blue printing is basically taking measurement, dimension and clearance.this measurement used to determine serviceable level and to monitor engine components within specification
precision tools required are telescopic bore gauge, 2" and 3"micrometer and vernier caliper
before measuring bore of big end rod, ensure the rod caps are torqued. and dimensions is measured at several point to check roundness. the roundness check actually must be done using dial gauge but difficult to get one and expensive.
for those who suffer the rod bearing failure, this inspection is mandatory. normally con rod bearing failure may result sign of burn or discoloration around the big end.most probably caused by metal to metal contact. so what you need to do? if the burn sign not so severe than try using sand paper to wipe it off.if the color doesn't go off, change the rod. if it can be wiped off than continue with measuring big end and check for roundness. to play safe roundness limit should within 0.0002".
checking dimension of crank journals = 1.9678 - 1.9685"
rod/pin journal = 1.7709-1.7717".
plastic gauge thread can get at 30 ringgit
next is put the plastic gauge on the installed crank, and install the crank cap and torque.
than remove the crank cap and see how much the thread being press. measure on widest thread as below show 0.002". it is represent how much clearance between crank and bearing.
pin journal i got 0.0015 which more on tighter side.
it is a vital process in building race engine, do it right for the first time..so than u don't have to disassemble the engine again.
