- Jan 2, 2010
- 69
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I'm rebuilding my 302 and I'm having some issues here. I bought new pistons and pressed them on the rods and now that I'm putting the motor back together I can't get 2 rods to fit on one journal.
IF YOU MIX THE RODS UP FROM THE ORIGINAL HOLES IT WILL THROW THE BALANCE OFF AND THE MOTOR WILL SHAKE AT IDLE. YOU SHOULD NOT HAVE TO REBALANCE THE ENTIRE SET UP FROM JUST SWAPPING PISTONS, REPLACING RODS WITHOUT THE CORRECT WEIGHT OR REPLACING THE CRANK AND YOU WILL NEED A BALANCE.
There are two different syles of rod bearings... ones that that are designed for a chamfered crank journal and ones for non chamfered crank journals. If you have a stock crank, you need the chamfered ones. If you look at the crank journal, the area where the shiny finished round journal meets the unfinished vertical part of the crank, it's not a sharp inside corner... it is rounded off. ( see pic below/red arrow)This mandates use of bearings that have a bevel on one side of the bearing... this side must face the rounded inside corner... so when both rod bearings are installed, the bevels on each must face away from each other. You may just have the wrong bearings or you have the right ones and they aren't oriented correctly. Many a new engine builder has not taken this into account and suffers the consequences... don't be that guy.