hey 305 with rod knock suspect rod bearing dont know what piston how do i determine which bearing to replace as i have never heard this motor run ? first time rebuild on 84 t/a 305 quadrajet understand pull the cam shaft and remove pistons and bearings i dropped the pan will there be scarring on the one i need or will it be bent out ?

 

If you get the pan off you will just have to start removing rod caps until you find it. If it's bad enough you can move it back & forth but your still going to have to take them all off anyway. The rod that has the bad bearing will need to be replaced or resized. The crank will either need to be ground under for an under sized bearing or you can buy a crank kit that comes with all the bearings. If you rebuild dont skimp on the oil pump. A new hi-volume pump will make sure the engine gets excellent lubrication.

 

Just a suggestion here but there are many auto dismantlers that carry the L31 vortec motors still at a nice price at that. You would be ahead of the game with the power and less money shelled out.

 

Dont waste the money on a 305. I just rebuilt my L98 that had a rod knock. One spun rod bearing. tore it down, had the spun rod replaced, one was bent and the rest were trued. replaced the crank with a crank kit with matching bearings, entire engine gasket set... once you start spending money, it doesnt seem to end. not worth it for a 305. try to find yourself a complete engine to drop in. you might think you can get away replacing one bearing, but you cant. I couldnt believe all of the other bearings had not spun yet, they were all damaged.

 

If the Harmonic Balancer is rough looking it could be shot. It knocking vibrates the oil
pan and sounds very similar to rod knocking. Be sure to check it before tearing the bottom end down. It’s best to do them all while your into it and have it apart.
Otherwise. A full set of bearings isn’t that much. Especially compared to tearing it back down a year later for another rod beating.

 

Thanks for responding, but I'm sure in the 11 years that have passed, the OP has got it sorted, one way or the other.......