Chevy High Performance - - Contents - TEXT & PHO­TOS: Jeff Smith

Twelve ideas that will make build­ing that next LS en­gine a plea­sure

Twelve ideas that will make build­ing that next LS en­gine a plea­sure

Now that the LS has bur­rowed deeply into just about ev­ery facet of Chevro­let per­for­mance, mak­ing power means spin­ning wrenches and swap­ping parts. That’s where the power the­ory runs right into spe­cific knowl­edge re­quire­ments. While the LS is con­sid­ered a branch of the small-block Chevy’s fac­tory tree, it’s at best a dis­tant cousin with its own, some­times quirky, set of de­mands.

We’ve been wrench­ing on LS en­gines long enough to have col­lected some work­ing knowl­edge that is worth pass­ing along. Some of these tech­ni­cal tid­bits you may have seen be­fore if you are an LS veteran, but re­mem­ber that not ev­ery­body has your depth of knowl­edge. We’ve also run across a cou­ple of new tools that will make your wrench­ing life eas­ier and less stress­ful. So with that said, walk out to the garage, open your tool drawer, and get wrench­ing on that new LS project.


If you’ve re­moved or re­placed the oil pump in your LS, or if the en­gine is brand-new, it can be chal­leng­ing to make oil pres­sure just by spin­ning the en­gine with the starter mo­tor. We learned a trick from George Rich­mond at Melling (the oil pump gu­rus) on how to pre-lube the oil pump, and it works on all LS en­gines. Re­move the oil passage plug at the front of the driver side of the en­gine block. This plug is large enough to al­low you to shove a 3/8-inch rub­ber hose into the hole. Then use a small fun­nel to pour a few ounces of en­gine oil di­rectly into this passage. This pre-fills and primes the oil pump.

Re­move that large 16mm plug from the front driver-side of the block and use a short length of 3/8-inch rub­ber hose and a fun­nel to pour a few ounces of en­gine oil into this passage. This will fill the oil pump cav­ity and prime the pump. This is usu­ally enough to al­low you to re­move all the spark plugs and spin the en­gine with the starter mo­tor and make oil pres­sure to lube the main and rod bear­ings be­fore start­ing the en­gine. If this does not work then you can re­sort to pres­sure lub­ing.


LS en­gines can be easy to work on. They can also be a pain. The plas­tic hy­draulic lifter hold­ers do a great job of hold­ing the lifters in place so you can change the cam. GM did this be­cause you have to re­move the heads to re­move or re­place the lifters. How­ever, prob­lems can sur­face with high-mileage en­gines with plas­tic lifter hold­ers that be­come brit­tle. The trick is to spin the cam around to push up the lifters (af­ter re­mov­ing the pushrods) and the hold­ers should do their job. But if one or two lifters slip out af­ter you re­moved the cam, you will hear that aw­ful clink when a lifter drops into the crank­case.

A very creative LS en­gine builder came up with the idea of slip­ping a length of 5/16-inch alu­minum dowel through each lifter bank. Some guys have used wooden dow­els, but we pre­fer alu­minum so there’s no dan­ger of the tool break­ing off when at­tempt­ing to re­move it. The dowel may al­low the lifter to drop slightly but it’s rel­a­tively easy to use a long tool to push them back up. The good news is the lifter won’t drop com­pletely out of the plas­tic holder. Pow­er­house sells this two-dowel set (PN POW101046) or you could eas­ily make your own. We’ve also seen steel rod used. Ei­ther way, ta­per the lead­ing edge of the tool so it’s eas­ier to in­stall and re­move.


Un­like its small-block cousin, the LS family of en­gines do not use dowel pins to lo­cate the front and rear cov­ers. GM rec­om­mends us­ing ridicu­lously ex­pen­sive ded­i­cated tools, but the af­ter­mar­ket has come up with a much sim­pler and less ex­pen­sive idea. Mr. Gas­ket re­cently re­leased sev­eral tools that make in­stalling both the front and rear cov­ers on Gen III and IV en­gines much eas­ier. They of­fer two dif­fer­ent front cover seal tools. The LSTC1 aligns the bare cover on the en­gine over the crank snout af­ter lightly po­si­tion­ing the bolts to hold the cover in place. Then, re­verse the tool to drive the new seal into place. The bolts can then be fully torqued. We found we had to also loosen the oil pan bolts slightly to make it all come to­gether.

