Usage:
CONNECTING ROD WITH TAPERED PIN END
CONNECTING ROD WITH STRAIGHT PIN END
POSITIONING PIN BEARING
MARKS FOR TIGHTENING CONNECTING ROD BOLTS
(1) Bore in connecting rod for piston pin bearing ... 2.1825 ± .0005 in.(55.436 ± 0.013 mm)
Tight fit between connecting rod eye and piston pin bearing ... .002 to .004 in.(0.05 to 0.10 mm)
NOTE: Connecting rod must be heated for installation of piston pin bearing. Do not use a torch.
Heat connecting rod to temperature of (maximum) ... 400° F(215° C)
NOTE: Piston pin bearing junction must be assembled within either area "A" (90 ± 10° from the centerline through the connecting rod bores) as shown.
(2) Bore in connecting rod for bearing with nuts tight to specifications (6) ... 4.0748 ± .0005 in.(103.500 ± 0.013 mm)
(3) Distance between center of bearings ... 10.300 ± .002 in.(261.62 ± 0.05 mm)
(4) Bore in bearing for piston pin (new) ... 2.0012 ± .0003 in.(50.830 ± 0.008 mm)
Diameter of piston pin (new) ... 1.9998 ± .0002 in.(50.795 ± 0.005 mm)
Maximum permissible clearance between bearing and piston pin (worn) ... .003 in.(0.08 mm)
* 7N3231, 6N3911 Connecting Rod (Later)
(5) Bore in bearing for crankshaft ... 3.8236 to 3.8258 in.(97.119 to 97.175 mm)
Clearance between bearing and crankshaft (new) ... .0028 to .0066 in.(0.071 to 0.168 mm)
Maximum permissible clearance between bearing and crankshaft (worn) ... .010 in.(0.25 mm)
6N1828, 4N371 Connecting Rod (Earlier)
(5) Bore in bearing for crankshaft ... 3.8236 to 3.8258 in.(97.119 to 97.175 mm)
Clearance between bearing and crankshaft (new) ... .0028 to .0066 in.(0.071 to 0.168 mm)
Maximum permissible clearance between bearing and crankshaft (worn) ... .010 in.(0.25 mm)
(6) Tightening procedure for connecting rod bolts:
a. Put 2P2506 Thread Lubricant on bolt threads and contact surfaces of nut and cap.
b. Tighten both nuts to ... 60 ± 6 lb. ft.(80 ± 8 N·m)
c. Put a mark on each nut and end of bolt as shown.
d. Tighten each nut from mark ... 120 ± 5°
NOTE: Bearings are available in .025 in. (0.64 mm) and .050 in. (1.27 mm) smaller than original size.
*7N3231, 6N3911 Connecting Rods used only with 6N3907 Crankshaft Assembly in engines with Serial Number 90U452-Up and 91U128-Up.
Make reference to Special Instruction Form Nos. GMG02394 & GMG02395 for information to check and recondition connecting rods.