Installation of connecting rod bearing inserts

Installation of connecting rod bearing inserts

During reassembly of the big-end bearing inserts the parts must be thoroughly cleaned and then to reassemble proceed as follows:

1. Ensure the bearing half to connecting rod surfaces are perfectly smooth and free of score marks. Under no circumstances may the bearing surface be reworked.
2. Check that the bearing half inserts are properly seated, with the locating lugs fitting into their slots: this is essential to obtain correct bearing clearance.
3. As the circumference of the bearing half is greater than the seats in connecting rod and cap the bearing must be fitted so that the projection at each end of the bearing half is equal.
4. Thoroughly lubricate all parts and tighten the end cap nuts to a torque wrench setting of 23.9 lb ft.

Little end bushing

The small end bush must be a firm fitting in the connecting rod and show no signs of deep scoring, scuffing, ovality or excessive wear.

Should it be considered necessary, the bush may be reamed using a Fiat expanding reamer U.0307 so that the bush internal diameter permits an oversize piston pin to be fitted with a clearance of .00020 to .00063 inch.

To fit a replacement bush proceed as follows:

1. Firmly hold the connecting rod between soft faces in a vice in such a way that it will not bend when working on the small-end and using a suitably sized drift, remove the old bush.
2. Use Fiat tool A.60155 or a suitably sized drift and carefully install the new bush which must be an interference fit of between .0011 to .0036 inch.
3. A small slot must be cut in the bush to correspond with the groove machined at the top of the connecting rod so ensuring good lubrication between the bush and piston pin.

4. Using an expanding reamer or Fiat reamer U.0307 ease

out the internal diameter of the bush to between .7874 to .7876 inch so that a standard piston may be fitted.

Piston-connecting rod assembly

To assemble the piston to the connecting rod fit the connecting rod to the piston so that the cylinder identification number which is stamped on the connecting rod stem and cap faces the expansion slot side in the piston as shown in FIG 1:32.

Lubricate the piston with engine oil, compress the piston rings into their grooves and insert the piston connecting rod assembly into the cylinder barrel with the identification numbers facing to the side opposite to the camshaft as shown in FIG 1:32.

If one or both connecting rods have been renewed the new connecting rod cap and body must be stamped with the cylinder identification number. The figures should be stamped as shown in FIG 1:32.

Upon reassembly the connecting rod cap nuts must be tightened to a torque wrench setting of 23.9 lb ft.