Thought this might be helpful for guys swapping/mod'ing a LS.It is a article from Engine builder:

GM LS Engine Building Tips
The GM “LS” engine format (GEN III and IV) is a replacement for the Chevy small block. For performance purposes it is no problem to obtain 500+ horsepower from just about any version of this engine. The following are some tips and suggestions we have found to make working on these engines easier and to turn out a better product:

• All OEM fasteners are metric

• All LS engines have roller camshafts

• The roller lifters are grouped into batches of four, guided by a plastic lifter bucket for easy installation and removal.

• When the stroke is increased, the #8 piston skirt may come into contact with the reluctor wheel, requiring the use of readily available aftermarket side relief pistons.

• The oil pump is front-mounted and crankshaft-driven.

• The water pump is unique to the LS engine.

• All LS engines have a different firing order than the earlier small block engines. Due to this change in firing order, LS camshafts are unique to the LS family. LS firing order: 1-8-7-2-6-5-4-3; SBC firing order: 1-8-4-3-6-5-7-2.

• OEM main caps are powdered metal, but they differ from the connecting rods in that they are not a “cracked” fit as are the connecting rods. They are machined flat and register tightly into the block and can be re-machined and re-bored just like a normal cap. Steel aftermarket caps are available for these blocks. Each main cap is secured with four primary vertical bolts and two side bolts. When fitting the crankshaft, don’t attempt to rotate the crankshaft until all cap bolts have been tightened to specifications, since the main bores will likely not provide proper alignment until all caps are fully tightened.

• LS engines feature a “toothed” reluctor wheel that is pressed fit onto the rear of the crankshaft and is used for ignition timing. If you need to replace or install a reluctor wheel, note that it is an interference press fit with no key or registering device. Be advised that the clocking position is critical for proper timing reference. Goodson Shop Supplies offers as very handy installation and indexing tool for this job (#RRJ-350 Reluctor Ring Jig). The reluctor wheel must be heated to 450° F and then placed onto the crankshaft using the tool to index it to the correct position. This is fairly easy, but you need the tool to do it right.

• Connecting rods are “cracked” fit powdered metal and cannot be reconditioned if more than .002˝ out-of-round.

• When changing the camshaft in an already-assembled LS engine, there is no need to remove the lifters. With the rockers loose and pushrods removed, rotate the cam 360 degrees. This will push the lifters up into the lifter buckets, out of the way of the cam. To ensure that none of the lifters accidentally drop down, we always carefully insert a 22˝ or longer 1/4˝-diameter rod into each of the lifter galley oil channels. Once the camshaft is in place, remove the metal rods. Using your finger, press each pushrod down against the lifters to dislodge them from the buckets.

Jim Kovach
Kovach & Associates
Performance Engine Building
Parma, OH

 

{moved to the LTX and LSX Engine Swap subforum}

Most LSx guys will be familiar with these details, but for someone new or interested in learning more, it's good information.

Although this is a bit confusing:
I would have said, "The roller lifters are guided by a plastic lifter bucket, each bucket holding 4 lifters." I suspect the design has as much to do with ease of mass production as anything else. The aftermarket has metal replacements for better reliability (although they don't aide the easy cam swapping of the factory stuff).

 

when new, the plastic buckets are a great idea that aid in easier cam swaps, it seems like they can wear out on the higher mile motors and end up not holding the lifters like they should. many of the cam swap threads i've seen over at 'tech recommend either using pen magnets to keep the lifters up or using dowels from the front for a bit of extra protection