The other front cover seal tool (LSTC2) is used to prop­erly po­si­tion the front cover over the crank snout if the seal is already in place.

The rear cover seal tool (LSRC1) po­si­tions the cover over the end of the crank­shaft, the bolts can be lightly tight­ened, and then the seal can be driven into the cover.

If you don’t build enough LS en­gines or per­form weekly cam swaps, then pur­chas­ing a front seal tool may seem like an ex­trav­a­gance. Be­fore Mr. Gas­ket in­tro­duced these tools, Kenny Dut­tweiler of Dut­tweiler Per­for­mance sug­gested that we build our own front cover align­ment tool. We dug up an old truck har­monic bal­ancer and used a cut­off wheel to re­move the crank hub from the bal­ancer. Then we used an abra­sive flap­per wheel to lightly hone the hub’s in­side di­am­e­ter un­til it would slide eas­ily over an LS crank snout. With a new seal in­stalled in the front cover, we placed the cover on the en­gine; lightly in­stalled all the cover bolts (in­clud­ing the lower pan bolts); and then slid our lubed, home­made hub into the front seal. Af­ter we made sure ev­ery­thing aligned prop­erly, we tight­ened the cover bolts and the two ver­ti­cal oil pan bolts.

One other trick is to place a small dol­lop of RTV at the cor­ners where the front and rear cov­ers con­tact the oil pan. This will pre­vent mi­nor oil leaks where the cover gas­kets meet the oil pan gas­ket.


Be care­ful—this could hap­pen to you! We ran into this while swap­ping heads on a 6.0L. We had in­stalled a set of ARP head studs in the en­gine in an­tic­i­pa­tion of su­per­charger boost. As we were ap­ply­ing the fi­nal torque se­quence on the head studs, some­thing felt as if it was giv­ing way—al­most as if the stud was stretch­ing since the torque, which nor­mally in­creases as we tight­ened the torque wrench, seemed to flat­ten out. That’s when we no­ticed the washer un­der the nut was turn­ing as we tight­ened the head stud nut. If you feel this, im­me­di­ately stop turn­ing the nut or head bolt.

ARP had told us about this a few weeks be­fore. It seems in the process of im­prov­ing the fin­ish on their wash­ers and bolts, the washer has be­come smooth enough that it no longer re­mains in place but be­gins to spin. This is most of­ten ex­pe­ri­enced on LS en­gines be­cause the spot fin­ish on the heads is very smooth, but ARP has seen this hap­pen on Ford Mod en­gines, es­pe­cially on the Coy­ote (not that you care!).

Here’s why this is a big prob­lem. Roughly 50 per­cent of the torque re­quired to cre­ate a clamp load on the head gas­ket is ab­sorbed by fric­tion be­tween the un­der­neath side of the bolt head and the washer—or in the case of a head stud, be­tween the nut and the washer.

An­other roughly 30 per­cent of the torque is ab­sorbed as fric­tion be­tween the threads and the block on a bolt or be­tween the threads and the nut with studs. This leaves ap­prox­i­mately 15-20 per­cent of the ap­plied torque that ac­tu­ally stretches the bolt. But if the head bolt washer turns, it es­sen­tially be­comes a bear­ing that dra­mat­i­cally re­duces the fric­tion, al­low­ing more torque to be ap­plied di­rectly to the bolt. This can quickly dam­age the bolt by stretch­ing it be­yond its yield point. If that hap­pens, the bolt is dam­aged and must be re­placed. The other pos­si­bil­ity is that the threads will pull out of the block. Ei­ther sit­u­a­tion is bad.

ARP showed us a sim­ple trick to avoid this prob­lem. Sim­ply sand the head side of the washer with 60-grit sand­pa­per, mak­ing about three passes across the washer. This cre­ates a rough enough sur­face so the washer does not move. Once all the wash­ers are sanded, be sure to clean them thor­oughly. It’s also im­por­tant to use ARP’s Ul­tra-Torque lu­bri­cant but only on the top­side of the washer. The head side of the washer should be as dry and clean as pos­si­ble for best re­sults. We have per­formed this trick sev­eral times and it works.


