Chevy Small Block Build - Mildly Amusing

How to build a recession-proof 365 hp small-block.

Richard Holdener Oct 1, 2012 0 Comment(s)
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Knowing what goes into a motor must also eventually come out, we equipped the small-block with a set of 1-5/8-inch FlowTech headers. The headers were run into a 2.5-inch dyno exhaust featuring 18-inch collector extensions. Naturally a full-length exhaust system may rob the motor of a few horses, so too will the installation of the accessories and water pump. Our dyno session included a CSI electric pump, no accessories, and the MSD distributor set to provide 35 degrees of total advance. The ported cast iron heads seemed to run best at 35 degrees, something we attribute to the minor combustion chamber polishing performed as part of the porting.

While we were anxious to find out if the combination produced the desired results, we curbed our impatience and allowed the motor a good 40-minute break-in period. After a few short whacks to verify the air/fuel curve, we let the hammer fly and were rewarded with peak readings of 367 hp and a whopping 422 lb-ft of torque. The mild cam timing allowed the motor to produce peak power at just 5,200 rpm, a fact that should help ensure a long life.

The low peak-power rpm also produced an impressive torque curve. Not only did the motor produce 422 lb-ft at 3,900 rpm, but the 0.030-over 350 produced over 400 lb-ft for nearly a 2,000-rpm spread. Even way down at 2,500 rpm, the impressive combination produced nearly 400 lb-ft of torque. It is torque like this that will allow this 365hp version to motor past the high-winding L76 327s of yesteryear. Given the mild cam, ported stock heads, and minimal compression, we were quite pleased with the entire powercurve.

That the motor made peak power at only 5,200 rpm indicates that we had plenty of power potential left, should we elect to run a wilder cam profile or a set of aftermarket cylinder heads. Is the build up of a 365hp small-block that thumps out 422 lb-ft. of torque earth shattering? Probably not. But besting the small-block legends of yesteryear using ported smog heads, a mild cam, and 9.1:1 compression should be considered at the very least, mildly amusing.

Spec Sheet 365-HP 355

  • Block: 4-bolt Chevy
  • Crank: Cast 3.48-inch Stroke
  • Rods: LT-1 Pink 5.7 inches
  • Pistons: JE Pistons Flat-Top Replacement Single-Eyebrow (9.1:1)
  • Bore Size: 4.030 (0.030 over)
  • Compression Ratio: 9.1:1 with 76 cc chamber
  • Heads: Chevy Iron 882 casting-Hand Ported by L&R Automotive
  • Intake Valve Size: 2.02 (originally 1.94)
  • Exhaust Valve Size: 1.60 (originally 1.50)
  • Cam: Comp Crane PowerMax
  • Lift: 0.427 n, 0.454 ex
  • Duration (@ 0.050): 204 in, 216 ex
  • Lobe Separation: 110 degrees
  • Intake Manifold: Edelbrock Performer RPM Air Gap
  • Carburetor: Demon Fuel Systems 650 Street Demon
  • Distributor: MSD Billet
  • Headers: Flow Tech 1 5/8-inch
  • Exhaust: 2.5-inch (Dyno)
  • Mufflers: None

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15 The moment of truth finally came and our traditional small-block did not disappoint. The 0.030-over 350 pumped out an impressive 367 hp and an even more amazing 422 lb-ft of torque. With numbers like that, you can’t help but find this build up at least mildly amusing!

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16 The one thing you should notice even before the impressive peak power number is the broad torque curve. Naturally all the bench racing centers on the 367 horsepower, but the fact is it will be the 400-plus lb-ft produced from 2,900 rpm to 4,700 rpm that will provide the most smiles per mile. Heck, even down as low as 2,400 rpm, the small-block belted out 390 lb-ft of torque. It is this kind of tire-shredding torque that will provide crisp throttle response and plenty of passing power. The impressive thing is, this power was produced with a set of ported factory cast iron cylinder heads, a mild emissions-legal cam, and pump-gas-friendly compression. If cared for with regular oil changes and tune-ups, this motor should have no trouble providing years and years of trouble-free performance. As a side note, it would also make one heck of a street-driven replacement for that valuable original L76.

Sources

Crane Cams
Daytona Beach, FL 32117
866-388-5120
http://www.cranecams.com
L&R Automotive
Sante Fe Springs, CA 90670
562-802-0443
www.lnrengine.com
JE Pistons
Huntington Beach, CA 92649
714-898-9763
www.jepistons.com

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