters. When I spun the priming shaft by hand, I could feel "hydraulic" resistance.
The project then got sidetracked for a couple months, and the motor was not actually started.
This month, I've started focusing on the car again, and decided to prime the oil system again before starting the motor up for the first time. However, now I can't seem to get oil pressure to build. When I spin the priming shaft by hand, I feel zero resistance-- it's as if the pump is just pushing air around. I've been very careful to make sure the intermediate shaft is engaging properly with the "gear" on the top of the oil pump, and that the priming shaft is engaging properly with the intermediate shaft. I've inspected the "gear" on the oil pump with an endoscope and it seem to be in tact. Yet when I spin the oil pump with my drill, I get zero oil pressure, and a very "hollow" sound, as if the oil pump is just pushing air around.
Here's an audio recording of the priming procedure.
