Chapter 13 - Reconditioning engine blocks Topics to be covered Line honing or boring Honing cylinders for overhaul Boring and honing oversize Installing sleeves Reconditioning connecting rods Preparing piston and rod assemblies Grinding and polishing crankshafts Grinding flywheels Overhauling oil pumps Copyright 2003 Gary Lewis – Dave Capitolo

Reconditioning engine blocks Line honing and boring Purpose Advantages of line boring Advantages of line honing Procedure Changes crankshaft centerline

Reconditioning engine blocks Reconditioning cylinders Measuring wear Overhaul limits for taper & out of round Honing for overhauls If ring ridge remains… Add fig 13-1, explain old practice of re-grooving top groove or resizing rod housing bore

Reconditioning engine blocks Reconditioning cylinders for oversize pistons Boring and honing cylinders oversize Boring machine vs. boring bar Common sizes of oversize pistons Bore cylinders .003” to .005” under final size Hone to final size and surface finish

Reconditioning engine blocks Reconditioning cylinders for oversize pistons Honing cylinders oversize Cylinder alignment stays original Rough hone & leave .002” to .003” Finish hone to size and surface finish Stone selection

Reconditioning engine blocks Surface finishes for cylinders RMS, AA, & RA Range is 15 to 40 micro-inches Crosshatch pattern Chrome & cast iron rings = 25AA micro-inches Moly rings = 15AA micro-inches

Reconditioning engine blocks Dry sleeves Purpose Repair cracks or damage Restore bore to standard diameter Strength comparable to original Sizes available 3/32”, used for standard bore 1/8”, used for +.030” & up

Reconditioning engine blocks Dry sleeves Setting the boring bar Measure sleeve in 6 spots Average measurements .0005” to .001” press for each inch of bore 3/16” step at bottom of cylinder

Reconditioning engine blocks Dry sleeves Preparation Lightly deburr top & bottom of cylinder Chamfer bottom of sleeve Clean sleeve Installing sleeves Hammer & driver Chill sleeve & heat block Hydraulic press

Reconditioning engine blocks Dry sleeves Finishing the sleeve Trim top with boring bar and file/surface Bore ID, and leave .003” to .005” to hone

Reconditioning engine blocks Piston rings Stresses on rings Do pistons ever stop while the engine is running? Long stroke & high RPM High compression

Reconditioning engine blocks Piston rings Oil control rings Wipe excess oil from cylinder walls Excess oil is returned through rings & pistons Rails conform to shape of cylinder Expanders are required for thin rails

Reconditioning engine blocks Piston rings Compression rings Top 2 grooves 5/64” & 1.5mm are standard sizes 1/16” rings for performance .040” rings with “gas ported pistons” 2nd ring is oil scraper Top ring must seal to protect other rings from gas

Reconditioning engine blocks Piston rings Ring material & coating Compression rings are iron or ductile iron Oil control rails are chrome plated steel Iron oxide used to resist scuffing on iron rings Molybdenum used to improve scuff resistance Chromium plating for resistance to embedding

Reconditioning engine blocks Piston rings More ring materials Carbon steel Stainless steel Tool steel More coatings Chromium Nitride, Titanium Nitride Diamondlike Carbon

Reconditioning engine blocks Piston rings Ring assembly Oil control expander lined up with center of pin Oil control rails 2” either side Bottom compression ring lined up at end of pin Top ring lined up at opposite end of pin Watch for overlapping expanders Watch for proper end gap offset

Reconditioning engine blocks Connecting Rods Pin fit for press-fit piston pins Can be checked by feel .001” press fit in rod .0005” clearance in piston pin bores Replace pistons, pins, or oversize pins if needed

Reconditioning engine blocks Connecting Rods Pin fit for full-floating piston pins Can be disassembled and gauged .0004” clearance in rod bores .0002” clearance in piston pin bores

Reconditioning engine blocks Connecting Rods Measuring pin fits Two pins used to set gauge Measure rod bore Measure piston pin bore

Reconditioning engine blocks Connecting Rods Replacing bushings Bushings are pressed into small end of rod Line up oil hole/drill if not present Expand bushing into bore and face off excess bushing

Reconditioning engine blocks Connecting Rods Replacing bushings Rough hone to within .002” of finished size Finish hone to size with finishing stones

Reconditioning engine blocks Connecting Rods Sizing with a boring machine Corrects for bend and twist Center-to-center can be equalized

Reconditioning engine blocks Connecting Rods Resizing housing bores To restore bearing crush To restore proper oil clearance

Reconditioning engine blocks Connecting Rods Resizing housing bores Stretched housing bores are common Should be resized to within .0003” roundness

Reconditioning engine blocks Connecting Rods Procedure for resizing rods Remove rod bolts Grind .002” from both cap and rod, or until clean Keep grinding equal for each set of rods

