Chevy Bellhousings

People commonly define Chevrolet Bellhousings by the Clutch size i.e. (10.5",11", or 12"). Flywheel Diameter (12.75" or 14") or number of teeth is more accurate because some 168 tooth flywheels are drilled with multiple bolt patterns and the aftermarket makes a 153 tooth flywheel that a 11" clutch and pressure plate will fit.

Chevrolet has always had just two sizes of flywheel Big (168 tooth 14" diameter) and Small (153 tooth 12.75" diameter) with the 153 tooth flywheel being introduced in 1963.

The early bells were cast iron with the aluminum bells being fazed in and eventually the only material for all factory bells.

With that said most Chevy Bells will physically fit Small blocks from 1955 on up, 6 cylinders from 1963 on, and all Big Block engines, W engines, as long as they are Chevrolet engines. GM used engines from other divisions in Chevy cars. But there are major differences to consider such as transmission mounting hole size, clutch fork ball stud locations, z-bar mounting provisions, starter, clutch fork hole location and of course Factory correct application.

168 tooth                               153 tooth

  

Paint:
Most Chevy bellhousings I've come across were panted while attached to the engine and transmission, and have over spray in various places on the inside (starter hole,fork hole) with the outline of trans mounting ears on the front. This isn't heavy just over spray.

Inspection covers:
I've found three different sizes for aluminum bells. 153 tooth,168 tooth and truck. But there are variations in the starter hole.

Date codes:
Most cast iron bells have an alpha numeric code. Aluminum bells? I saw discussion on a forum that the single number over the part # was a date code which I doubt. Manufacturers usually put a number in molds and dies to help with quality control as in (number seven cavity needs maintenance).There are one or two circles divided in half that are Engineering codes and may contain some sort of date code.Some bells have a graph looking thing with dotes also I will try to research these. Date coded parts are cool but not all parts have date codes.

Descriptions of part numbers.