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…
Add fig 13-1, explain old practice of re-grooving top groove or resizing rod housing bore

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

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

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

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

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

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

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

57. 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

58. 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

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