Connecting Rod Bearings

Replace the connecting rod bearings on a 1972 Ford F-100 302ci V8 by removing the oil pan, inspecting crankshaft journals, and installing new rod bearings with proper clearance verification.

Warnings

Tools required

Parts

• Connecting rod bearing set (Standard size or appropriate oversize) × 1 — Use OEM specification or Clevite CB-481P (standard)
• Oil pan gasket × 1 — Use OEM specification or Fel-Pro OS30400R
• Oil filter × 1 — Motorcraft FL-1A or equivalent
• Connecting rod bolts (if reusing is not recommended) × 8 — Use OEM specification
• Oil pan drain plug gasket × 1 — Use OEM specification
• RTV silicone sealant (oil-resistant) × 1 — Permatex Ultra Grey 82194 or equivalent
• Engine assembly lube × 1 — Use OEM specification

Fluids

• 10W-30 or 10W-40 conventional engine oil — 5 qt

Preparation

1. Disconnect negative battery cable
2. Drain engine oil completely and remove oil filter
3. Allow engine to cool to ambient temperature if recently operated
4. Mark all connecting rod caps with cylinder number and orientation (front/passenger side) using a paint pen before disassembly
5. Verify replacement bearings match the required size (standard or oversize) for your crankshaft
6. Clean work area and prepare clean assembly surface for components
7. If working with engine in vehicle: Raise vehicle and secure on jack stands, remove necessary exhaust components and crossmembers for oil pan access

Procedure

1. 1

   Remove oil pan
   Remove the oil pan bolts securing the pan to the engine block (typically 14-16 bolts depending on oil pan configuration). The front 2 bolts are accessed through the front sump area. Carefully lower the oil pan, breaking the gasket seal with a gasket scraper or pry bar if necessary. Do not pry on the gasket mating surfaces. If engine is in vehicle, you may need to raise the engine slightly using a floor jack under the front crossmember to gain clearance for pan removal past the front crossmember.
2. 2

   Remove oil pump pickup tube
   Remove the 2 bolts securing the oil pump pickup tube to the main bearing cap. Remove the pickup tube and screen assembly to provide clearance for connecting rod cap removal. Set aside for reinstallation.
3. 3

   Inspect and document rod positions
   Rotate the crankshaft using a socket on the harmonic balancer bolt to position each connecting rod at bottom dead center (BDC) for inspection. Verify that all 8 connecting rods and caps are clearly marked with their cylinder number (1-8) and orientation. Cylinders are numbered 1-4 on passenger side (right) front to rear, and 5-8 on driver side (left) front to rear. If any markings are unclear, re-mark them now with a paint pen on both the rod and cap.
4. 4

   Remove connecting rod caps
   Working on one cylinder at a time, remove the 2 connecting rod cap bolts from cylinder 1. Carefully remove the rod cap and lower bearing shell. Place the cap with its bolts and bearing in a clearly labeled container or position. Note the bearing's orientation (tang position) before removal. Repeat this process for all 8 cylinders, keeping each rod cap and bearing set separate and clearly identified.
5. 5

   Push pistons up and remove upper bearings
   Using a wooden dowel or plastic hammer handle (never metal), carefully push each piston/rod assembly up into its cylinder bore to access the upper bearing shell. Remove the upper bearing shell from each connecting rod, noting the tang position. Keep upper and lower bearing pairs together with their respective rod identification. Inspect removed bearings for wear patterns, scoring, or embedded debris.
6. 6

   Inspect crankshaft journals
   Clean all 4 connecting rod journals on the crankshaft thoroughly with lint-free rags and solvent. Inspect each journal visually for scoring, heat discoloration, or visible wear. Using a micrometer, measure each journal diameter at 4 positions (90-degree intervals) and at 3 locations along the journal length (center, and 1/4" from each edge) to check for out-of-round and taper conditions. The standard journal diameter for the Ford 302 is 2.1228"-2.1236". Maximum out-of-round tolerance is 0.0006". Maximum taper tolerance is 0.0006". Record all measurements. If any journal is beyond tolerance, the crankshaft requires grinding and undersize bearings must be used.
7. 7

   Inspect connecting rods
   Clean all connecting rod big end bores thoroughly. Using an inside dial bore gauge or telescoping gauge with micrometer, measure the big end bore diameter of each connecting rod with its cap installed and torqued to specification (19-24 ft-lb for this application, but verify before final installation). Standard bore diameter should be 2.1236"-2.1244". Check for out-of-round condition. Maximum out-of-round is 0.0005". Any rod exceeding this tolerance should be replaced or reconditioned.
8. 8

   Install new upper bearing shells
   Wipe the connecting rod big end bore clean and dry. Install the new upper bearing shell (without oil holes) into the connecting rod, ensuring the bearing tang engages the notch in the rod. The bearing should snap into place and sit flush. Do not file or force the bearing. Apply a light coat of assembly lube to the bearing surface. Repeat for all 8 connecting rods. Do not allow pistons to drop down and contact crankshaft journals.
9. 9

