Resurfacing Heads & Blocks To restore gasket sealing & flatness Surface damage from: Corrosion around water passages Combustion gases Improper handling Engine overheating Improper torque sequence Copyright 2003 Gary Lewis – Dave Capitolo

Resurfacing Heads & Blocks Surfacing complications OHV in-line engines Valve clearance with non-adjustable rockers Valve-to-piston clearance Possible detonation, higher compression ratios

Resurfacing Heads & Blocks Surfacing complications OHC in-line engines Possible detonation, higher compression ratios Retarded valve timing – About 1° per.020” Piston-to-valve clearance Install timing cover before surfacing

Resurfacing Heads & Blocks Surfacing complications OHV V-block engines Valve clearance with non-adjustable rockers Valve-to-piston clearance Possible detonation, higher compression ratios Intake manifold alignment - Oil consumption - Vacuum leaks

Resurfacing Heads & Blocks Compression ratio changes High vs. Low compression ratios Octane requirements increase with compression Emissions & power increase with compression Detonation chances increase with compression

Resurfacing Heads & Blocks Surfacing machines Sanding Quick Less precise Good for quick clean-up of exhaust manifolds Difficult to maintain precision

Resurfacing Heads & Blocks Surfacing machines Grinding Uses abrasive stones Can cut through hard material Good surface finish is possible Final passes are ‘sparked out’

Resurfacing Heads & Blocks Surfacing machines Grinding (cont.) For Aluminum... Take shallow cuts Dress stone often Use soap on stone

Resurfacing Heads & Blocks Surfacing machines Milling Carbide generally for Aluminum CBN generally for Iron With good setup, heavy cuts are possible Hard spots dull cutters

Resurfacing Heads & Blocks Surfacing machines MLS gasket preparation Surface finish – 20 AA micro-inches Light cuts with slow feed rates Sharp cutters with lubrication Dress stones often

Resurfacing Heads & Blocks Stock removal Generally as little as possible (.020” total) Specs may not be available When available, specs = min thickness or max removal Some composite gaskets compensate for.010” Stock removal may exceed measured warp

Resurfacing Heads & Blocks OHC head surfacing Chain driven engines need timing cover installed Top side can be surfaced for cam alignment Use shims to restore cam height

Resurfacing Heads & Blocks Diesel head surfacing Surface with pre-combustion chambers in place Chambers may be difficult to machine Measure valve recession on tear down Restore valve recession by grinding seats

Resurfacing Heads & Blocks Air cooled head surfacing Sealing surface is inside chamber Seal surface is machined Inside diameter of surface may be contoured Surface deck to restore seal depth

Resurfacing Heads & Blocks Resurfacing blocks To maintain parallelism to crankshaft Provide a better seal Match deck heights on V-blocks

Resurfacing Heads & Blocks Manifold alignment on V-blocks Correction for port alignment Correction for gasket crush

Resurfacing Heads & Blocks Manifold alignment on V-blocks Distributors can be shimmed to prevent intermediate shaft binding

Resurfacing Heads & Blocks Determining ratios Determine angle between cylinders Determine angle of cylinder head

Resurfacing Heads & Blocks Determining ratios For port alignment, surface... Intake side of head, or Intake side of manifold