Product details

Designed to deliver an aggressive, hard-hitting exhaust note at idle, the Thumpr camshaft series from COMP Cams also delivers excellent horsepower gains and a broad torque curve. A perfect choice for muscle cars and street rods, the Thumpr series' early intake valve opening and long exhaust duration create optimum overlap for that race car idle. The Thumpr grinds all require an aftermarket torque converter and lower gear ratio to ensure the drivetrain always puts the engine in its powerband. Additionally, Thumpr camshafts typically deliver reduced vacuum at idle, making a vacuum canister, pump or hydroboost a requirement for vehicles running power brakes. Street/strip, needs 9.5:1 compression, 2800+ stall, intake, gears and headers, very rough idle. Nitrided. Big Mutha' Thumpr NIT 243/257 Hydraulic Flat Cam for Chevrolet Small Block

Manufacturer fitment & guides

• Fits Chevrolet GEN 1 Small Blocks including the 262, 265, 267, 283, 302, 305, 307, 327, 350 and 400. Does not fit LT1/LT4, or factory roller Small Blocks built from 1985 and newer. GM gradually added roller camshafts to 305's and 350's from the mid 80's forward. Camaros/Firebirds/Corvettes received the roller cams early, but many trucks and SUV's had flat tappet cams until the mid 90's. Remove the intake or timing cover to confirm whether the block is a factory roller or flat tappet. Does not fit the LS1, LS2, LS3 or any LS-based 4.8, 5.3, 5.7, 6.0 and 6.2. 1955-1957 Chevrolet 265 engines require a groove on the 5th cam journal for oiling. Contact us for more information.

• Manufacturer-supplied application summary from Turn14; this may not be an exhaustive fitment list.

• Catalog ↗
• User 1 ↗
• COMP Cams manufacturer product and part-number catalog ↗

Part-specific notes

• Not CARB approved. Destination and intended-use restrictions must be checked before sale.
• Emissions acknowledgement required before purchase.
• California Proposition 65: Y

Manufacturer documents

• Catalog
• User 1