   Check bearing oil clearance with Plastigage
   Position cylinder 1 piston down so the rod bearing contacts the journal. Place a strip of Plastigage across the full width of the crankshaft journal, parallel to the crankshaft centerline. Carefully guide the rod down onto the journal without rotating it. Install the lower bearing shell (with oil hole) into the rod cap, ensuring tang engagement. Install the cap in its original orientation and install the rod bolts. Torque the bolts to the final spec of 19-24 ft-lb in two steps (15 ft-lb, then 19-24 ft-lb) without rotating the crankshaft. Remove the cap carefully without rotating the crankshaft. Measure the flattened Plastigage using the scale on the Plastigage envelope. Desired oil clearance for the 302 is 0.0008"-0.0015" for standard bearings. Maximum clearance is 0.0024". If clearance is excessive, verify journal diameter and bearing size. Repeat Plastigage check for all 8 connecting rods.
10. 10

    Final bearing installation
    Once all clearances are verified as acceptable, remove all Plastigage residue from journals and bearings using a clean rag. Apply a generous coat of assembly lube to both the upper bearing (already in rod) and lower bearing shell. Install the lower bearing into the cap with tang engaged. Position each rod onto its journal and install the cap in the correct orientation.
11. 11

    Torque connecting rod bolts
    Install and torque all 16 connecting rod bolts (2 per cylinder, 8 cylinders). Torque in two progressive steps: first to 15 ft-lb, then to the final spec of 19-24 ft-lb. Torque in a criss-cross pattern (tighten one bolt, then its pair). Torque in a criss-cross pattern (tighten one bolt, then its pair). After torquing, verify each rod cap is seated flush against the rod with no gap. Check rod side clearance on the crankshaft journal using a feeler gauge - clearance should be 0.010"-0.020" per rod. Rotate the crankshaft two complete revolutions by hand to verify smooth rotation with no binding or tight spots. Verified detail (The final torque spec of 45 ft-lb appears high for 1972 Ford 302 connecting rod bolts. Factory specification is typically 40-45 ft-lb range, but most sources specify 40 ft-lb or 19-24 ft-lb followed by a 40-degree turn for later models. 45 ft-lb may be excessive for the original bolts.): Torque in three progressive steps: first to 15 ft-lb, then to 25 ft-lb, and finally to 40 ft-lb.
12. 12

    Reinstall oil pump pickup tube
    Clean the oil pump pickup tube mounting surface and bolt holes. Position the pickup tube and screen assembly onto the main bearing cap and install the 2 mounting bolts. Torque bolts to 18.0 lb-ft (25.0 Nm). Verify the pickup screen is positioned 1/4" to 3/8" from the bottom of the oil pan when pan is installed (measure before final pan installation).
13. 13

    Clean and prepare oil pan
    Remove all old gasket material from the oil pan and engine block mating surfaces using a gasket scraper. Clean surfaces thoroughly with solvent and wipe dry. Inspect the oil pan for cracks or damage to the mounting flange. If using a cork/rubber gasket, trial-fit the gasket to verify proper alignment. If using RTV silicone, ensure surfaces are completely clean and oil-free.
14. 14

    Install oil pan
    Apply a thin bead of RTV silicone to the front and rear main seal junctions on the engine block (where the timing cover and rear main cap meet the block). Position the new oil pan gasket or apply a 1/4" bead of RTV silicone to the oil pan mounting flange (check gasket manufacturer recommendations). Carefully raise the oil pan into position and install all 18 bolts finger-tight. Starting from the center and working outward in a spiral pattern, torque all pan bolts to 10 ft-lb. Allow RTV to cure for the time specified by the manufacturer (typically 1 hour minimum) before adding oil.
15. 15

    Install new oil filter and refill engine oil
    Install a new oil filter after pre-filling it with clean engine oil and lubricating the gasket. Install and torque the oil pan drain plug with a new gasket to 15-18 ft-lb. Refill the engine with 5 quarts of 10W-30 or 10W-40 conventional engine oil. Reconnect the negative battery cable. Verified detail (Oil pan drain plug torque specification for 1972 Ford F-100 302ci V8): 26.0 lb-ft (35.0 Nm)

Reassembly

1. If engine was removed from vehicle, reinstall engine using engine hoist and reconnect all mounts, wiring, hoses, and exhaust components
2. If engine remained in vehicle, reinstall any crossmembers, exhaust components, or accessories removed for oil pan access
3. Double-check all fasteners are torqued to specification
4. Verify oil level on dipstick after initial fill

Verification

• Before starting engine, rotate crankshaft by hand for 2 complete revolutions to verify smooth operation with no binding
• Start engine and verify oil pressure reaches normal operating pressure (40-60 psi at 2000 RPM) within 10 seconds
• Check for oil leaks around oil pan gasket and drain plug while engine is running
• Listen for any abnormal engine noises such as knocking or ticking that could indicate bearing problems
• Allow engine to reach operating temperature and verify oil pressure remains stable
• After initial 20-minute run time, shut down engine, allow to cool for 10 minutes, and recheck oil level - add as necessary
• After 500 miles, change oil and filter, then inspect oil for metal particles on magnetic drain plug that could indicate bearing wear

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