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1. Block Prep & Inspection
Visual & Structural Checks
Check for cracks:
Main webs (especially #2–#4)
Lifter valley
Side‑oiler gallery (if applicable)
Rear main seal area
Verify cross‑bolt bosses are intact and not ovaled
Confirm all oil gallery plugs are removable
Check for core shift (especially early C3 blocks)
Sonic Map (Required for any overbore)
Target minimum wall thickness:
Safe street: 0.120"
Safe race: 0.100"
Thrust side should be ≥ 0.150" before boring
Record 12‑point map per cylinder
🔵 2. Cylinder Bores
Dimensions
Nominal: 4.2328"
Max NHRA: 4.312"
Out‑of‑round: ≤ 0.0005"
Taper: ≤ 0.0007"
Finish
RA: 15–25 µin for moly rings
Plateau hone recommended
Chamfer top lightly for ring installation
🔵 3. Decking
Deck Height
Factory nominal: 10.170"
Blueprint target: 10.150" (common race cut)
Geometry
Parallelism: ≤ 0.0015"
Perpendicularity to crank: ≤ 0.001"
Notes
Keep decks equal side‑to‑side
Verify intake manifold alignment after decking
🔵 4. Main Bore & Webs
Main Bore
Diameter: 2.7495" – 2.7505"
Alignment: ≤ 0.0005"
Out‑of‑round: ≤ 0.0003"
Main Web Thickness
Center webs: 0.900" – 1.000"
Front/rear webs: 0.750" – 0.850"
Cross‑bolt boss width: 0.900" – 1.000"
Thrust Bearing
Width: 0.995" – 1.000"
Endplay: 0.005" – 0.009"
🔵 5. Cam Tunnel
Dimensions
Cam bore: 2.124" – 2.125"
Alignment: ≤ 0.001"
Centerline height: 5.430" ± 0.003"
Bearing Fit
Crush: 0.0015" – 0.0025"
Notes
FE cam tunnels are often misaligned — check before assembly
Side‑oiler blocks tend to be straighter due to thicker casting
🔵 6. Lifter Bores
Dimensions
Diameter: 0.8745" – 0.8755"
Out‑of‑round: ≤ 0.0005"
Geometry
Angle: 45° bank angle
Spacing: 1.810" center‑to‑center
Notes
FE lifter bores vary wildly — bushings recommended for race builds
Side‑oilers have more consistent oil feed
🔵 7. Rotating Assembly Clearances
Crankshaft
Main journals: 2.749" – 2.750"
Rod journals: 2.438" – 2.440"
Stroke: 3.784" ± 0.004"
Bearing Clearances
Mains: 0.0025" – 0.0030"
Rods: 0.0022" – 0.0028"
Piston‑to‑Wall
Forged: 0.0045" – 0.0055"
Cast (rare on 427): 0.0025" – 0.0030"
Ring End Gaps
Top: 0.018" – 0.022"
Second: 0.020" – 0.024"
Oil rails: ≥ 0.015"
🔵 8. Oil System (Side‑Oiler vs Top‑Oiler)
Passage Diameters
Main gallery (side‑oiler): 0.500" – 0.562"
Cam feeds: 0.312"
Lifter feeds: 0.250"
Pump inlet: 5/8"
Filter adapter: 0.500"
Routing
Side‑Oiler
Pump → Filter → Side gallery → Mains → Cam → Lifters
Best for high RPM
Less cam bearing starvation
Top‑Oiler
Pump → Filter → Cam → Mains → Lifters
More sensitive to cam bearing clearance
Holman‑Moody Mods
Enlarge pump inlet to 3/4"
Chamfer main feed intersections
Restrict rocker feeds to 0.060"
Open lifter gallery crossover slightly for stability
🔵 9. Rear Main Seal & Register
Seal diameter: 3.000"
Groove width: 0.375"
Cap register width: 0.625"
Perpendicularity: ≤ 0.001"
🔵 10. Cross‑Bolts
Bolt diameter: 7/16"
Boss spacing: 2.000" ± 0.010"
Perpendicularity: ≤ 0.0015"
Cap side‑register depth: 0.250"
🔵 11. Torque Specs (Critical)
Mains
1/2" bolts: 95–105 ft‑lb
Cross‑bolts: 40–45 ft‑lb
Rods
3/8" bolts: 45–50 ft‑lb
7/16" bolts (LeMans rods): 65–70 ft‑lb
Heads
Iron heads: 105–110 ft‑lb
Aluminum heads: 95–100 ft‑lb
Other
Rocker stands: 45–50 ft‑lb
Intake: 25 ft‑lb
Exhaust: 28–32 ft‑lb
🔵 12. Final Machinist Checklist
Block
[ ] Sonic map complete
[ ] Bore size & geometry verified
[ ] Deck height matched L/R
[ ] Main bore align‑honed
[ ] Cam tunnel checked
[ ] Lifter bores measured
[ ] Oil passages cleaned & brushed
[ ] Freeze plugs installed with sealant
[ ] Gallery plugs installed & staked
Rotating Assembly
[ ] Bearing clearances set
[ ] Thrust clearance set
[ ] Piston‑to‑wall verified
[ ] Ring gaps set
[ ] Rod side clearance checked
Oil System
[ ] Pump inlet matched
[ ] Filter adapter passages deburred
[ ] Restrictors installed (if racing)
[ ] Pickup clearance 1/4"–3/8"
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