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The Jp Chevy 350 Part 2

Posted in How To: Engine on March 1, 2010 Comment (0)
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In December we outlined an engine recipe for a Chevy 350 that you could duplicateusing mostly junkyard parts that we theorized should have made about 400hp/ 400lb-ft. In reality, we were secretly thinking we'd make about 390-395hp and a little better than 400lb-ft. Well, as you can see from the dyno graphs, we didn't quite hit the mark. Regardless, this kind of power from simple, bolt-on parts thrown at a stock-type Chevy 350 short block isn't too shabby.

The GM Performance 290hp 350 crate engine we used proved itself as durable as an anvil. We mercilessly beat it with almost two hundred full-throttle, full-load dyno pulls up to 6,500rpm, and a couple up to nearly 7,000rpm. And it held. As for our camshaft selection, we'll admit that the Lunati Voodoo 268 grind is a bit gnarly for our cylinder heads. Even with our Lunati PN 74818 springs set up to deliver a burly 155lbs-seat and 330lbs-open spring pressures, we still ran into some valvetrain harmonic issues between 5,300 and 6,000rpm. This caused a dip in the power levels right where our peak horsepower would've been found. Ideally, if we were to do this over again, we'd probably select a Voodoo cam with a shorter 219/227 duration @ 0.050 and .468/.489-inch lift (PN 60102), or even one of Lunati's new Street/Strip cams with a less-aggressive lobe profile offering 223/231 duration @ 0.050 and .463/.485 lift (PN 301A9LUN). Either probably wouldn't cost us much (if any) top end power, and would serve to fatten up the torque curve a bit.

In the end are we unhappy? Well, yeah. Even though we upped our crate engine by 72hp and 57lb-ft, and even though you can technically duplicate this engine for just over $1,200, we really wanted to reach that magic 400hp/400lb-ft mark. Regardless, we wound up with more power than most crate engines out there at roughly half the price. So for what it's worth, here's the result of a couple days' worth of spinning wrenches and pistons on the Westech Performance dyno, dozens of gallons of Rockett-brand racing fuel, and a good amount of stomach lining.

We used E3 spark plugs for all our dyno testing. The company's unique DiamondFire electrode creates a mushroom cloud of spark for repeatable performance on the dyno. And if you're trying to squeak a gross-polluter through a smog check, the company's testing has shown the plugs actually reduce emissions as well. We used 100-octane Rockett Brand fuel on the dyno, but our combo will easily run on 91- or even 89-octane pump gas.
View Slideshow

Parts List
Want to duplicate our combo? Even though we used a solid and dependable 290hp 350 crate engine and brand-new Vortec heads from GM Performance Parts as our base for this buildup, you could theoretically substitute a decent $100 junkyard 350 shortblock from any '70s-'90s GM car or truck, a set of $180 Vortec heads from the boneyard, and use cheap stock valve covers and fasteners where applicable to duplicate this combo for less than $1,250. Prices were found online as of press time through Pace Performance or Summit Racing. Items marked with an asterisk are optional, meaning stock parts can be substituted.

GM Performance Parts
PN 12558060 Vortec head assembly $579.90
PN 12495491 Heavy-Duty pushrods (16) *$42.95
PN 12499223 Gasket set $96.95
PN 12495499 Head bolt set $28.95
PN 25534359 Circle track valve covers *$114.95
PN 25534355 Valve cover breathers *$38.95
PN 12338092 Valve cover bolts (8) $15.60
PN 12550027 Intake bolts (8) $23.04
PN 12495490 1.5:1 self-aligning rocker arm kit $56.95
Fel Pro
PN FEL1094 0.015-inch compressed head shims (2) $43.76
Lunati
PN 60103LK Voodoo 268 cam &lifter set $185.95
PN 93117 Double roller timing chain $43.10
PN 74818LUN Beehive ovate springs (16) $167.58
PN 75787LUN 7-degree spring retainers (16) $55.01
PN 85340LUN 1.5:1 self-aligning roller rocker arm kit $338.10
Professional Products
PN PP52033 Hurricane Vortec manifold $172.99
Weiand
PN 8502 Air Strike Vortec manifold $217.88
TOTAL With stamped steel rockers $1666.63
With roller rockers $1947.78

Engine Test 1 Test 2 Test 3 Test 4
Speed (rpm) Hp Tq Hp Tq Hp Tq Hp Tq
3000 169 297 211 369 208 365 208 367
3200 190 312 223 365 220 361 220 361
3400 209 323 248 383 245 379 242 374
3600 229 334 269 393 269 393 262 383
3800 244 338 288 398 287 397 281 389
4000 259 341 304 399 306 402 301 395
4200 271 339 317 396 321 401 319 398
4400 283 338 332 397 335 399 332 397
4600 294 336 346 395 348 398 346 395
4800 302 331 356 389 358 392 359 393
5000 309 326 364 383 367 385 371 389
5200 314 317 373 376 379 381 381 384
5400 314 306 375 364 378 367 385 374
5600 313 293 371 348 376 353 386 362
5800 313 284 364 330 374 338 383 345
6000 310 278 364 319 377 330 383 336
6200 - - 363 308 375 318 381 323
6400 - - 356 292 367 303 375 308

Test 1: Baseline GMPP 290hp 350 crate engine, GMPP 222/222@0.050, .450/.460 lift camshaft, Weiand Action Plus manifold, Holley 4779 double-pumper carb, 34 degrees ignition timing, 13/4-inch long-tube headers

Test 2: Lunati Voodoo 227/233 @ 0.050, .489/.504 camshaft, Weiand Air Strike Vortec intake, 1/2-inch phenolic carb spacer, Holley 4779 Double Pumper carb, 36 degrees ignition timing, 13/4-inch long-tube headers

Test 3: Same as Test 2 but with Lunati 1.5:1 roller rockers

Test 4: Same as Test 3, but with Professional Products Hurricane Vortec intake manifold, 1/2-inch phenolic spacer, 37 degrees ignition timing Peak Values are in bold.

Sources

Westech Performance Group
Mira Loma, CA
951-685-4767
WestechPerformance.com
Lunati
662-892-1500
www.lunatipower.com
Rockett Brand Racing Fuel
Mount Prospect, IL
847-795-8400
RockettBrand.com
Chevrolet Performance Parts
Detroit, MI 48232
800-577-6888
www.gmperformanceparts.com
Lucas Oil
Corona, CA 92880
951-270-0154
www.lucasoil.com
E3 Spark Plugs
Ponte Vedra, FL
www.e3sparkplugs.com

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