Holley Ultra HP Carburetor atop an LS Engine

Best Of Both Worlds

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If you're a consistent reader of this magazine, then you've no doubt seen us extol the virtues of the LS family of engines ad infinitum. Our love affair with this amazing engine is based on science, and not just an infatuation with the "latest and greatest." After all, what's not to love about a lightweight aluminum engine that puts out so much performance per cubic inch? But there is a downside to this engine that many gearheads find daunting, and that's the computer and associated octopus of wiring required to get an EFI-fed LS engine in a car and running. Sure, thanks to the aftermarket it's easier today than it was, but many, especially those already well-versed in how to fiddle with a carburetor, prefer the simplicity of the older small-block Chevy engines. Well, it's possible to greatly simplify the addition of an LS engine to your Camaro by forgoing the EFI and feeding the LS with a carburetor.

Ls 2/24

To see what's involved and dyno-check the power potential of rolling old school with a carb, we followed along with a stroker LS3 build over at Don Lee Auto in Rancho Cucamonga, California. For this build, owner Tim Lee, wanted the benefits of LS power but preferred to not deal with trying to wire and tune an ECU.

01. Our starting point was this new Chevrolet Performance 376ci (6.2L for the metric crowd) aluminum block. Since displacement is power, we honed the bore out to 4.070-inches and decided to run a 4-inch-stroke crank, which will team up to give us 416 inches of glorious LS power.

Ls Engine 3/24

02. What stick you decide to stuff in the engine will ultimately determine its personality. Go super aggressive and you'll make more power, but it won't be happy cruising around town. We consulted with the cam gurus over at COMP and came up with a profile that should yield gobs of power and have nice enough manners for a Sunday cruise. The final specs on the XE-R cam were 238/240 with lift numbers of .605/.609 on a 112 LSA.

Comp Cam Xe 4/24

03. The heart of any stroker is the crank. For this build, we decided to try one from Eagle. This 4340 steel ESP LS crank came Magnafluxed, sonic-tested, and stress-relieved for longevity and improved bearing life, plus it won't break the bank in terms of cost. This 58x reluctor-equipped crank (PN 442740006100) set us back just over $800.

Eagle 4340 Steel Esp Ls 5/24

04. We also picked up a set of Eagle's connecting rods. The 6.125-inch billet 4340 steel H-beam rods (PN CRS612503D) came in a weight-matched set and priced just under $500. For pistons, we went with forged Mahle PowerPak flat tops (PN L92105070F04, $690). They came with a Grafal anti-friction coating on the skirts and are phosphate coated to reduce pin galling. The crank, rods, and pistons came in a balanced and ready-to-install kit from Eagle.

Eagle Connecting 6/24

05. After file-fitting and installing the rings, we slid the rod and piston assemblies into place and torqued them to spec. Made from 4032 low-expansion aluminum, these flat-top pistons should yield us an 11:1 compression ratio.

Mahle 7/24

06. Before the heads could go on, we needed to install the lifters along with the GM plastic lifter trays. We went with offerings from COMP (PN 850-16, $210) since they drop in just like the factory lifters and are easy on the wallet.

Comp 8/24

07. For heads, we went with these RHS cathedral port pieces (PN 54320-05TS). The 232cc heads came with 68cc combustion chambers, and their Clean Cast technology creates "as cast" ports that are comparable to ported heads. The fully assembled heads featured 2.055-inch intake and 1.600-inch exhaust valves.

Racing Head Service 9/24

08. To ensure a failure-free seal between the heads and the block, we installed a pair of Fel-Pro MLS head gaskets (PN 26192PT). We also ran a set of ARP Pro-Series head studs (PN 234-4317, $330).

Fel Pro Mls Head 10/24

09. We then turned our short block into a long one by installing the RHS heads and torquing them in place. We should note that by the time you read this these cathedral port LS heads will be discontinued by RHS. They have a new, higher flow, small-bore head coming out that's based on the LS7 design. We can't wait to check them out!

Racing Head Service Heads 11/24




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