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
Smart Recycling
Like most environmentally conscious shops, our shop is into recycling. We recycle all metals. One of the time consuming things we do is removing rings from pistons so the shop can get a better price for the scrap aluminum.
All our machine shop personnel and the techs in our R&R shop wear latex gloves all the time. When it is time to strip rings from pistons we put on brown cotton jersey gloves over the latex. We used to do the stripping without the cotton gloves but the latex gloves wear and a lot of us got cuts on our fingers and hands.
With the cotton gloves you only have to rotate your hand around the head of the piston and the cotton glove grabs the ring and does the work for you. It doesn’t matter whether it is the top ring or the scrapers on the oil ring. The sharp edge of the ring hooks right onto the glove and comes off. No cuts or gashes and you are done in no time.
Dom Rinaldi, Sr.
Rinaldi Engine Center
Skowhegan, ME
Modular Ford Valve Cover Removal
Ford’s 4.6L and 5.4L modular valve cover bolts often rust and/or strip. I have found that the easiest way to remove them is to use an 8 mm socket, an extension and a short breaker bar. Tap the top end of the breaker bar with a brass hammer while turning. This will shake the bolt loose 99.9% of the time.
Arus Kinney
Austin Jordan Engines
Wyoming, WI
Manufacturer Shop Solution: Don’t Be Afraid To Increase The Ring Gap
Current ring materials and more precision cut ring grooves are causing higher rates of ring expansion so don’t be afraid to increase the ring end gap. Butting rings are a major factor in lifted ring lands and eventual piston failure. Slightly larger end gaps have little effect on leakdown numbers, and yet will improve durability and ring life.
Power adders certainly create more horsepower and resulting heat is passed to the ring requiring even more gap. Different ring materials can also be used to improve ring seal and life.
When in doubt, call the manufacturer for recommendations regarding your specific applications. Specifications supplied with pistons are fairly general and technical advisers are there to help you get the most performance and reliability possible from your specific combination for free.
Randy Gillis
Technical Sales
JE Pistons
Huntington Beach, CA
Engine Builder Shop Solutions is sponsored by Engine Pro,
a consortium of 9 engine parts specialist WDs operating 30 branch
locations serving engine builders/rebuilders across the U.S. Shop
Solutions published in each issue of Engine Builder Magazine are
awarded a $100 Visa Gift Card. Winners will be chosen by
the staff of Engine Builder Magazine and the Engine Pro Technical
Committee.
To submit a Shop Solution simply mail your entry
to Engine Builder Magazine, Shop Solutions, 3550 Embassy Parkway,
Akron, OH 44333; or email to Shop [email protected]. Shop
Solutions may also be emailed to [email protected].
You must include
your name, shop name, shop address and shop telephone number. Submitted
Shop Solutions not published will be kept on file and reevaluated for
publication with each month’s new entries. If you include your email
address you will be emailed notification of publication if your Shop
Solution is chosen.
