Will this camshaft fit my 1966 Chevrolet 396 Big Block?

No, this specific camshaft (part #11-240-4) will not fit 1965-1966 396 Big Block engines. These early models have an oiling groove in the rear journal that requires a different camshaft. Please contact us for assistance with ordering the correct cam for those specific applications.

What kind of performance improvements can I expect with this camshaft?

This camshaft is designed to improve your engine's breathing and power output. It's particularly effective when paired with improved intake components and headers, offering a noticeable boost in responsiveness and overall performance for your Big Block engine.

Does this camshaft come with lifters or other installation hardware?

This product is for the camshaft only. Lifters and other necessary installation hardware, such as valve springs and pushrods, are sold separately and should be chosen based on your engine's specific needs and the camshaft's specifications.

COMP Cams Camshaft CB XM 278H-12 11-240-4

Name: COMP Cams Camshaft CB XM 278H-12
Brand: COMP Cams
Price: 323.69 USD
Availability: InStock

COMP Cams Camshaft CB XM 278H-12

$323.69

On Backorder

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

COMP Cams Xtreme Marine hydraulic flat camshaft for Chevrolet Big Block 396-454 engines. Part# 11-240-4.

Key Features

Fits Chevrolet Big Block 396-454 engines originally equipped with flat tappet camshafts.
Hydraulic flat tappet design for automatic valve lash adjustment and simplified maintenance.
Intake duration is 234 degrees at .050 inch lift.
Exhaust duration is 244 degrees at .050 inch lift.
Intake and exhaust lift is .495 inches.
Designed for improved performance, especially with upgraded intake and headers.

⚠️ CA WARNING: This product can expose you to chemicals known to the State of California to cause cancer and/or birth defects or other reproductive harm. Learn more

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Will this fit your vehicle?

Product Details

If you're looking to wake up your Chevrolet Big Block engine, this COMP Cams Xtreme Marine camshaft is a solid option. Designed for 396 to 454 cubic inch engines originally equipped with flat tappet camshafts, this cam is built to improve your engine's breathing and power output, especially when paired with better intake components and headers. It features a hydraulic flat tappet design, meaning it uses oil pressure to adjust valve lash automatically, simplifying maintenance compared to solid lifter cams.

This camshaft has a duration of 234 degrees on the intake and 244 degrees on the exhaust at .050 inch lift, with a .495 inch lift on both sides. These specs are tuned for improved performance in marine applications, particularly with an 'A' impeller jet drive, and will benefit from improved intake flow and headers to really sing. It's a well-built component from COMP Cams, a popular name in performance engine parts, designed to give your Big Block a noticeable boost in power and responsiveness.

Please note that this camshaft is not CARB approved and cannot be shipped to California. Also, be aware that 1965-1966 396 Big Block engines have a rear journal oiling groove that requires a specific camshaft; this part number will not fit those particular early models. If your engine has that specific groove, you'll need to contact us to arrange for a different cam.