Medium, Heavy Or Extra Heavy Duty Trucks With 330, 361 or 391 CID Engines

If piston scuffing and/or broken rings on the No. 1 piston are found in Ford Trucks with 330, 361 or 391 CID engines, the cause may be due to a timing cover bolt which is too long.

If you find a bolt with a flat head which is 3/8-16 x 3-1/2" with a washer, which is the third bolt from the bottom of the cover as shown in the sketch below, replace it with the correct bolt-a self-locking bolt 3/8-16 x 3-3/16" with six notches on the head.

FRONT COVER INSTALLATION

(P52)