How to Build an LS79 Engine - A Modern Classic

We take a classic displacement combo and modernize it with LS technology

Patrick Hill Mar 28, 2014 0 Comment(s)
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In the midst of a brainstorming session with AntiVenom Performance’s Greg Lovell, we started talking about LS engine builds and how everything seems to be the same, with the most common two being a 408-inch build or a 346-inch combo. Yes, there are 427s, LSX 454s, RHS-based motors, etc, but they aren’t as common as the 408 or 346.

Looking at the available displacements and combos of factory LS motors, we started comparing that to the combos you can build on the Gen I platform. At some point, we started talking about the 327 and how it was the top dog for a long time. Even after the 350 assumed king of the mountain status, the 327—with its short stroke and large bore combo (3.25 stroke by 4.00-inch bore)—was widely popular. It would rev to the moon, but the big bore allowed it to swallow a lot of air.

We compared that to the closest modern equivalent, the 5.3L Gen III truck motor. The 5.3 uses a 3.78-inch bore, combined with a 3.62 stroke, for a displacement of 325 inches. It’s a strong performer in its own right, but more on the torque side for its truck application. Then we started thinking about its little brother, the 4.8. It uses the same bore, but with a shorter 3.27 stroke, just a smidge longer than the original 327. That led us to consider the larger 6.0L truck engine and its 4.00-inch bore.

With the wheels inside our brains really spinning, it hit us: What would we have if we combined the 6.0L block with the 4.8 crank? A 4.00-inch bore combined with a 3.27 stroke crank would give us a displacement of 329 ci. We’d essentially have a duplicate of the old 327, but with all the modern design and capability of the LS platform, using off-the-shelf parts!

We know, a lot of people are thinking we’re crazy here. Why build smaller instead of larger? Well, the simple reason is, insatiable curiosity. We wanted to see what the power would be like from a classic bore/stroke combo, using the superior airflow of an LS head.

After hitting the parts catalogs for several companies, we put together our shopping list and started getting everything together. This story will focus on the parts going into our recipe, and putting it all together. Stay tuned to a future issue of Super Chevy, where we’ll be bolting this bad boy to the engine dyno and seeing how much power it can make. Everything we used is listed in the parts list below, along with the corresponding prices through Summit Racing, or the specific manufacturer if not carried by Summit.

Truck Engine Block 12140 2/41

01. The starting point of our build was a 6.0L truck block, PN 12140 from Summit Racing. It comes fully cleaned, machined with a 0.030-inch overbore, and prepped for use with cam bearings and main caps installed. The 4.030-inch bore will give us a displacement of 334 ci, only 3 inches more than a Gen I 327 with a similar overbore.

Ls Engine Main Cap 3/41

02. One of the strengths of the LS series engines are the six-bolt, cross-bolted main caps. These give the bottom end enormous strength, even in high-horsepower applications.

Ls Engine Crank Thrust 4/41

03. Another aspect that gives the LS strength and durability is the location of the crank thrust, here at the center main bearing. On Gen I engines, the thrust is located off the rear most bearing. This means less wear and tear on the crank and its bearings.

Clevite H Series Bearings 5/41

04. For our main bearings, we went with Clevite’s H-series coated bearings. Developed primarily for the brutal rigors of NASCAR racing, Clevite’s Tri-Armor coating offers excellent lubricity and reduced friction, while adding protection against engine damage in a low oil pressure situation. For the rods, we went with Sealed Power’s Duroshield Competition Series bearings. The coating’s hydrophilic matrix actually bonds with the bearing material, absorbing oil for reduced friction and better lubricity.

O Reilly Crankshaft 6/41

05. Our crankshaft is a reconditioned, factory 4.8L, 3.27 stroke crank we picked up from O’Reilly Auto Parts. It came with a 0.010-inch undercut on the main and rod journals, so we ordered our bearings accordingly.

