4-Pattern 229/239 IB, 231/241 OB Hydraulic Roller Cam for OE Roller SBC


Hydraulic Roller: 4-Pattern 281QI08 - Great all around choice for street applications in modified engines and 2500+ stall or manual transmissions.*

COMP Cams® 4-Pattern Camshafts are hydraulic rollers designed to optimize valve events based on runner length and feature a large increase in both area under the curve and stability at high RPM

To make the most power from your engine, you need to optimize the air ingested and captured by avoiding valves closing too soon or too late. Any conventional center layout single throttle body or carbureted V8 intake manifold features longer outboard runners and shorter inboard runners, meaning that each valve event should occur at a different moment.

COMP Cams® 4-Pattern Camshafts are the very first series of cams designed to accommodate this difference in length and avoid valves closing at the wrong times. NASCAR teams have been using camshafts designed this way for years, and using lessons learned along with them, COMP Cams® has designed a series of cams that optimizes valve events and features a large increase in both area under the curve and stability at high RPM.

The camshafts feature four different lobe patterns with one intake and exhaust design for outboard runners, and another intake and exhaust design for the inboard runners. While the four inboard cylinders are all the same grinds, the outboard exhaust openings are two degrees earlier, with outboard intake closings coming two degrees later. This is the first ever use of technology in street vehicles to balance air/fuel ratio per cylinder and can net you a possible 1000+ RPM over other hydraulic rollers and anywhere from 5-20+ horsepower peak to peak, depending on cylinder head flow.

The 4-Pattern hydraulic roller cams are CNC-Machined from steel billet cores with cast iron distributor drive gears. The cams also feature a tight lobe separation for both excellent performance and a throaty sound.

*Upgraded valve train components and aftermarket cylinder heads required

4-Pattern Vs. Xtreme Energy

More Information
Make Chevrolet
Engine Family: Chevrolet 305-350 c.i. 8 Cylinder O.E. Roller (1987-1998)
RPM Operating Range: 2,300-6,600
Grind Number: 281QIO8
Cam Type: Hydraulic Roller
Lifter Style: Hydraulic Roller
Camshaft Series: 4-Pattern
Camshaft Gear Attachment: 3-Bolt
Usage: Street/Strip
Valve Springs Required: Yes
Camshaft Material: Billet Steel
California Proposition 65: WARNING: Cancer and Reproductive Harm P65Warnings.ca.gov
Advertised Inboard Intake Duration: 281
Advertised Inboard Exhaust Duration: 293
Advertised Outboard Intake Duration: 283
Advertised Outboard Exhaust Duration: 295
Inboard Intake Duration at .050 Inch Lift: 229
Inboard Exhaust Duration at .050 Inch Lift: 239
Outboard Intake Duration at .050 Inch Lift: 231
Outboard Exhaust Duration at .050 Inch Lift: 241
Inboard Intake Valve Lift: 0.619
Inboard Exhaust Valve Lift: 0.606
Outboard Intake Valve Lift: 0.622
Outboard Exhaust Valve Lift: 0.61
Lobe Lift Intake: .389 / .387
Lobe Lift Exhaust: .381 / .379
Lobe Separation: 108.5 OB/107.5 IB
Intake Centerline: 103 / 102
Assembly Lubricant Included: No
Valve Timing @ 0.006 Lift:
Exhaust Close ATDC: 35 / 35
Exhaust Open BBDC: 80 / 78
Intake Open BTDC: 37 / 37
Intake Close ABDC: 66 / 64