What torque should a 3/8" 8740 rod cap screw be tightened to?

40–45 FT-LBS with moly lube on the threads, with a bolt stretch (elongation) of 0.0050–0.0060".

What if I use motor oil instead of moly lube on the rod bolt threads?

The sheet says to add 10 FT-LBS to the listed torque values when torquing with motor oil.

What rod bearing oil clearance does this sheet specify?

Rod bearing clearance of 0.002–0.003" and side clearance of 0.015–0.025".

What small-end (wrist pin) clearance is specified?

0.0009–0.0015" clearance for floating-pin type; for press-fit type the small end is 0.0006–0.0009" smaller than the pin.

Can rod caps be swapped between rods?

No — the sheet says to ensure the original pair is installed together, because the cap and rod are honed together at the factory.

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Connecting Rod Bolt Torque Specs & Clearances - 8740 Cap Screw Instruction Sheet

Connecting rod bolt torque and oil-clearance spec sheet for 8740 cap screws

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Engine-builder spec page listing rod-bolt torque-by-elongation for 8740 cap screws (8mm 30-35, 9mm/5-16 40-45, 7-16 65-70 ft-lb) plus rod, pin and side clearances.

AI caption September 2011 · Photo 623 of 1264

This document is a photographed page from an aftermarket connecting rod installation instruction sheet, shown alongside two twelve-point connecting rod cap screws (bolts) laid on the paper. The page warns about residues that may cause gouging and seizing on threads, then lists the oil clearances the installer must verify: rod bearing clearance of 0.002–0.003", small end clearance of 0.0009–0.0015" for floating-pin type, 0.0006–0.0009" (smaller than pin) for press-fit type, side clearance of 0.015–0.025", and a reminder to use a narrow bearing on larger journal radii. It then gives torque specifications for 8740 chromoly cap screws when lubricated with moly lube: 8mm at 30–35 ft-lbs (elongation 0.0055–0.0070"), 9mm at 40–45 ft-lbs (0.0055–0.0065"), 5/16" at 30–35 ft-lbs (0.0060–0.0070"), 3/8" at 40–45 ft-lbs (0.0050–0.0060"), and 7/16" at 65–70 ft-lbs (0.0065–0.0075"). A note adds 10 ft-lbs to torque values if motor oil is used instead of moly lube. The page ends by instructing that original cap-and-rod pairs must stay together because they are honed together at the factory.

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Frequently asked questions

What torque should a 3/8" 8740 rod cap screw be tightened to?: 40–45 FT-LBS with moly lube on the threads, with a bolt stretch (elongation) of 0.0050–0.0060".
What if I use motor oil instead of moly lube on the rod bolt threads?: The sheet says to add 10 FT-LBS to the listed torque values when torquing with motor oil.
What rod bearing oil clearance does this sheet specify?: Rod bearing clearance of 0.002–0.003" and side clearance of 0.015–0.025".
What small-end (wrist pin) clearance is specified?: 0.0009–0.0015" clearance for floating-pin type; for press-fit type the small end is 0.0006–0.0009" smaller than the pin.
Can rod caps be swapped between rods?: No — the sheet says to ensure the original pair is installed together, because the cap and rod are honed together at the factory.