Oil Injector and Check Valve Question
 

Hello,
This is my first post so I apologize for any possible missing etiquette. I have a non-turbo 88 convertible that I recently purchased after sitting for a long time. I have followed several procedures to get it running and it seems to start easily now and almost idle. At present I am going through some of the systems in order to insure their working condition. I removed the oil injectors and check valves and found 3 of 4 to be non-working. I soaked them in ZEPRESERVE and carburetor cleaner and after a little effort they are now all working (vacuum seals and pressure allows air to flow) with the exception that the 2 integrated check valve/oil injectors that feed the rotor housing directly allow a slight amount of air when sucking on the check valve vacuum nipple.
So my question mainly is their functionality. (Keep in mind I have a non-turbo so I don't know how any of the following presumed functionality would apply if no vacuum source is available). The vacuum feed from the upper intake plenum (surge tank?) tee's off to 4 vacuum hoses, 1 for each check valve. I would assume under most (if not all) engine operating conditions there is a vacuum in the plenum. If so, essentially these check valves remain closed and therefore do nothing more than prevent oil from being sucked into the upper plenum. Additionally, if there exists a differential pressure created by a lower pressure in the lower intake manifold than the upper intake plenum, then air would flow through the injector into the lower intake manifold (possibly to flush the injector ??). I can't picture that scenario, but I can't imagine the benefit either.
Specifically, if I have a slight leak in the rotor housing injector check valves I would assume some or possibly all of the metered oil to the injector could get sucked into the upper plenum and end up in the combustion chamber preventlng lubrication of whatever they are intended to lubicate (rotor bearings ??).
Thanks in advance for any information. Jeff

The oil injectors are not hooked up to vacuum. The nipple they are fed from is actually a metered air source (before the throttle plates), so air is actually being forced into the injectors to aid the injection process. If you trace the path from the nipple through the plastic TB spacer, you'll see it ends up at a small hole directly before the throttle plates (but still inside the TB itself).

Thank you, thank you. That changes basically everything in my assumptions. So basically, if the pressure before the throttle plate is above the pressure in the lower intake manifold I can see how that would aid the flow of the 2 manifold injectors. I don't know what pressure condition exists with the rotor housing injectors, so can I assume a similar condition/operation? Also, I am assuming the OMP isn't really producing enough pressure to blow oil past a slightly leaking check valve with atmospheric pressure on the other side, but this is the condition that concerns me with the rotor housing injectors if they are not seeing a low pressure condition like the lower intake manifold injectors. In other words--what can happen in the check valve isn't sealing perfectly (i.e. a noticable difference in flow in the two directions, but not a perfect seal)?? Thanks in advance, Jeff