O.K. here goes. With a very large FWIW preceding it my thoughts on the pre-oiling situation.
Oil Flow:
In a standard configuration
oil comes out of the pump to the outside area of the
oil filter where pressure forces it through the filter element to the inside tube. Up the inside tube into the oil galleries and then back down into the pan. (drawings in my gallery as 428.jpg for a standard 428/solid lifters, 428Hyd.jpg for a 428/hydraulic lifters and 427SO.jpg for the 427/hydraulic lifters).
Opinion (just like a-holes, everyone’s got one and they usually smell ;-)):
No matter what the engine, a good deal of wear takes place on start when the moving components have minimal or no standing lubrication. A pre-oiling system, either accumulator or pump, addresses this and, even if minimally efficient, provides reduced start up wear.
Plumbing and backflow:
Backflow would appear to be present in any system that accesses the oil galleries directly. How much this would reduce the efficiency of a pre-oiling system would, I’m sure, be a combination of a number of factors that are wayyy beyond my simple understanding of the oil system.
Given the oil flow from the pump I think the ideal point to plum in a pre-oiling system would be a separate tap into the system between the point at which oil exits the filter and the first pickoff point of the oiling system. This would still have the backflow problem but I think it would be minimized through the design of the filter and the fact that the oil pump, in a non-rotating condition would also restrict back flow through it.
Second best would to plumb into the system at the return side of the cooler with a check valve upstream of the tap. The check valve would eliminate the back flow problem but wouldn’t be my first choice because of the failure potential of the check valve. While check valves are extremely simple in design it’s still a failure point being introduced into the system and a failure of the check valve would result in total oil starvation for the engine. Again, not often heard of but possible.
Third choice would be to plumb the pre-oiling system into a T at the point at which the oil pressure-sending unit taps into the top of the oil filter housing. This is a less efficient structure by retaining the backflow personality as described above but eliminates the potential failure point of the check valve.
Pumps vs Accumulators:
Using a pump system would negate the backflow concern because, even if it occurred, the continuous action of the pump would override it. What a pump doesn’t address is the ability of the accumulator to provide temporary oil supply during period of intermittent interruption of the oil supply which may occur during turns and acceleration and deceleration if it is intended to be used as not only a pre-oiler but a pressurized auxiliary sump.
What you use, if you use, a pre-oiler is a matter of individual choice and I’m sure there are any number of other factors to be considered but the above are the concerns I’m fighting with at this point.
DonC