The Gen III and IV LS en­gines use two dif­fer­ent O-rings to seal the pickup to the oil pump. In the midst of swap­ping parts, it’s easy to get con­fused and use the wrong O-ring. The re­sult is the oil pump will be un­able to pull oil up from the sump. Zero oil pres­sure is the re­sult. That’s not a good place to be, but pick­ing the right O-ring is easy if you know where to look. Melling of­fers a chart that will dial you right in.

If the stock oil pump pickup has an O-ring groove in it or is ta­pered where it en­ters the oil pump, that de­sign uses the fac­tory red O-ring. This is re­placed with the Melling green O-ring. If the pickup tube is straight where it en­ters the pump and it uses the blue OEM O-ring, then use the Melling black O-ring. Both O-rings are supplied with each new Melling oil pump.


New or re­built en­gines should al­ways be pres­sure lubed be­fore you start them for the first time. The challenge with the LS is the oil pump is driven by the crank­shaft so that pre­cludes spin­ning the oil pump sep­a­rately. Sum­mit Rac­ing of­fers a 3-quart pres­sur­ized tank that can be filled with en­gine oil and con­nected with a braided line to the oil pres­sure port of an LS en­gine and then charged with pres­sur­ized air—usu­ally 50-60 psi.

If you’d rather build your own pres­sure pre-lu­ber, we built one us­ing a hard­ware store 2 1/2-gal­lon bucket, a small-block Chevy oil pump, hoses, fit­tings, and some scrap alu­minum plate. We mounted the oil pump to the in­side of the sealed lid us­ing 1/8-inch alu­minum plate as re­in­force­ment. We drilled and tapped the pump out­let for pipe thread to adapt a -6 male AN fit­ting and then cut the stock 5/8-inch pickup tube in the mid­dle and ex­tended it with a length of heater hose to the bot­tom of the bucket. We then used an Au­toMeter adapter fit­ting to at­tach the out­let from the oil pump to the LS oil sys­tem. You can use that same port men­tioned in the pre-lube tip. Fi­nally, we drilled and tapped a met­ric bolt that fits the drain plug hole to al­low oil to re­turn to the bucket.

We drove the oil pump with a 1/2-inch elec­tric drill mo­tor. The

re­turn line al­lows us to run the pump al­most con­stantly. The only is­sue we dis­cov­ered is we have to stop pump­ing oc­ca­sion­ally to al­low the oil to re­turn to the bucket. We’ve used both our home­made pres­sure pre­lu­ber and the Sum­mit tank sev­eral times on new and re­built LS en­gines and both work great.


Au­toMeter of­fers a nice kit that adapts stan­dard 1/8-inch NPT thread tem­per­a­ture or pres­sure gauges to the met­ric LS en­gines. The kit comes with two met­ric adapters; a low-pro­file tem­per­a­ture sender; and a 10K, 1/2-watt re­sis­tor. The first adapter is a 12x1.5mm to 1/8-inch pipe NPT

(PN 2277, sold sep­a­rately) to mount the wa­ter tem­per­a­ture send­ing unit. Be very care­ful when tight­en­ing this adapter, as it is very thin and will very eas­ily twist apart and fail—ask us how we know.

The se­cond fit­ting in the kit is a 16x1.5mm to 1/8-inch NPT fit­ting that re­places the fac­tory oil pres­sure send­ing unit for a me­chan­i­cal or elec­tri­cal pres­sure gauge fit­ting. Rather than pur­chase the en­tire kit, you can just buy the above wa­ter temp adapter and drill and tap into the oil pres­sure cover that sits just above the oil fil­ter on most LS en­gines.

This can be drilled and tapped for a stan­dard 1/8-inch pipe NPT fit­ting for a man­ual or elec­tric oil pres­sure gauge. The in­cluded re­sis­tor is of­ten re­quired to im­prove the tach sig­nal from the fac­tory ECU.