Main Cap Bolts 7/41

06 To further strengthen our bottom end for current and future testing, we pitched the stock main cap bolts for a set of ARP high-strength main studs. Main studs not only provide more main stability by preventing them from “walking,” but they also exert less stress on the block threads, which helps to extend block life—especially on aluminum blocks.

Arp Main Studs 8/41

07. You also get a more accurate torque reading off of a stud than a bolt, which can affect bearing clearances in some cases.

Wiseco 2618 Alloy Slug Piston 9/41

08. For pistons, we went to Wiseco for a set of forged 2618 aluminum alloy slugs. They feature a similar to stock but a bit heigher pin height, Wiseco ArmorGlide skirt coating for reduced friction and wear, and offset wristpins for cold-start noise reduction. Wiseco also cuts them with LS multifit valve reliefs, compatible with cathedral port and square port cylinder heads. A nitride steel top and Napier second ring package allow for the best sealing, power, durability, and reduced oil consumption. The ring land thickness is maximized to withstand high levels of boost and nitrous. We went with a compression height of 11.0:1, the same as an LS7.

Ring Gaps 10/41

09. Greg Lovell, owner/operator of AntiVenom Performance in Seffner, Florida, assembled our engine. He set the ring gaps at 26 top and 28 middle, giving us the option of applying nitrous to our LS79 later down the road.

K1 Technologies H Beam Rods 11/41

10. For rods, we went with K1 Technologies forged billet H-Beam rods in a 6.390-inch length.

K1 H Beam Rod Height 12/41

11. Why such a long rod? Combined with the heigher pin height of our pistons, this will not only give us an excellent rod/stroke angle but an enormous amount of dwell at top dead center, which means we’ll be able to maximize the amount of time the combustion process has to take place, along with transferring the most energy from the piston to the rod on the down stroke.

Arp Head Studs 13/41

12. Up top, we went with ARP head studs for the same reasons we went with studs on the main caps. Besides offering superior clamping power and sealing, going with head studs will make any future head changes we think of a snap, and also put less wear on the block threads.

Comp Cams Hydraulic Roller 14/41

13. For the cam, we went to the valvetrain experts at Comp Cams for a custom-ground hydraulic roller similar to an LS9 cam. Our cam has a 122.5-degree lobe-separation angle with lift of 0.557 intake/0.572 exhaust, duration at 0.050 of 212/230, ground on a three-bolt LS1 cam core with the rear reluctor so we could use the rear-mounted cam sensor on the 6.0L block.

Cam Nose Bolt 15/41

14. Early LS engines used a three-bolt cam nose to retain the cam sprocket, similar to the Gen I engines. Later, GM went to a single-bolt configuration on some applications.

Cam Retainer Plate 12589016 16/41

15. LS motors use this cam retainer plate to keep the cam from walking in the block. We ordered a factory GM plate for our build, PN 12589016.

Ls Valley Cover Summit 12577927 17/41

16. The only source for an LS valley cover is either the junkyard or Chevrolet Performance. We ordered a new one through Summit, PN 12577927.

Chevrolet Roller Lifters 18/41

17. We also ordered from Chevrolet Performance a set of factory roller lifters (PN 12499225) and lifter guides, PN 12551162 (sold as a set of four). When buying a bare LS block, there are certain factory-only components you’ll need to get, like we did. Page 258 of the 2013 Chevrolet Performance catalog lists all the part numbers necessary for this under “Block Completion Components” so you won’t miss anything.

Lifter 19/41

18. The lifter guides not only keep the lifters from rotating while the engine is running, but they also hold up the lifters for easy camshaft removal without having to take off the heads and remove the lifters.

Arp Valley Cover Bolts 134 8002 20/41

19. We hit up the ARP catalog for all the best fasteners for our LS79, including a set of valley cover bolts, PN 134-8002.

