Words And Photos: Richard Holdener

Let’s face it, building a small block means different things to different people. For some, a simple stock rebuild is all that is necessary to power their daily driver or transportation truck. For others, they might be looking for something a bit more sporty, but something that still serves as transportation. Naturally the needs of these street/strip enthusiasts differ from that of a daily driver, and even of those looking for maximum performance.

What the discussion comes down to is there are different levels of performance for different enthusiasts. Normally we concentrate our efforts on one particular combination, but this time out we decided to cater to a wider audience by illustrating not one but three different levels of performance. Think of them as 300-hp, 400-hp, and 500-hp, street, street/strip, and race or even level 1,2, and 3, but no matter what the label, we will illustrate combos that fit each level. Even if your current needs are best met by level 1, the others will show you what is possible when it comes time to Level Up!

Level 1: 300-HP 350 Chevy
Short Block-Junkyard 350 Chevy (late model 1-piece rear seal)
Heads: Stock Vortec
Cam: Stock Truck Hydraulic Roller
Rockers: Stock Stamped Steel
Intake: Edelbrock Performer RPM
Carb: Holley 650 HP
Exhaust: 1 5/8-inch Headers

Building a 300-hp small block Chevy is as easy (and inexpensive) as dropping by your local wrecking yard and yanking out a 350 truck motor. We chose a late-model, hydraulic roller 350 equipped with Vortec heads and a 1-piece rear main seal. We liked the factory hydraulic roller cam and lifters and when upgrading, know there are plenty of cam profiles available. The hydraulic roller cams are more expensive than the traditional hydraulic flat tappet cam but not having to worry about cam break in and possible damage is more than worth the extra expense.

The Vortec heads are the best flowing conventional (production) small block heads, so there is plenty of potential left in the stock castings. To exceed 300 horsepower, all we had to do was replace the TBI or CPI induction system with an Edelbrock RPM intake and Holley 650 HP carb (others will work as well at this power level). Run with Hooker headers and an electric water pump, the junkyard jewel produced 313 hp at 4,600 rpm and 398 lb-ft of torque at 3,400 rpm. The stock cam timing minimized power production, but the torque curve exceeded 390 lb-ft from 3,000 rpm to 4,000 rpm.

Level 2: 400-HP 350 Chevy
Short Block-350 Chevy Flat-Top JE Pistons
Heads: 200 CC RHS 2.02./1.6 valves 64cc chambers
Cam: COMP Hydraulic Flat Tappet XE274H (.490/.480 lift, 230/236 duration, 110 LSA)
Rockers: COMP Cams Magnum 1.5-Ratio Roller
Intake: Street Master Crosswind
Carb: Holley 750 HP
Exhaust: 1 3/4-inch Headers

Stepping up to 400 horsepower means adding a decent set of heads and a performance camshaft. We could well have used the stock 300-hp short block from the wrecking yard for this 400-hp example, but this test 350 featured a set of JE forged, flat-top pistons with valve reliefs and a set of 6.0-inch Street Master forged connecting rods. The power producers on this 400-hp version included a COMP XE274H (hydraulic flat-tappet) cam, 200cc (as-cast) RHS heads and a Streetmaster Crosswind intake. The RHS heads were a significant step up in flow and performance compared to the stock Vortec heads on the 300-hp version. The XE274H cam offered .490 lift, a 230/236-degree duration split and 110 lsa. The dual-plane Crosswind intake ensured both plenty of power and a broad torque curve. The 400-hp combination also featured a Holley 750 HP carb, MSD ignition and Lucas synthetic oil. Run on the dyno, the mild (but powerful) small block produced peak numbers of 414 hp at 5,900 rpm and 415 lb-ft of torque at 4,100 rpm. Torque production exceeded 400 lb-ft from 3,450 rpm to 5,100 rpm.

Level 3: 500-HP 372 Chevy
Short Block-Dart SHP 372 Chevy Mahle Flat-Top Pistons
Heads: AFR 195 Eliminator Heads (Comp Version) 2.08./1.6 valves
Cam: COMP XR300HR Hydraulic Roller (.562/.580 lift, 248/254 duration, 110 LSA)
Rockers: COMP Roller 1.5
Intake: Edelbrock Super Victor Single-Plane
Carb: Holley 950 Ultra HP
Exhaust: 1 3/4-inch Headers

A 500-hp small block is a serious animal and for this one we stepped up in displacement, compression and cam timing. The high-horsepower combo started out life as a Dart SHP short block that included 4.125-inch bore and standard (350 Chevy) 3.48-inch stroke. With the short block ready for action, we stepped up to some serious power producers. The upgrades to the SHP small block included a set of AFR 195 Eliminator heads (Competition version), a wild XR300HR hydraulic roller cam (.562/.580, 248/254 duration and 110 LSA) and Edelbrock Super Victor intake. Along for the ride was a Holley 950 Ultra HP carb, Meziere electric water pump and COMP Gold roller rockers. Equipped with this hardware, the big-bore small block produced an amazing 515 hp at 6,200 rpm and 464 lb-ft of torque at 4,500 rpm. Had this been a smaller 350-inch motor, the peak power would have occurred higher in the rev range with a commensurate loss in low-speed torque, but the increased bore size offered by the SHP short block allowed the motor to exceed 500 hp at just 6.200 rpm.

Sources

ARP
arp-bolts.com

Air Flow Research
airflowreaserch.com

COMP Cams
compcams.com

Dart
dartheads.com

Edelbrock
edelbrock.com

Holley/Hooker
holley.com

JE Pistons
jepistons.com

Lucas Oil
lucasoil.com

MSD
msdignition.com

RHS Cylinder Heads
racingheadservice.com