SBC Xtreme Energy 248/254 LSA 110 Hydraulic Roller Camshaft Chevy Small Block XR300HR

The 12-444-8 is built for high-compression, high-stall SBC combinations. If your engine is below 10:1 compression or running a stock or near-stock converter, this cam will feel flat off the line and won't make the power it's designed for. The XR300HR starts making power at 3,200 RPM and pulls to 6,200 — under that, you're outside its operating window. Common builds that suit it: 383 stroker, 406 SBC, built 350 with AFR or Dart heads, drag and bracket cars.

No. The cam produces a very rough idle and significantly reduced manifold vacuum. Power brakes will be noticeably affected. A 3,500 RPM or higher stall converter is required to get the engine into its powerband off the line.

• 12-444-8 — camshaft only.
• K12-444-8 — cam plus matched hydraulic roller lifters.
• SK12-444-8 — cam, lifters and timing set (full retrofit kit).

If you're going from a flat tappet to a hydraulic roller, the SK kit is the better buy — the lifters and timing set are matched to the cam.

Comp Cams specifies springs PN 26987-16 and retainers PN 740-16. Running it on stock or mismatched springs will cause valve float, coil bind, or premature lobe wear. Always check installed height and coil bind clearance against your specific cylinder heads.

The 12-444-8 is designed for early non-roller SBC blocks (pre-1987) that didn't come from the factory with provisions for hydraulic roller lifters. Retrofit hydraulic rollers use a tie-bar lifter design and require a cam thrust button and wear plate, because non-roller blocks don't have the factory roller cam retainer plate.

The 12-443-8 (XR294HR) is one step milder — 242°/248° at .050", .560"/.580" lift. The 12-444-8 (XR300HR) adds duration and is the largest hydraulic roller in Comp's Xtreme Energy street range. Buyers stepping up from the 443 report a rougher idle but stronger top-end pull. If you're undecided, the 443 is the safer street pick; the 444 is for a committed build.

Comp Cams positions this grind for pro street and bracket racing. With a properly built short block, AFR or Dart aluminium heads, a single-plane intake and 1 5/8"–1 3/4" headers, a 383 SBC with this cam will typically make 450–500+ HP at the crank, with the curve favouring upper-mid to top end. Exact output depends on heads, compression, and tune — these are typical figures, not guaranteed.

Hydraulic roller cams don't require the high-pressure flat-tappet break-in, but Comp Cams still recommends a quality break-in oil with adequate ZDDP and a controlled start-up. Prime the oil system, run varied RPM between 1,500–2,500 for the first 20–30 minutes, and check lifter preload.

Not legal for use on emissions-controlled road vehicles. Comp Cams lists this as CARB-exempt for race/competition-only vehicles, and for federally certified vehicles pre-1967 meeting tailpipe standards for the year. In Australia, fitment to a registered ADR-compliant road vehicle will affect emissions compliance — confirm your state's rules before fitting.

• Stock fuel pump pushrod won't work with most retrofit roller setups on early blocks — check your engine year.
• Distributor gear: factory iron/steel gears can wear against a billet roller cam. Confirm gear material compatibility (Comp 12200 composite gear is a common solution).
• Pushrod length will likely change vs. a flat tappet — measure with a checking pushrod before ordering.