The of­fi­cial GM rec­om­men­da­tion for adding a new oil pump re­quires you to bolt the pump in place over the crank drive man­drel and then re­move the cover and place two 0.002-inch feeler gauges on op­po­site sides of the gear. Once the gear is cen­tered, the outer four bolts can be torqued and the cover in­stalled and torqued.

This procedure takes time and a bit of dex­ter­ity. Kenny Dut­tweiler showed us a short­cut that works and saves time. In­stall the oil pump over the drive and then gen­tly tighten the mount­ing bolts to the block. Now, spin the en­gine over gen­tly about four or five rev­o­lu­tions. The gears in the pump will align them­selves and then all you have to do is torque the pump in place.

The clas­sic line is “Trust but ver­ify.” That’s what we did, learn­ing that Dut­tweiler, of course, was right. The clear­ance was right at 0.002-inch all the way around the gears. So try this— and ver­ify it for your­self! It’s the lit­tle things like this that make as­sem­bling an LS a nearly plea­sur­able ex­pe­ri­ence.


When build­ing a new LS en­gine, it can of­ten be the small­est parts that cause the most grief. To make your life eas­ier, sev­eral com­pa­nies, in­clud­ing Sum­mit Rac­ing, have as­sem­bled the most in-de­mand parts so all you have to do is or­der one part num­ber as op­posed to five. The Sum­mit kit in­cludes the large coolant plug, the bar­bell, the small oil pres­sure passage plug, and three oil and wa­ter passage plugs.

This kit is de­signed for new blocks or used ones that have been com­pletely stripped for clean­ing. Each part is also avail­able sep­a­rately. The very large coolant drain plug re­quires a 17mm Allen wrench to re­move or in­stall. Amaz­ingly, our lo­cal hard­ware store had that ex­act wrench in stock. You will need this to in­stall that plug. As a last tid­bit, if you need LS block dowel-lo­cat­ing pins for the heads, you can make big-block Chevy pins work in a pinch.


When swap­ping heads on an LS en­gine, you might con­sider try­ing a slightly thin­ner head gas­ket. Stock LS MLS (multi-layer steel) gas­kets are gen­er­ally 0.053-inch thick, but Fel-Pro of­fers a se­ries of 0.041-inch gas­kets in dif­fer­ent bore sizes that will im­prove com­pres­sion slightly. For ex­am­ple, a 6.0L en­gine with a thin­ner 0.041inch thick gas­ket will in­crease the com­pres­sion ra­tio by 0.25—or from 9.5 to 9.75:1.

One ac­com­pa­ny­ing warn­ing is you must mea­sure pis­ton-to-head clear­ance. Pro­duc­tion LS en­gines of­ten protrude the pis­ton above the deck by 0.008-inch or more. This much pis­ton above the deck re­duces pis­ton-to-head clear­ance down to 0.033-inch with the 0.041-inch gas­ket. This should be suf­fi­cient for steel rod en­gines that don’t spin above 6,000 but it’s worth not­ing. The ac­cepted min­i­mum pis­ton-to-head clear­ance on most en­gines is 0.040-inch.

This isn’t go­ing to be worth a bunch of horse­power but ev­ery lit­tle bit helps. The part num­bers for the heads are listed in our ac­com­pa­ny­ing parts list. Also note that they are listed as left and right. Al­ways make sure they are in­stalled cor­rectly to en­sure proper coolant flow.


The stock LS val­ve­train is very ro­bust, but as valvespring loads in­crease this places greater pres­sure on the stock rocker trunnion and its tiny roller bear­ings. Sev­eral com­pa­nies,

in­clud­ing Sum­mit Rac­ing, of­fer trunnion up­grades. The con­ver­sion can be ac­com­plished with home­made tools, but the Sum­mit tool in­cludes a handy man­drel and mag­netic base that makes the job re­ally easy us­ing a sim­ple bench vise. We con­verted a set of 16 stock LS rock­ers in less than an hour us­ing the Sum­mit tool. We won’t run through the step-by-step, but af­ter you do the first cou­ple of rock­ers, it be­comes re­ally easy.