Comp Cams Adjustable Timing Set Chain 3158kt 21/41

20. For the timing chain, we went with Comp’s adjustable timing set, PN 3158KT.

Arp Bolts Studs 22/41

21. Like we said before, we hit up the ARP catalog for just about all the fasteners to build our LS79. ARP has an extensive line of bolts and studs for LS engines in both stainless and black-oxide finish.

Melling Oil Pump 10296 23/41

22. To supply our motor with plenty of oil, we got a Melling high-volume oil pump, PN 10296, that features a CNC-machined body and hardened steel gears.

Chevrolet Performance Front Cover 12561243 24/41

23. For the front cover, we went with the early-style (no cam sensor) from Chevrolet Performance, PN 12561243. To install the cover properly, you need a special alignment tool (seen in photo). If you just try to guess at it, you’ll probably end up with the crank seal leaking.

Chevrolet Performance Rear Cover 12639250 25/41

24. The rear cover is also a Chevrolet Performance–only unit, PN 12639250, but it’s available for ordering through Summit Racing, just like the rest of the Chevrolet Performance parts used in this build.

Mast Motorsports Ls Conversion Pan 401 111 Top 26/41

25 & 26. For an oil pan that would be compatible with whatever classic Chevy we decide to install the LS79 in, we went to Mast Motorsports for its LS conversion pan, PN 401-111.

Mast Motorsports Ls Conversion Pan 401 111 Bottom 27/41

26.

Cosmetic Upper Lower Gasket Kit 28/41

27. For sealing our engine, we went with Cometic’s upper and lower LS gasket kits, PN PRO1025T and PRO1007B. You need to order both kits, as the lower kit comes with the oil pan, front cover, and rear cover gaskets, along with some other small items necessary.

Costmetic Upper Gasket Kit 29/41

28. Our Cometic upper kit features Cometic’s MLS (Multi Layer Steel) head gaskets. MLS gaskets not only provide superior sealing, heat resistance, and durability, but they can also be reused several times, unlike conventional head gaskets.

Trick Flow Heads Genx 30/41

29. For heads, we went with Trick Flow’s GenX 255 LS3–style head, PN TFS 32610001-c01.

Trick Flow Heads Genx Ported Runners 31/41

30. They feature fully CNC Competition Ported runners with a 12-degree angle on the valves for increased piston-to-valve clearance, redesigned coolant holes on the deck to work with all LS head gaskets, and LS3-style intake ports that will accept LS3 intakes and LSA/LS9 blower assemblies.

Trick Flow Heads Genx Valves 32/41

31. They come equipped with dual valvesprings, steel retainers, and 2.165/1.600 size valves.

Tfs Dual Springs 33/41

32. The TFS dual springs have a maximum lift of .625”, and while they are perfectly capable, with went with a set of dual springs and tool steel retainers from Comp Cams, part no. 26925-16. They have a rate of 400 pounds, maximum lift of .660”, seat load of 141 @ 1.810” and open load of 405 @ 1.150”.

Comp Cams Pushrods 7750 16 34/41

33. For pushrods we went with 7.750 length, heavy wall one-piece pushrods from Comp Cams, part no. 7750-16.

Comp Cams Roller Trunnion 35/41

34. We went with a set of stock LS3 rockers, but ordered one of Comp Cams roller trunnion upgrade kits for them. On the left is the stock trunnion; on the right is the Comp unit. The factory trunnion doesn’t feature a full trunnion, and the needle bearing retention system is weak and known to eject bearings into the oil under heavy use and abuse. The Comp upgraded trunnion uses a fully captured needle bearing assembly, along with a full trunnion shaft that not only reduces friction, but will also take more horsepower and abuse.

Dual Plane Carbureted Intake Manifold Chevrolet 36/41

35. On the dyno, we’re going to test out two different carbureted intake manifolds. This dual-plane unit is from Chevrolet Performance, PN 19244037. It’s a dual-plane design for increased bottom end and midrange torque with injector/nitrous bosses cast into it and a 4150-style carb-mounting flange. It also uses the factory O-ring gaskets and intake bolts.

