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Connecting Rods:
Connecting rods, #3927145 (1967), No. 3923282 (1968) and No. 3946841 (1969) are high-quality production parts with improved surfaces (shot-peened) between rod and cap. In addition, they are heat-treated to a higher hardness and magnaflux inspected to be sure they are free of flaws. All other rods should be magnafluxed before using. Connecting rod durability can be improved by performing the following operations: round all sharp edges on I-beam of rod and grind off excess flash where forging dies came together along sides of rod. It is not necessary to remove all this flash or polish the rod, but all grinding should be lengthwise of the rod and finish ground very smooth. Round all sharp edges around the rod bolt head and nut seats, and smooth out any nicks in the radius of the bolt and nut seats with a small grinder. Have entire rod, including bolt and nut seats, shot-peened. Have the big end of the rod carefully reconditioned on a Sunnen rod reconditioner. Install with new magnafluxed bolts and nuts. Torque 1967 or earlier rods with 11/32” bolts to 35-40 ft.-lb. Torque 1968-69 rods with 3/8” bolts to 45 ft.-lb. 1969 design connecting rods are sized on the wrist pin end for floating pins.

Premium forged pistons with floating pins were specified on heavy-duty 302s.

Pistons:
Smooth sharp edges of the domes. For installation of rods using pressed-in wrist pins it is necessary to heat the rod small end and install the pins quickly in a fixture. Most automotive machine shops are equipped to make the assembly. It is necessary to have at least .001” or preferably .0012” press fit between the wrist pins and the rods to ensure the pin will not loosen and move during running. For 1969 all 302’s are equipped with full floating pins using Spirolox pin retainers No. 3946848. Production and service wrist pins will have machined flat ends for use with floating pin retainers. If Tru-arcs pin retainers are used, install with square edge of retainer facing away from the end of the pin towards the cylinder wall. This sharp edge will tend to bite into the piston groove better and resist being pushed out. Make sure there are a few thousanths end play with the retainer installed. Run the production Moly groove-type piston rings for best blow-by control and minimum friction. Chevrolet piston production numbers for pressed and floating pin assembly are as follows:

Camshaft:
OK as is; use nylon tooth cam sprocket or high-quality aftermarket roller chain. The production Z-28 Camshaft is No. 3849346 with .455” lift and is to be hot lashed at .030” for both intake and exhaust valves. Optional camshaft No. 3927140 is a long duration .473” intake and .492” exhaust lift higher-performance cam and is not recommended for use on the street. It should be installed with No. 3927142 valve springs. Any dual valve spring that will provide 120 lb. load with valve closed and 300 lb. +/- 15 lbs. at .500” lift will work satisfactorily. Hot lash .022” inlet and .024” for exhaust valves. It is recommended that “Molykote”, or other molydisulfide-based EP lubricant should be used on camshaft lobes for proper break-in. In addition, valve lifters will be more compatible with the camshaft if you polish the contact surface with No. 600 grit paper before installing them. Good used lifters that still retain some crown or convex curvature across the bottom are very satisfactory.