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For those considering building an LS engine for the first time, this newer generation small block presents some oiling system elements that demand attention. Much like its predecessor small-block Chevy, the LS engine offers its own unique oil galley configurations. Those familiar with the LS know that the oil pump is driven directly off the crankshaft at the front of the engine. The pump inlet is fed with a long pickup tube originating in the oil pan sump.
The main oil galley runs from the pump down the driver side of the block and there are two access plugs, one on each end of the block. With the front cover removed, a press-in plug is used to seal that end of the main oil galley. These plugs are removed when the engine is disassembled for a rebuild but must be reinstalled. If omitted, this will create a massive internal oil leak and the engine won’t make oil pressure.
There’s another plug located on the passenger side of the block, at the rear. It’s accessed with the rear cover removed. This plug is most often described as the “dog bone” or “barbell” because of its shape. Some confusion has occurred over how this plug should be installed, because it can be inserted two different ways. But there is only one correct procedure. The oil seal should always be toward the outside of the block, with the serrated portion of the dumbbell toward the inside. This should follow common sense, since the O-ring seal is what prevents leaks outside the oil galley.
Removing the barbell can be a hassle. We’ve found that drilling a tiny, shallow hole in the center of the original barbell and then inserting a small machine screw into the hole will offer sufficient grip to remove the plug. This also prevents scratching the inside diameter of the seal bore, which could cause issues with leaks.
There are also questions about aftermarket billet-aluminum versions of the barbell. Some aftermarket barbells do come drilled and tapped for a bolt that can facilitate removal, which offers an advantage over the plastic OE version. But frankly, while these products are nice, they’re also more than double the price with perhaps a minimal effect on lubrication system performance.
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The oil gallery plug must be installed in the front of the oil galley on the driver side. If this plug is omitted, there’s no chance for the engine to make oil pressure.
Installing the barbell properly places the O-ring toward the outer end where it seals oil pressure in the block.
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