short block

the short block is the main part of the engine. everything is connected to it. engine block is usually made of cast iron or aluminium.the block has been cast and machined to the perfect size and shape for the cylinders to reduce engine wear and increase its efficiency. the block contains many passages for oil which lubricates different parts and for water to cool the engine down.

dis assembly of the short block
place all bolts and parts in a labeled container

1. drain all oil from engine
2. remove cylinder head and sump
3. remove oil pick up and filter
4. remove big end bolts
5. remove big end and take out pistons (stamp the pistons and big end with the cylinder number so that you know which piston goes in which cylinder and which way the piston is facing)
6. remove piston rings and oil scarper rings (place with correct piston)
7. remove big end bearings and place with correct piston
8. remove the crankshaft holders
9. remove crankshaft and thrust bearings

short block tests

pistons:
 piston skirt size: using a micrometer measure the piston skirt and compare with manufacturers specifications
connecting rod twist/bend: visually inspect the con rods to see if they are bend or twisted. if they are they may need to be replaced
piston ring end gap: compress piston ring inside cylinder and press it down using the piston. using a feeler gauge measure the gap and compare to manufacturers specifications. repeat for all piston rings (if you have your engine apart you may want to replace the piston rings because it will normally be along time before you will have the engine apart and replacing piston rings can be very costly if you have to do it later on down the track)
crankshaft:
 testing crankshaft journals: measure the big end journals in two places and record findings then rotate the crankshaft 90degrees and measure the same two places and compare with manufacturers specifications for taper and ovality
crankshaft deflection: place the crankshaft on v blocks and use a dti gauge to measure runout on the main bearings and compare to manufacturers specifications
block:
cylinder bore: measure the cylinder bore at three different heights and record findings, twist the bore gauge 90degrees and measure the same three heights compare these findings to the manufacturers specifications for taper and ovality
warping in the block: to measure this we use a straight edge placed on different sections of the block and used a light to see if there was any gap. if it looked like there was a gap we used a feeler gauge to test the measurements of the gap. if the measurements were larger than those specified by the manufacturer then you will need to have the block skimmed or replaced.

re assembly of the short block

1. place the crankshaft and thrust bearings in the right places
2. place the main bearing holders on and screw bolts finger tight
3. put piston rings back on the pistons
4. place piston 1 in cylinder 1 and using a piston ring compressor push the piston into place (make sure the big end bearing is in the right place before putting the piston in
5. screw the bolts holding the piston in finger tight
6. do the same for all pistons
7. rotate the crankshaft to make sure everything spins freely (if it does not spin freely then you will need to source the problem. it could be a piston that does not fit properly or that something is in the wrong pace)
8. using a torque wrench tighten up the main bearings to the manufacturers specifications
9.  rotate the crankshaft to make sure everything spins freely
10.  using a torque wrench tighten up the big end bearings to the manufacturers specifications
11.  rotate the crankshaft to make sure everything spins freely
12. attach the oil pick up and filter
13. put the sump and cylinder head back on
14. time the engine.
15. rotate the engine so cylinder 1 is on the combustion stroke at top dead center
16. make sure the valves are in the correct place for cylinder 1 top dead center firing
17. put cambelt on
18. tighten up the tensioner so the cambelt is on tight
19. adjust the distributor so that it in cylinder 1 firing