Originally Posted by cobalt327
The holes feed the cam bearings then the top end.
Not on a Olds motor they don't. As the OP noted, a quick look at the factory service manual shows that the Olds oiling system feeds the lifters off the main galleries FIRST (which also feeds the top end), then the mains, and the cam bearings last. Putting the restrictors in the cam bearing feed holes only restricts oil to the cam bearings, nothing else. To restrict oil to the top end, you need to insert restrictors in each of the 16 lifter feed holes off the main galleries. The cam bearing restrictors are worthless but Mondello sells a lot of them based on misinfromation and the fact that they are easy to install.