What the Camshaft Controls
The camshaft sets lift (how far each valve opens), duration (how long it stays open relative to crank rotation), and overlap between the intake and exhaust events. Unlike the gear-driven 212/224 engines, the Predator 301cc is a traditional OHV pushrod engine driven by a timing chain. This gives you a bit of forgiveness during installation, but also means you must manage chain tension and guide wear.
A cam swap on the 301cc is a major breathing upgrade. Because the 301cc already has a larger displacement than the 212, it responds incredibly well to increased duration and lift, shifting the powerband higher and pulling much harder through the mid-to-top RPM range.
Because the 301cc uses a timing chain, always inspect the chain guides and tensioner while the cover is off. A worn chain can jump a tooth, destroying your timing. Additionally, aggressive cams with high lift can alter pushrod geometry. Ensure your pushrods are the correct length for your specific cam to prevent binding the rocker arms at max lift.
Cam Options at a Glance
| CAM TIER | LIFT | DURATION @ .050 | POWERBAND | STATUS |
|---|---|---|---|---|
| Stock / Stock-Legal | ~.220 in | ~230° | Low-end torque | GOVERNED / CLASS |
| Stage 1 (Mild) | ~.250 in | ~250° | Broad torque | BOLT-ON |
| Stage 2 (Aggressive) | ~.280 in | ~265° | Mid-to-top pull | MOD PREP |
| Race-Only (High Lift) | .300+ in | 275°+ | Top-end scream | RACE ONLY |
Treat these as reference points, not guarantees — confirm exact figures on the cam's own spec sheet before buying.
Choosing Your Cam
Valve Spring Pairing
| SPRING RATE | RPM BEFORE FLOAT* | STATUS |
|---|---|---|
| Stock | ~4,500 | CAUTIOUS |
| 18 lb (Stage 1 pairing) | ~5,500–6,000 | SAFE* |
| 22–26 lb (Stage 2 pairing) | 6,500+ | SAFE* |
| Full race package | 7,500–8,000 | RACE ONLY |
*Assumes billet rod + flywheel are already installed. Confirm exact spring rate against your specific cam, since recommendations vary by grind and lift.
Never install stiffer springs on the 301cc without upgrading the connecting rod. The stock cast rod becomes the failure point around 5,500 RPM. Heavier springs alone will just trade valve float for a thrown rod at roughly the same RPM.
Supporting Parts Checklist
Tools & Installation
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01
Drain the engine oil and remove the spark plug. Unbolt and remove the valve cover to expose the rocker arms and pushrods. TIP: Keep your rocker arms, nuts, and pushrods organized. Reinstalling them in their exact original positions helps with break-in.
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02
Remove the rocker arm nuts, lift out the rocker arms, and push the pushrods down and out of the block.
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03
Remove the timing chain side cover. Use a pick to slide the timing chain off the cam gear. Unbolt the cam gear and carefully slide the stock camshaft out of the engine block.
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04
Apply a generous coat of assembly lube or high-zinc break-in oil to the new camshaft lobes and journals. Carefully slide the new performance cam into the block.
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05
Install the cam gear and torque the bolt to spec. Route the timing chain over the cam gear and crank gear. TIP: Ensure the timing marks (dots or dashes) on both the cam gear and crank gear are aligned perfectly. A chain driven engine gives you a little slack, but do not rely on it—get the marks dead-on.
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06
Install the pushrods back into their respective lifter cups. Reinstall the rocker arms and hand-tighten the nuts.
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07
Rotate the engine to Top Dead Center (TDC) on the compression stroke. Use a feeler gauge to set the valve lash. For most 301cc performance cams, set Intake to 0.003" - 0.004" and Exhaust to 0.004" - 0.005" (always verify with your cam manufacturer's spec sheet). TIP: Always set valve lash when the engine is completely COLD. Heat expansion will change your clearances.
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08
Reinstall the valve cover and timing chain side cover with new gaskets. Fill the crankcase with high-zinc break-in oil (or standard oil with a ZDDP additive).
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