Among the LS en­gine’s idio­syn­cra­sies is the har­monic bal­ancer’s lack of threaded bolt holes, which of­fers no way to bolt on a nor­mal bal­ancer puller. Ken­tMoore of­fers spe­cial­ized tools that are nice and work well, but are also ex­pen­sive. We dis­cov­ered a slick, Posi-Lock three-jaw puller that works ex­cep­tion­ally well. It is over $100 but does an ad­mirable job. One ad­van­tage to this tool is that it can be re­pur­posed for many pulling tasks. Sum­mit also sells a set of tools that will both re­move and in­stall a stock har­monic bal­ancer. These tools are avail­able sep­a­rately or as a kit. Fi­nally, ICT Bil­let also of­fers a sim­ple threaded stud with a bear­ing that is very sim­ple and af­ford­able as an in­staller. CHP

There are some things about LS en­gines that make them easy to work on. And yes, other as­pects make them a bit frus­trat­ing. But once you learn the se­cret de­coder ring tips and tricks, it re­ally is a sweet­heart of an en­gine.

The Mr. Gas­ket front cover tool po­si­tions the bare cover over the crank snout to align it so the front seal can be driven in place. Make sure to add a drop of oil to the rub­ber O-ring in the tool.

Westech’s Steve Brule’ is in­sert­ing an LS lifter tool dur­ing a cam swap on the dyno. Ob­vi­ously, this long tool re­quires roughly 24 inches of clear­ance in front of the en­gine when at­tempt­ing a cam swap with the en­gine in the ve­hi­cle.

We made our own front seal align­ment tool us­ing the hub from a truck bal­ancer. Plac­ing this tool into the cover with the seal in place helps align the cover with the crank­shaft.

The Mr. Gas­ket rear seal cover tool aligns the rear cover over the crank flange. Then the seal can be in­stalled.

Us­ing the cor­rect O-ring will save you headaches later. If the wrong O-ring is used, the pickup may not seal prop­erly and the pump will not be able to cre­ate pres­sure.

We sanded all the head bolt or head stud wash­ers with 60-grit on the washer’s head side to avoid prob­lems. When torque­ing the head bolts, mon­i­tor the washer care­fully. If it spins, this can quickly put ex­ces­sive load into the fas­tener and dam­age it or the block.

The bar­bell must be in­stalled in this man­ner, with the O-ring fac­ing out­ward.

Slip the oil pump over the crank snout, and with lightly tight­ened bolts, turn the crank roughly four or five rev­o­lu­tions. Then torque the oil pump bolts and the pump will be aligned. GM’s torque spec for the pump is 18 ft-lb. The pump cover bolts are 106 in-lb.

The Sum­mit kit will work for any Gen III or IV block. The Gen Vs re­quire dif­fer­ent fit­tings.

The Au­toMeter kit in­cludes both an adapter to mount a wa­ter tem­per­a­ture sender in the fac­tory hole and an oil pres­sure gauge. Be care­ful when tight­en­ing the coolant fit­ting as it can eas­ily shear as the con­nec­tion is ex­tremely thin.

Head gas­kets aren’t nearly as ro­man­tic as camshafts or cylin­der heads, but small changes like a thin­ner head gas­ket will con­trib­ute in a small way to both in­crease power and im­prove ef­fi­ciency.

Sum­mit of­fers the trunnion con­ver­sion kit that in­cludes 32 bear­ing halves, 16 forged steel trun­nions, and 32 beefy C-clips.

The Posi-Lock puller works very well. We placed a small, 1/8-inch thick steel plate in front of the crank­shaft to give the cen­ter post a nice, flat sur­face. The three jaws hook into the in­te­grated flat sur­faces on the back­side of the bal­ancer.

The Sum­mit tool kit of­fers the abil­ity to pull and in­stall fac­tory LS bal­ancers. The press-on in­staller is in the fore­ground while the puller uses dif­fer­ent length pins that fit in­side the crank snout to push on the crank to re­move the bal­ancer.

Here, we’re press­ing in the se­cond of the two bear­ing halves. Press them in just enough to al­low the clips to fit in the shaft. This al­lows the shaft to move freely. In­stall the clips and the job is done.

The con­ver­sion tool uses the large base (1) along with the re­ceiver for the op­po­site side (2), a man­drel (3), wash­ers (4 and 5), and an align­ment pin (6).

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