Figure 6-36. Measuring Ring End Gap

rod bearing calf and crankshaft journal (Figure 6-37).

Install connecting rod bearing cap and tighten nuts to 39

foot pounds torque. Try to rotate crankshaft one full turn

by hand. If drag is felt, the clearance is correct. If the (

crankshaft turns freely, it will be necessary to measure

crankshaft journal for taper or out of round. If taper or

out of round exceeds 0.0015 inch, replace crankshaft.

i. Installation.

(1) It is important to remove glaze on cylinder

bore to assure quick seating of piston rings.

(a) Cover crankshaft journals with clean cloth to

prevent dirt and abrasives, from getting on crankshaft.

(b) Surface hone cylinder bores with glaze breaker

to break glaze and produce dull finish in bore. Clean

glaze breaker between use in each cylinder bore to

reduce amount of loose abrasives released in bore.

Figure 6-36. Measuring Ring End Gap

rag, to pick up any abrasive that might be left in bore.

bore (use a piston to straighten the ring in the cylinder)

Follow this with clean cloth to assure that walls are

measure the gap between the ring ends with a feeler

clean.

gauge (Figure 6-36). The ring gap for all rings is 0.015

(2) Install oil rings and compression rings on

to 0.020 inch. If the gap is less than specified, remove

piston with ring expander tool Start with the lowest ring

the ring and dress end with a fine-cut mill file until correct

first. Make sure that tapered side of compression ring is

clearance is obtained.

up. Make sure that the ring gaps are equally spaced

(3) Measure side clearance of piston rings in

about circumference of the piston, not in vertical

the grooves with feeler gauge. Gap should be 0.0035 to

alignment.

0.005 inch for top compression ring. Scraper and oil ring

(3) Oil cylinder wall and generously coat

gap is 0.0015 to 0.003 inch. If clearance is less than

piston and rings with OE (lubricating oil, internal

specifications, remove ring from piston and rub the ring

combustion engine).

lightly on piece of fine emery cloth (all on flat surface)

(4) Install ring compressor on piston and

until proper clearance is obtained.

compress rings into grooves. Tap compressor lightly

g. Connecting rod alignment.

around circumference of piston to allow rings to seat

(1) Install piston pin in connecting rod and

evenly in grooves.

place connecting rod, with sleeve bearings, on aligning

fixture. Install connecting rod bearing cap on connecting

rod.

(2) Pin should touch measuring bar on

aligning fixture at both ends. Straighten bent or twisted

connecting rods. Maximum bend or twist may not

exceed 0.inch over 4 inch spread of length of the

connecting rod.

h. Connecting rod bearing installation.

(1) Connecting rod bearings that are scored,

burned, or damaged must be replaced by new ones.

Replacement bearings require no reaming or fitting.

(2) Install the piston with connecting rod and

with upper half of connecting rod bearing installed, but

without piston rings, in the cylinder bore. Coat a piece of

0.002 inch feeler stock, approximately 1/2 inch wide and

1 inch

Figure 6-37. Measuring Rod Bearing Clearance

108