Engine block

Look for general damage and cracks, possibly caused by frozen coolant. Check the waterways for excessive corrosion. Place a straight-edge across the deck and check for high spots with thin feeler gauges, especially where the studs are screwed in.

Bearing ovality

Refit all the main bearing caps without their shells. Use a bore gauge at various points around each circumference to see if the caps have been hammered oval. Moderate ovality can be corrected by grinding and then honing.

Bores

Looking from the water-pump end, the bores’ thrust side will be on the left. It’s likely you’ll feel a ridge in the area that corresponds with the top piston ring at top dead centre. Inspect all the bores all-round for pitting, water damage and scoring.

Measuring bore wear

The bore will be unworn at its base, with maximum wear just below the ridge at the top. Lock a bore gauge at the bottom of the bore. Move it to the top and measure the gap with feeler gauges. Measure in-line with the crank and at 90° to it.

Pistons and rings

Grasp the con-rod and piston and apply opposing force to check for wear in the little-end bush and gudgeon pin. Use feeler gauges to measure between the rings and the grooves. Try fitting a few rings to the base of a bore and measure the ring gap.

Piston wear

Check for cracks, damage and wear/scoring at 90° to the gudgeon pin. Insert into the bore and use feelers to measure the gap between the skirt and the bottom of the bore 90° to the gudgeon pin. Invert and measure the gap at the crown.

Good to go again?

Significant bore scoring or pitting dictates a rebore, as does a defined lip at the top (which also signifies it’s worn beyond tolerance). If the bores and pistons are in good condition and wear is within tolerance, a hone and new piston rings may be viable.

Crankshaft

Inspect the journals for putting and scoring. Run your fingernail across the surface of each to feel for ridging. All this dictates a regrind. Suspend the crank from a flywheel or pulley bolt and tap a web. It should ring. If it doesn’t, it may be cracked.

Crank journals

These wear oval, corresponding to the highest piston load just past TDC. Use a micrometer to take readings at this point and at 90° to it. Ovality means a regrind. If the journals miraculously pass all tests, you can just get them polished.

Bearing shells

You’ll replace these as a matter of course, but inspection can tell you interesting things: if the surface has worn off, that’s normal high mileage; wear on one side indicates an unevenly-worn journal; scoring indicates dirty oil or an oil supply issue.

Camshaft

Check the journals for damage and scoring. Very closely inspect the lobes for wear, pitting and imperfections in the surface hardening. Measure the journals and lobes with a micrometer and compare the sizes with those specified in the manual.

Camshaft bearings

Inspect for significant scoring or surface wear, particularly at the bottom – both of which signal that they need to be replaced. Check the camshaft thrust plate, too. Replace if the surface is worn or if camshaft end-float was excessive.

Cam followers

Look at the sides of the followers for discolouration and scratching. Scrutinise the surface hardening on the bases: any pitting, obvious lines or wear marks signify the need for new ones. Pushrods with ‘nippling’, like these, need replacing.

Timing chain and sprockets

Hold one end of the timing chain and see how much it sags over its length. If it deflects by over 8mm, replace it. Check the teeth of the sprockets to see if they’re polished shiny or ‘hooked’ in profile. Check the tensioner pad for excessive wear.

Flywheel

Wash with soapy water or brake cleaner. Remove any corrosion and inspect the friction face for scoring or cracks. The flywheel face can be re-machined. Check the teeth of the ring-gear for chips, breakage or excessive wear. It’s replaceable.

Oil pump

Make a visual inspection of the cover plate. It’s common for there to be radial scoring, but this can usually be removed by refacing using fine wet-and-dry paper on a flat piece of glass. Use feeler gauges to check every lobe in the two positions shown above. Insert a feeler gauge between the outer rotor and the body. Finally, put a straight edge across the top of the pump and check the clearance between it and the rotors. Compare the figures to the specifications in your workshop manual.

Cylinderhead face

Clean off the residue of the old head gasket and inspect the mating face for damage and pitting. Use a straight-edge to look for high and low spots. Lay the mating face on a perfectly flat surface – a sheet of glass is ideal – to check for warping.

Crack-testing the head

Even though the cylinderhead is cast iron, it’s still prone to cracking. It’s worth investing in a crack detection kit (£20) which comprises three aerosols: a cleaner, a penetrant dye and a developing powder. Before getting down to business, clean carbon deposits from the combustion chambers with a rotary wire brush and clean the outside of the head, especially around the spark plug holes. Follow the kit’s directions to hunt for cracks in the combustion chambers and on the outside of the head.

Valves

The valves can wear and fatigue where they contact the rockers and the heads can crack or burn. Inspect the sealing face of each valve for pitting, concavity and signs that the valve has been refaced previously, resulting in a thin or knife-edged head.

Valve stems and guides

If there’s any appreciable visual wear to the valves or guides, replace both. They’re cheap. Waggling the valves in the guides at 90° to the rocker shaft will expose excessive play. Measure the guides and stems if you want to be scientific.

Valve seats

The seats will need re-cutting as a matter of course if you’re replacing the valves and guides. Now’s a good time to fit unleaded valve seats, too. If you’re reusing everything, check the seats for pitting, burning or general rounding of the face.

Rockers

Strip the rocker shaft. Clean the parts, keeping them in order. If there’s any significant wear to the shaft of the rocker bearings, replace them. Slight wear on the rocker arms’ pads can be ground off by the machine shop if everything else is OK.

Valve springs

If the valve springs vary significantly in length, replace the whole set. If they’re uniform length and appear to be in good condition, measure their free length and compare it to the figure stated in your manual. New springs are only £2 each.

Bits and pieces

Check all the engine’s other large bits before writing your shopping list. Some crank pulleys have a vibration damper – make sure the rubber section is in good condition. Inspect pressed steel covers for damage and the distributor drive gear for wear.