1963 Corvette: Chevrolet Advance Information: Engine Crankcase Backfire

Subject:    Engine Crankcase Backfire
Model and Year: All 1963 Corvettes Except Fuel Injection
Source: Chevrolet Advance Information Letter
Bulletin Number: #AI-63-10
Date:   February 12, 1963

An accidental carburetor backfire during severe cold-weather starts, may result in a flame traveling down the air cleaner to crankcase vent fresh air supply tube, igniting the fumes in the crankcase.  In extreme cases, the resulting explosion may damage the oil pan and rocker covers.

A final production correction has not been determined at this time; however, installation of a flame arrestor screen to the inside of the air cleaner (as illustrated on the attached sheet) will prevent re-occurance of this condition.

FLAME ARRESTOR SCREEN INSTALLATION

Using 14 mesh galvanized screen, cut a circle approximately 1-1/2" in diameter and solder around outer edge of screen to prevent individual wires from being sucked into the engine.

Bend brake anchor pin washer Part No. 3710492, to fit contour of air cleaner.  Position washer and drill two (2) 5/32" diameter holes through washer and air cleaner base.  Place galvanized screen under washer and secure with two (2) #6 screws and nuts.

NOTE :  Ends of screws must be cut short and "peened" over nut to keep engine vibration from loosening screws, allowing them to be swallowed through the carburetor.