Sure, we could have bolted in a much longer duration cam and perhaps pumped up the peak horsepower and called ourselves heroes. Cam fans may have already noticed that we didn't really make that much of a change-the 290hp crate engine's intake duration is only 2 degrees less-222 degrees at 0.050 versus 224 degrees for the XE cam. But now we yanked the intake, harmonic balancer, and front cover then removed the old cam in favor of a COMP Cams Xtreme Energy 268. Up until now this had been an external bolt-on affair. Now we were ready to tear into the engine. This dish is a full round dish so there's very little quench, which tends to diminish combustion efficiency slightly, but short of changing pistons (which defeats the main purpose of a crate engine) this is what we'll work with. The pistons have four valve reliefs and (while we didn't measure it) the dish specs at 10 cc.
Chevy claims this is an 8.0:1 compression engine and our calculation was pretty close at 8.1:1. These rotators help prevent exhaust valve seat erosion under hard use, but also add weight so they're not the best idea for a performance engine. The iron heads are 76cc combustion chamber units with 1.94/1.50-inch valves and exhaust rotators on the exhaust valves. This engine is one step above the basic replacement engine and is designed to run on 87-octane fuel. The engine employs the classic two-piece rear main seal iron block with iron heads, 8:1 compression ratio, a mild flat-tappet hydraulic camshaft, cast aluminum pistons, and a cast crank. This is what Chevrolet Performance calls the 350/290, which stands for 350 ci and 290 hp. And sing it does.īut before we get to the fun stuff, let's quickly hit the specs for our Great Crate. We have a moral obligation to tweak this crate engine to see if we can make it sing. But this is STREET RODDER, which means we can't leave it stock. But for the street set, simple crate engines have become the quickest and easiest path to movin' down the highway. Chevy builds those too and that LS-based 770hp LSX454R is just one example of what's going on in that arena. While some guys will always insist on building their own engine, for the rest Chevrolet Performance has done an outstanding job of offering a package that is affordable and can make decent power-with a little bit of help. The real reason is that there are just so blasted many little-block engines roaming the earth we can't ignore them. It's not because we aren't creative enough to come up with something better. The third is you can rely on car magazines to do small-block Chevy engine stories. The clich holds there are only two things that you can count on, death and taxes.
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