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Small block Chevy intake manifold torque specs and sequence

Gen I, pre-Vortec twelve-bolt pattern, stock hardware.

Pre-Vortec small block Chevy intake bolts take 30 ft-lbs with a cast iron manifold and 20 to 25 ft-lbs with aluminum. Run three passes from the center pair outward, with non-hardening sealer on the threads.

30ft-lbs

Cast iron manifold, 3/8"-16 (20–25 ft-lbs for aluminum)

Pass 1 3 passes, center outward

Thread prep: Non-hardening sealer on the threads.

Version	Torque	Notes
Cast iron manifold	30 ft-lbs	Summit, JEGS, Spelab and RacingJunk all say 30.
Aluminum aftermarket manifold	20–25 ft-lbs	JEGS says 25; Spelab says 20 to 25.

Intake bolt pattern

Twelve bolts on the pre-Vortec manifold, sitting in three pairs per side rather than an even row. They straddle the ports. Front of the engine is past bolts 12 and 10; the rear is past 6 and 8. The center pair on each side goes first (1 to 4), then the rear pairs (5 to 8), then the front pairs (9 to 12), crossing side to side as you go. Run three passes, stepping up evenly to final torque. Vortec and 1987–95 center-bolt heads use different patterns.

Watch outManifold material changes the number. Most builds running an aftermarket aluminum intake should be at 20 to 25, not 30. The cast iron figure will crack aluminum bolt bosses. This figure is also for the pre-Vortec twelve-bolt pattern only; Vortec and the 1987–95 center-bolt heads are different fitments entirely.

Sources disagree on what sets the numberSources agree there is a split at 30 versus 20 to 25, but not on which material decides it. Summit qualifies its 30 by cast iron heads; Spelab qualifies the same figure by a cast iron manifold; JEGS's wording could be read either way. The split here follows manifold material, since that is what takes the clamp load and what cracks. If you are running an aluminum intake on cast iron heads, the most common combination on this engine, the two readings disagree, and the lower figure is the safer one.

If you are not using stock bolts with oil

Hardware	What to do
Stock bolts, light engine oil	The condition the published figures assume. Use the figure as printed, with the thread prep noted above.
Stock bolts, dry threads	Published figures assume lubricated threads. Dry, more of the effort goes into friction and the bolt ends up with less clamp load than the number implies. Prep the threads as specified, then use the standard figure.
Stock bolts, moly lube	Moly cuts friction, so the same wrench reading produces more bolt tension than the figure was written for. Using the standard number with moly on the threads over-stretches the fastener. Use the lubricant maker's correction, or switch to engine oil.
ARP bolts or studs	Do not use the figures on this page. ARP fasteners run at a different clamp load and their torque is tied to their own assembly lube. Use the sheet in the box, or look up your part number.

Where these numbers come from

Source	Published figure
Summit Racing	intake manifold bolts, cast iron heads, 30 ft-lbs
JEGS	cast iron heads with non-hardening sealer 30 ft-lbs; aluminum intake 25 ft-lbs
Spelab	cast iron OEM intake 30 ft-lbs; aluminum aftermarket 20–25 ft-lbs, three passes
RacingJunk	30 ft-lbs in a two-step sequence

Intake bolt pattern

If you are not using stock bolts with oil

Where these numbers come from

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