Mast Motorsports Carbureted Intake Manifold 37/41

36, 37, 38. Our other test intake is this artwork-like piece from Mast Motorsports. It features fully CNC’d ports and runners that are hand blended with long, straight shot runners right to the valves for maximum high-rpm performance.

Mast Motorsports Carbureted Intake Manifold Runners 38/41

37.

Mast Motorsports Carbureted Intake Manifold Ports 39/41

38.

Holley 750 Cfm Ultra Double Pumper Carb 40/41

39. For our carb, we went with the old reliable, Holley's 750 CFM Ultra Double pumper with electric choke. It features billet metering blocks, and built in sight windows for easy float adjustments. or our carb, we went with the old reliable, a Holley 4150 double-pumper 750 cfm.

Ati Damper 41/41

40. And to keep everything balanced while driving out the water pump, we used an ATI damper, PN 917286. And with that, we’re all set and ready to hit the dyno. Stay tuned to a future issue of Super Chevy to see our full story on dyno testing this animal and to see if it lives up to its small-block heritage and LS79 name.

PARTPART NUMBER
0.030 inches over 6.0L block SUM-150105
Reconditioned 4.8L crank 12140
Trick Flow Heads TFS 32610001-c01
Wiseco Pistons Custom Via Summit
K1 Rods CH6390ALLBLS-ST8-A
Comp Cams custom ground camshaft 54-000-11
Comp rocker arm trunnion upgrade Kit 13702-KIT
Timing Set 3158KT
Factory roller lifters 12499225
GM valley cover 12577927
GM timing cover 12561243
GM rear cover 12639250
GM cam retainer plate 12589016
GM timing chain damper 12588670
GM head locating dowels 12570326
GM lifter guide 12551162
Melling oil pump 10296
ATI balancer 917286
Chevrolet Performance intake 19244037
Mast Motorsports intake 501-001
Mast oil pan 401-111
ARP head studs 234-4317
ARP main studs 234-5608
ARP balancer kit 234-2503
ARP valve cover 400-7530
ARP oil pan 434-6902
ARP timing cover 434-1502
ARP water pump 434-3202
ARP intake valley cover 134-8002
ARP intake manifold 130-2101
ARP thermostat housing 434-7401
ARP coil bolts 134-2301
ARP cam bolts 134-1002
ARP cam bolts 134-1003
ARP header bolts 400-1211
ARP rear cover 134-1504
ARP valve cover 400-7529
Clevite-coated H-Series 0.010-inch main bearings MS2199HK10
Sealed Power Duroshield Competition 0.010-inch rod bearings C8-7100CH10
Cometic upper gasket set PRO1025T
Cometic lower gasket set PRO1007B

Sources

Wiseco Performance Products
Mentor, OH 44060
440-951-6600
www.wiseco.com
Trick Flow Specialties
Tallmadge, OH 44278
330-630-1555
www.trickflow.com
Comp Cams
Memphis, TN 38118
800-999-0853
http://www.compcams.com
Summit Racing
Akron, OH
800-230-3030
SummitRacing.com
Driven Racing Oil
Huntsville, NC
866-611-1820
drivenracingoil.com
AntiVenom
Seffner, FL 33584
813-381-3995
www.antivenomefi.com
Mast Motorsports
Nagodoches, TX 75964
866-551-4916
http://www.mastmotorsports.com
K1 Technologies
Byron Center, MI 49315
616-583-9700
www.k1technologies.com
Holley Performance Products
Bowling Green, KY 42101
270-781-9741
http://www.holley.com
ATI Racing
Baltimore, MD 21207
1-877-298-5039
www.atiracing.com
Chevrolet Performance
800-450-4150
http://www.chevroletperformance.com
MSD Performance
El Paso, TX 79936
915-857-5200
http://www.msdignition.com/
ARP
800-826-3045
ARP-BOLTS.COM
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