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Chapter 13 - Reconditioning engine blocks

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.

Samuel
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Chapter 13 - Reconditioning engine blocks

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  1. 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

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

  3. Reconditioning engine blocks • Reconditioning cylinders • Measuring wear • Overhaul limits for taper & out of round • Honing for overhauls • If ring ridge remains…

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

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

  12. 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

  13. 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

  14. 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

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

  16. 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

  17. 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

  18. 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

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

  20. 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

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

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

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

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

  25. 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

  26. 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

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

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

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

  30. 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

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

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

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

  34. 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

  35. Reconditioning engine blocks • Connecting Rods Checking rod alignment • Bend and twist

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

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

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

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

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

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

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

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

  44. 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

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

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

  47. 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

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

  49. 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

  50. 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

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