FJ24 Connecting Rods
As the engineers developed the FJ24 from the FJ20 a particular concern was the integrity of the connecting rods. Not that the connecting rods on the FJ20 were a weak point but as the engine would be used purely for competition it had to be reliable. Therefore, the decision was made to make a very heavy and very robust rod from CM40 steel. The journals were 53mm which was a size shared with the FJ20 rods, the length was 140mm again similar to the FJ20 but the small end was reinforced and the rod much thicker in width than the FJ20 item. Another very important feature of the rod was a chamfer around the journal. This coincided with webs on the crankshaft. The angle and size of these webs are unique so only FJ24 rods will fit an FJ24 crankshaft. The engine could rev safely upto 7500RPM in standard trim. This could be pushed out to 8000RPM if the rods were given a mirror finish. This was popular and all factory engine had polished rods. Bill Blydenstein also advised polishing of the rods. Over the years I have seen variations on the amount of polishing done to a rod. I have seen complete rods top to bottom polished and others with just the flats on the stem. The inherent strength of the I beam design is well known and the FJ24 rod is no exception. It is common for the small end and big end journals to stretch and malform rather than fail. An excellent if slightly over engineered and heavy rod that's well equipped for the job. The pictures below are some rods I am preparing for an engine. One rod was very highly polished to begin with. The others weren't for whatever reason. There is some evidence of use but the journals are round as are the small ends so my guess is these were pulled from an engine but never refitted.