Starting at the Wrecking Yard

The premise is straightforward: pull a running small block from a wrecking yard and upgrade it with aftermarket heads and a performance camshaft to see what the short block can deliver. The yards are full of small blocks, but selecting the right one requires discipline. Some arrived because they stopped running. Others are there because of sheet metal damage - meaning the engine was likely operational at the time. Those are the ones worth inspecting.

The selection process starts with a visual check: no holes in the block, no excessive rust, no burnt bearing smell. Removing a valve cover reveals service history - oil sludge and buildup indicate neglect, while a clean valvetrain suggests regular maintenance. The final check: pull the plugs and confirm the motor spins freely.

Small block project motors are readily available. This late-model hydraulic roller motor was purchased complete for less than $300 - confirmed to spin freely with plugs that indicated it had been running.

Establishing a Baseline

The stock cast-iron intake and Q-Jet carburetor were replaced with a dual-plane Speedmaster Eliminator intake and Holley 750 HP carb for dyno testing. Signs of a previous mild RV cam swap were evident - the otherwise stock motor produced just over 310 hp.

The motor chosen was a late-model small block with a one-piece rear main seal, hydraulic roller camshaft, and 4-bolt block - sourced from a one-ton truck application. The stock accessories, cast-iron intake, and Q-Jet carburetor were removed. In their place: a dual-plane Speedmaster Eliminator intake and Holley 750 HP carburetor. A Meziere electric water pump replaced the accessories, and an MSD distributor replaced the factory HEI. Testing was conducted with 1 3/4-inch long-tube headers.

The wrecking-yard motor produced 312 hp at 5,500 rpm and 354 lb-ft of torque at 3,800 rpm. That output is approximately 30 hp above what similar low-compression stock 350s typically produce in this configuration, which suggests the previous owner had installed a mild aftermarket camshaft.

The Upgrade: COMP Cam and RHS Aluminum Heads

The COMP XR274HR cam: .502/.510 lift split, 224/230-degree duration split, 110 LSA. The late-model hydraulic roller block requires a dedicated cam snout designed for the factory cam retaining plate.

The factory hydraulic roller lifters were in good condition and reused for the new cam.

The late-model block included factory provisions for the hydraulic roller cam, including the cam retaining plate.

The unknown cam was removed and the COMP XR276HR grind installed.

The unknown camshaft was replaced with a COMP XR276HR. Camshaft timing is the foundation of street-oriented performance, and this profile was selected for daily-driver duty: .502/.510 lift split, 224/230-degree duration split, 110-degree lobe separation angle.

For the heads, the factory cast-iron units were replaced with as-cast RHS 200cc Pro-Action aluminum heads. The upgrade delivered three measurable improvements. First, reduced weight - aluminum versus cast iron. Second, improved airflow - the RHS 200cc ports outflowed the stock heads by nearly 70 cfm. Third, increased compression - the smaller 64cc combustion chambers (down from 76cc) raised static compression by more than a full point. On a low-compression truck motor, that compression increase alone translates directly to output.

RHS Pro-Action aluminum cylinder heads: a substantial improvement over the stock cast-iron smog heads in flow, weight, and compression.

Even in as-cast form, the 200cc intake ports on the RHS heads outflowed the stock castings by nearly 70 cfm.

Exhaust flow matched the intake improvement. The spring package was configured for the hydraulic roller cam.

The smaller 64cc combustion chambers - down from 76cc - raised static compression by more than one full point on the low-compression short block.

The Speedmaster Eliminator dual-plane intake was retained for the upgraded combination. The high-rise design delivered a strong torque curve through 6,000 rpm.

Dyno Results

The RHS heads were installed with Fel-Pro head gaskets and ARP head studs. The COMP cam used the existing factory hydraulic roller lifters. With the upgrade complete, the Boneyard Build produced 420 hp at 6,000 rpm and 415 lb-ft of torque at 4,200 rpm.

The gains were consistent across the entire operating range: an additional 35 lb-ft of torque as low as 3,000 rpm, building to over 100 additional horsepower at 6,000 rpm. The mild cam profile and free-flowing heads delivered a broad, usable powerband - exactly what a dual-purpose street motor requires.

Baseline (stock heads, unknown cam, Speedmaster Eliminator intake): 312 hp at 5,500 rpm / 354 lb-ft at 3,800 rpm

Modified (RHS 200cc Pro-Action heads, COMP XR276HR cam, Speedmaster Eliminator intake): 420 hp at 6,000 rpm / 415 lb-ft at 4,200 rpm

A sub-$300 wrecking-yard small block, an aluminum head swap, and a cam upgrade. The short block was never touched. The results confirm what makes the small-block Chevy platform endure: even a high-mileage truck motor responds to quality components with measurable, repeatable gains.