Engine Notes

UNDERSIZE CRANKSHAFT CAUTION - Some.010" undersize crankshafts were used in production on 1968-69 460 CID engines. Engines can be identified by letter "M" and/or "P" (main or rod journal) stamped on right front of cylinder block near the engine date code stamp. Backs of the bearings are stamped ".010 U.S.". Check for engine stamping or bearing marks before ordering or procuring new rod or main bearings.
NEW REAR MAIN OIL SEAL - A new type split-lip rear main oil seal is now available for 1968-69 429 and 460 CID engines. New seal can be installed without removal of crankshaft from engine and does not require any special tools for installation. Order part No. C9AZ-6701-A.
CAUTION: Before installing new type oil seal it is mandatory that oil seal pin be removed from rear main bearing cap and discarded.
FRONT MAIN BEARING KNOCK - Some 429 and 460 CID engines built in late 1968, and 1969 may have a pronounced knock at approximately 800-1200 RPM under slight engine load, or at vehicle speeds up to approximately 25 MPH. The intensity of the knock may sometimes be decreased by lessening the accessory drive belt tension. Knock may not be audible until engine temperatures are stabilized, and may then progressively increase.
It is recommended that engines exhibiting this knock be select fitted with new main bearings that will provide an operating clearance of.0005-.0015". It is permissable to use half of a.002" U.S. bearing in combination with a standard size or.001" U.S. insert. When a combination of inserts is used the undersize bearing half should be installed into the upper, or rod, position.

CAUTION: Do not file or lap bearing caps, or use shims behind bearing inserts.
PUSH ROD CAUTION: 429" Cobra Jet and Super Cobra Jet are equipped with, and require a special hardened push rod. These hardened push rods are identified by a purple band, one inch from each end. They may be further identified by a file test for hardness in the center portion. A hardened push rod should not mark, or show only a slight scratch. Non-hardened push rods are easily marked. Under no circumstances are standard push rods to be used in these engines.
1969-77 429" & 460" ENGINE COOLANT LEAKS: If coolant leaks after replacement of water pump or engine front cover, it may be due to improper installation of water pump gasket. Gaskets without tabs must be installed between water pump housing and water pump cover. Gaskets installed with tabs must be installed between water pump cover and engine front cover.
1969-77 ALL ENGINES NEW VALVE GUIDE REPAIR BUSHINGS: New cylinder head valve guide repair bushings are available for vehicles exhibiting excessive valve guide wear to the extent that over sized valves cannot be used.
1969-70 VALVE STEM TIP WEAR: If valve stem tip wear is indicated, a new lighter load valve spring should be installed when the valve is replaced. The color code for the new valve spring is gold.
429" COBRA JET: Later 1970 production engines are equipped with new positive stop valve rocker arm studs to provide fixed method of adjusting hydraulic tappets. When installing new type stud, screw stud into head until shoulder on stud contacts cylinder head, then torque 75-85 Ft. Lbs. Use.060" U/S or.060" O/S push rod if standard push rod does not provide proper hydraulic tappet clearance.