Reconditioning engine blocks Connecting Rods Preparation for resizing rods Clean and reassemble – May need new hardware Torque to specs Set gauge to specs Hone to size

Reconditioning engine blocks Connecting Rods Honing housing bores With power-stroking attachment Set RPM and stroke rate RPM, stroke rate, & overstroke help stone life

Reconditioning engine blocks Connecting Rods Honing housing bores Without attachment, hone two rods at a time Reverse position of rods for quality

Reconditioning engine blocks Connecting Rods Honing housing bores with diamond tools Minimal abrasive wear Better size control Methods similar to abrasive stones

Reconditioning engine blocks Connecting Rods Center-to-center distances Keep length within .003” Shortest rod becomes standard Recut rod caps that are > .003” longer Excessive honing may damage bearing grooves

Reconditioning engine blocks Connecting Rods More reconditioning Deburr sides of rods with file Rechamfering may be required

Reconditioning engine blocks Connecting Rods Assembling piston & rod assemblies Check position of pistons & rods in the engine

Reconditioning engine blocks Connecting Rods Assembling full floating assemblies Clean, oil, and assemble Inspect/replace locks

Reconditioning engine blocks Connecting Rods Assembling oscillating assemblies Assemble with press in one direction or . . . Use rod heater - Heat small end to 425°F Center pin into piston & rod

Reconditioning engine blocks Connecting Rods Checking rod alignment Bend and twist

Reconditioning engine blocks Connecting Rods Correcting press-fit assemblies Assemble piston & rod first Check & correct bend first

Reconditioning engine blocks Connecting Rods Correcting press-fit assemblies Turn piston to one side Check & correct twist

Reconditioning engine blocks Connecting Rods Correcting full floating assemblies Check bend, then twist using piston pin

Reconditioning engine blocks Connecting Rods Checking rod offset Measure difference between each side of rod and face of aligner

Reconditioning engine blocks Flywheels Used on standard transmission Used with clutch assembly to couple & uncouple engine and transmission

Reconditioning engine blocks Flywheels Resurfacing To restore flatness To remove heat checking To restore parallelism

Reconditioning engine blocks Flywheels Set up Magna-flux back of flywheel Parallelism should be less than .005” TIR

Reconditioning engine blocks Flywheels Set up Remove dowel pins as needed Deburr & index on crankshaft surface Grind & spark out for flatness

Reconditioning engine blocks Crankshaft fitting Housing bores Diameters within tolerance Round within .0003” Bearings Specified thickness Installed to specified clearance Crankshaft Diameters within tolerance Round within .0005” Straight within ½ of oil clearance Surface finish 10Ra or better

Reconditioning engine blocks Crankshafts Inspection Clean Check for cracks (wet mag) Size & out of round Straightness

Reconditioning engine blocks Crankshafts If ground while bent, crankshafts . . . Become out of balance Cause stroke length differences Cause alignment problems

Reconditioning engine blocks Crankshafts Welding crankshafts To keep undersize to a minimum Gas shield method Welding is covered by Argon or CO2 Submerged arc method Welding is covered by flux powder

Reconditioning engine blocks Crankshafts Welding crankshafts Journals are built up Then ground to size

Reconditioning engine blocks Crankshafts If fillets were welded Crank is straightened after welding Roughed to within .030” Re-straightened Finish grind, and then grind mains last

Reconditioning engine blocks Crankshafts Stress relieving after welding several journals Heated to 900°F – 1100°F Soak for a few hours Shot blast after to remove scaling

Reconditioning engine blocks Crankshaft hardening Nitriding Heat treatment for crankshaft hardness Salt bath (Tuff-Triding) or gas atmosphere Nitriding causes journal diameters to grow

Reconditioning engine blocks Crankshaft hardening Chrome plating Journals are ground .006” undersize Plate with hard chrome Dry at 350°F & slowly grind to size

Reconditioning engine blocks Crankshaft grinding Common undersizes .010”, .020”, & .030” for domestic crankshafts .25mm, .50mm, & .75mm for import crankshafts

Reconditioning engine blocks Crankshaft grinding Crankshaft must be within limits of . . . Taper, roundness, size, fillet radius, stroke length, & surface finish

Reconditioning engine blocks Crankshaft grinding Set up In chucks or between centers

Reconditioning engine blocks Crankshaft grinding Set up Grinding wheel is dressed with specified radius

Reconditioning engine blocks Crankshaft grinding Set up Crankshaft is offset to ½ the stroke length Other journals are indexed Mains are ground on center of rotation Positioning is done from seal surface & gear/sprocket surface

Reconditioning engine blocks Oil pumps Overhauling End clearance limit is .003” for both pumps Sand pump body to reduce clearance Gear teeth to body clearance limit is .005” Scrap gear type pumps if scored

Reconditioning engine blocks Oil pumps Overhauling Clearance limit between rotors is .014” Clearance limit for outer rotor to body is .010”