Hot Rod Magazine, August 1955, 2nd page

Transverse, left, and longitudinal sections of Packard V8. Note large ports, excellent water jacketing around critical areas.

gasket seal. This little feature could and should be used by a few other manufacturers. This dimension also allows the bore diameters to be enlarged at a future date without scrapping the existing tooling. All that is required is a relatively simple and inexpensive change in the coring of the cylinders. Sufficient space in the underside of the block has been provided for a substantial increase in crankshaft stroke, when the need arises, without interference with the existing block casting or other parts. The overall length of the cylinder block is 27 3/4 inches. From all outward appearances, the block could be safely rebored to 4 1/8 inches with no particular danger from cylinder distortion or overheating; on Packard and Clipper "Custom" blocks, that is. The 3 13/16 inch bores of the Clipper "DeLuxe" and "Super" blocks, as well as those of the Hudson and Nash, could be bored to a maximum of 3 15/16 inches with reasonable safety.

Packard engineers went to considerable lengths to evaluate the relative merits of forged versus cast crankshafts. According to their findings, a steel casting provides a sufficiently high modulus of elasticity as well as material density to effect a lighter crankshaft without sacrifices in rigidity or stiffness. Also, a casting permits the counterweights to be more favorably disposed for balancing effectiveness, as well as coring of the crankpins to reduce the amount of unbalance and, consequently the size of the counterweights. The finished Packard V8 crank is a heat-treated alloyed steel casting that weighs 56 pounds. The five main bearing journals are ground to a

diameter of 2.500 inches and the crankpins are 2.250 inches in diameter. These dimensions are well within the realm of design conservatism shown elsewhere in the engine. With the 3 1/2 inch stroke, an overlap of 5/8 of an inch is obtained between the crankpins and adjacent main bearing journals, which materially contribute to the torsional stiffness of the crank. The total connecting rod effective bearing area is 52.8 square inches and the total main bearing effective area is 38.6 square inches. A non-bonded rubber harmonic balancer is placed at the nose of the crank and is effective in reducing the amplitude of torsional vibrations. The balancer is integral with the crankshaft pulley assembly. Fore-and-aft crankshaft thrust loads are taken by the flanged rear main bearing.

The main bearings are copper-lead, while connecting rod bearings are lead-babbitt, and both are of the steel-backed replaceable insert type. Both bearing materials are completely compatible with the heat-treated but unhardened steel crank. Each connecting rod has its own bearing that is locked in the rod and the crankshaft is drilled to oil each of the two bearings on the crankpins.

The healthy appearing connecting rods are drop forgings made from SAE 1041 steel. The beam is of "H" section design and the rods have a center-to-center length of 6 23/32 inches. Two specially formed high tensile steel bolts locate and secure the rod cap to the rod. A groove is machined at the juncture of rod and cap to provide lubrication from the rod bearings to the cylinder walls on the opposite bank. Balancing lugs form

integral parts of the rod assembly, one lug at each end. A bronze piston pin bushing is pressed into the small eye of the rod and is bored to give .0002 of an inch clearance between the bushing and the pin. The connecting rod assembly has undergone very severe testing at loads and speeds, far in excess of those encountered in any type of driving conditions. Each rod assembly weighs one pound 10 ounces.

Aluminum alloy "autothermic" pistons are used in which steel tension members control the amount and direction of piston expansion. The pistons "nest" about the crankshaft counterweights at the bottom of the stroke, which necessitates a "slipper" type skirt. Crown thickness of the flat-topped piston is .280 of an inch. Three ribs extend from the piston pin bosses to the crown for pin boss rigidity. The .980 of an inch diameter by 3 1/4 inch long piston pin is a full floating affair that is retained in the piston by snap rings and grooves in the pin bosses. The pin material is heat-treated SAE 1117 steel. The piston pin bores are offset 1/16 of an inch in the direction of the major thrust face. Pistons are tin plated to minimize "scuffing" during the initial break-in period. Piston weight is one pound six ounces.

Two compression rings and one oil ring are used, all of which are located above the piston pin. The alloy cast iron compression rings are 5/64 of an inch wide with a radial thickness of .200 of an inch and have tapered faces. The top ring is chrome plated to a thickness of from .004 to .007 of an inch for longer, life and freedom from the effects of high temperatures and corrosive gases.

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