Block inspection Some visual checks Cylinder cracking Scuffing & scoring Damaged fasteners Housing bores Copyright 2003 Gary Lewis – Dave Capitolo

Block inspection Crack detection Bolt holes Main bearing webs Core plug holes Intake valley

Block inspection Cylinder wear Maximum wear 90 across piston pin, at top of cyl Head bolts & coolant circulation distort cylinder Taper – difference between bottom and most worn Actual wear exceeds measured Taper limit -.008”

Block inspection Piston clearance Don’t confuse taper with clearance Minimum cylinder diameter – max piston diameter

Block inspection Checking pistons Ring groove wear =.003” to.006” or 2 times new

Block inspection Checking pistons Worn or collapsed piston skirts Measure 90º across piston pin at top & bottom Knurling – If clearance exceeds specs up to.002”

Block inspection Checking pistons Collapsed piston – When piston loses cam shape Measure 45º across piston pin Leads to piston ‘slap’

Block inspection Checking piston pin clearance Oscillating pins are checked by feel Full floating pins can be disassembled & measured.0002” clearance in pistons.0004” clearance in rods

Block inspection Checking block flatness Scrape deck surface Deburr deck surface.004” Go/No-go Consider head flatness

Block inspection Measuring main housing bores Main caps stretch from load Check block for warpage

Block inspection Measuring main housing bores Check bearing wear Bent crankshaft – Wear all around bearing Warped crankcase – Wear on one side only Concentricity of main seal

Block inspection Measuring main housing bores Clean & deburr parting faces Check fit in saddle Torque & measure with dial bore gauge

Block inspection Checking the crankshaft Scoring Taper & out of round Taper exceeding.0005” may allow oil to escape

Block inspection Crankshaft straightness Use V-blocks or end main bearings Should not exceed ½ main clearance

Block inspection Crankshaft cracks “Ring” crankshaft Wet Magnaflux crankshaft

Block inspection Connecting rod bores Stretch comes from engine load High engine speeds tend to stretch bores Small displacement engines use large rod bores Caps may spring outward on disassembly Bend & twist should be within.001” per 6” of rod. Cause wear patterns on pistons & bearings

Block inspection Connecting rod bores Special gauges are used for housing bores Out of round & size must be checked

Block inspection Connecting rod failures Begin with bearing failure Bearing shell wedges under the other Rod bolt breaks Rod & cap break