Engine Builders: In an effort to clarify the confusion about connecting rod bolt torque specifications used in various Allis Chalmers agricultural or industrial engines, the AERA Technical Committee offers the following information. This information applies to both early and late style engines, as several different hardware combinations have been used in the 201, 301 and 426 c.i.d. engines.
Two different connecting rod and cap mating surface finishes were used and identification can be made by visual inspection. Early style connecting rods have a serrated mating surface between the cap and the rod. Middle and late style connecting rods can be identified by a flat parting line between the cap and the rod.
To assemble, use a light amount of engine oil on capscrew threads and on the underside of the capscrew head. Tighten cap screw using a minimum of two incremental torque steps or three steps on higher torque hardware (7.0L). Non-serrated connecting rod caps MUST be aligned with the rod during installation. To do so, install hardware finger tight, use two feeler gauges between the rod/cap assembly and the side of journal to hold assembly snug to one side of journal. Tighten hardware in multiple steps and then remove feeler gauges.
2000 series, 3.3L and 4.9L series engines
(2200, 2800, 2900, 433 & 649 types, etc.)
Early-style rods use hex-head capscrews with washers and the rod cap bolt holes have a 30