Mopar Gen I Hemi V8

Intro

The early Hemi is not a 426 with old jewelry.

That matters because the 331, 354, and 392 live in their own early Chrysler Hemi world. The heads are huge, the parts are expensive, the top end is different, and the hot-rod aftermarket has been mixing old iron and new hardware for decades. Treat it like a wedge, a 426 Hemi, or a modern crate engine and the correction gets expensive.

General Torque Specs

Bottom End		Top End
Main Cap Bolts	85 lb-ft	Cylinder Head Bolts	85 lb-ft2
Main Studs	85 lb-ft1	Cylinder Head Studs	100 lb-ft2
Connecting Rod Bolts	45 lb-ft	Rocker Shaft / Stand Hardware	use actual rocker-system spec3
Oil Filter Bolt	25 lb-ft	Spark Plugs	30 lb-ft
Oil Pan Bolts	15 lb-ft	Valve Cover Bolts	snug only4
Intake and Exhaust		Driveline Side
Intake Manifold Bolts	30 lb-ft2	Flywheel / Flexplate Bolts	55 lb-ft5
Exhaust Manifold Stud Nuts	25 lb-ft	Torque Converter Bolts	270 in-lb5
Carburetor Mounting Nuts	7-10 lb-ft4	Bellhousing / Flywheel Housing Bolts	50 lb-ft5
		Starter Mounting Bolts	50 lb-ft5
External Engine
Harmonic Damper Hub Bolt	135 lb-ft	Camshaft Timing Gear Bolt and Washer	35 lb-ft
Camshaft Thrust Plate Bolts	15 lb-ft	Timing Cover Bolts	15 lb-ft
Distributor Clamp Bolt	15 lb-ft

¹ Main studs are listed at the same value as main cap bolts in the early Hemi Hot Heads table. Aftermarket stud kits still follow the stud maker’s lube and torque instructions.

² Head bolts and head studs use different values. Match the fastener type. Aftermarket heads, studs, replacement fasteners, and special gaskets use their own instructions.

³ Rocker hardware varies by stock setup, adjustable conversion, aftermarket shaft system, stands, and rebuild parts. Use the actual rocker-system spec.

⁴ Thin covers, carburetor flanges, and cork-style gaskets distort easily. Tighten evenly and do not turn seep control into bent metal.

⁵ Adapters, transmission swaps, race flywheels, replacement driveline hardware, and non-stock starters follow the part maker.

Aftermarket bolts, studs, rods, aluminum heads, intake manifolds, rocker hardware, replacement fasteners, adapters, and modified early Hemi parts use the part maker’s number and lube instructions. Don’t use this chart to overrule the parts in your hand.

A range is not a game of horseshoes. If a matched set shows 7-10, don’t give one carb nut 7, the next one 9, and the last one whatever your elbow liked. Pick one value in the range and use it consistently across the set unless the real procedure says certain fasteners get different numbers.

Notes

• Early Chrysler Hemi hardware is not cheap enough for guesswork. If the parts are original, inspect them. If the parts are aftermarket, follow the maker.
• 331 / 354 and 392 parts can look close enough to start bad ideas. Deck height, heads, intake fit, water crossover parts, and hot-rod adapters are where lazy interchange turns into expensive comedy.
• Head bolts and head studs do not use the same value. Don’t swap the fastener type and keep the old number because the wrench was already set.
• Rocker gear is a parts-specific area. Stock shafts, adjustable conversions, aftermarket stands, and roller hardware do not all get one magic torque value.
• Valve covers, oil pans, carburetor flanges, and old gasket rails are easy to distort. If the gasket squeezes out, that was not extra sealing. That was you.

Common Mistakes

• Using 426 Hemi habits on a Gen I Hemi because both engines have famous valve covers.
• Treating 331 / 354 and 392 intake or top-end parts like everything swaps cleanly because it all says early Hemi.
• Using the head-bolt value on head studs, or the stud value on bolts, because “close enough” wanted to buy parts.
• Inventing one rocker-shaft torque number for whatever old, rebuilt, converted, or aftermarket rocker gear happens to be on the engine.
• Using adapter, flywheel, or transmission-swap hardware with factory-style torque numbers after the parts came with their own instructions.
• Reading a range and scattering random values across carburetor nuts, cover bolts, or matched driveline fasteners like that was ever a plan.

Bottom Line

The Gen I Hemi is big, expensive, beautiful old Chrysler iron.

That does not make it simple.

Use early Hemi numbers, identify the actual 331 / 354 / 392 hardware, follow the fastener and rocker-gear instructions in front of you, keep matched fasteners consistent, and don’t let famous valve covers do your thinking.