Need input! Block back from machine shop. LOTS OF PICS!

The chain is oiled by splash. In soem years, a top bolt is left ou. in others, a hollow bolt is installed. Usually its the pass side hole regardless. The valley fills with oil draining back from the ehads, and it spills out the hole and either onto a small wedge shaped metal tab, or the windage from the chain whips it all over. Some builders like to use a very small hole to pressure feed the chain. IMO, this is way over kill, and it tends to reduce the volume available for the lifters. If the lifter bores are a little worn, any loss can make hydraulic lifters noisey or not work quite right. It's just not needed.