The 5.7L Hemi has 16 spark plugs — two per cylinder. Gap them to 0.045", torque to 13 ft-lbs, and replace all 16 even if only one is fouled.
Yes, sixteen. The Hemi's dual-plug design fires two plugs per combustion event for better burn and lower emissions. You don't get to skip half of them when one starts misfiring. There are eight coils — one per cylinder — and each coil fires both plugs on its cylinder through one boot direct to one plug and a small lead to the second. The driver-side plugs are manageable. The passenger-side plugs sit forward of the exhaust manifold heat shields and can fight you.
Plug spec: Champion RE14MCC4 (Mopar p/n SPRE14MCC4) is the OE plug. NGK TR55 (part 92174) is a common drop-in alternate that forum users have run without issue. Gap is 0.045". Torque is 13 ft-lbs — these are tapered-seat plugs, not crush-washer, and they will strip a head if you crank them down on feel. Use a torque wrench.
Pull the engine cover. Each coil is held by one 8mm bolt and one connector with a red lock tab. Lift the coil straight up; if it fights, twist it gently — there's a rubber boot grabbing the plug. The second plug on each cylinder sits below a short wire lead with its own boot. Pull that boot too. Blow compressed air around each plug well before removal so dirt doesn't fall into the cylinder.
Plugs come out with a 5/8" plug socket on a 3-inch extension and a swivel — the passenger-side rears need the swivel to clear the manifold. Inspect the old plugs (a quick read on running condition) and install the new ones with a small dab of anti-seize on the threads if you live in a salt state. Gap is set from the factory but verify with a feeler gauge. Torque to 13 ft-lbs. Dielectric grease on the boot interiors helps the next removal in 100K miles.
| Part | Vendor | Est. price |
|---|---|---|
| Mopar / Champion spark plug (5.7L Hemi, qty 16) | Mopar / Champion | ~$90 |
| NGK V-Power spark plug TR55 (alternate, qty 16) | NGK | ~$80 |
| Dielectric grease (small tube) | Permatex | ~$5 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.