Guys,
I need your help. I am in the process of re-installing my connecting rods in my 1991 3.1L block and I have 2,4 and 6 in. The notch in the top of the piston is toward the front and the bearing tab is away from the camshaft. Problem is when i put in 1,3 and 5 the notch is tward the front, but the bearing tabs are in tward the camshaft. On each of these rods, there is a cast notch above the bottom of the rod and Ive been told those all go tward the rear of the engine. The GM manual doesnt say anything about those, it just says bearing tabs away from camshaft which ill have to swap those 3 rods but that cast notch above the journal will be tward the font. Im confused.. please help i need to get this motor back in the car. pictures attached.

 

What do you mean by "away" and "towards camshaft"?

I'm having a hard time picturing how the bearings are being installed and if there actually is a difference from one side of the engine to the other...

 

in the picture the bearing tabs (some call them bearing locks) on the driver side (cylinder 2,4 and 6) are away from the camshaft (toward the outside of the block). this puts that raised notch (arrow or bump) above the upper half round part of the rod facing the rear of the block. If I put the passenger side pistons (1,3 and 5) in the block with the notch in the top of the piston towards the front, those bearing tabs are facing the camshaft (twards the inside the block but that raised notch is facing the back. hopefully that makes sense.

 

Sounds like someone put some of the pistons backwards on the rods when they mounted them. I've had that happen before. Main thing, if you're not having a bunch of work done, mark everything and put it back in exactly the way they came out from the factory, and you'll be OK. I always marked the rods and caps with a set of stamps so I could always get them back in the same way.

 

thats the problem everything is marked, i want to make sure it is correct the "factory way" when i put it back together... so which way is correct?

 

Sounds like everything is correct to me. The bearings will all have the tang towards the same side of the engine. I'm not sure what you mean by the raised notch.

 

if you look at the picture, at the bottom of the rod, cast into the rod is a raised area (in the picture its on the left side about 1/2 way down. ill attach another picture with circles around the bearing notches and the raised area im speaking about. So if i put the notch in the top of the piston toward the front of the block, that raised area on the rod goes toward the back BUT the bearing notches are facing the camshaft(towards the inside of the block) but im not sure that is correct....

 

As long as all of the bearing tang notches are pointing to the same side of the engine, with the pistons all installed in the correct orientation, it's correct.

I've never paid attention to those bumps that you circled.

 

Not being too familiar with the 60*V6 I did some research on this. As common with many engines the notch in the pistons always goes toward the front of the engine.

As for the rods, the '92 service manual states: "Install with connecting rod tang slots on side opposite camshaft."

I know that older SBC rods have an oil squirt hole to lube the piston skirts. So direction is important. Later a 'shelf' on the cap served this purpose as it tossed lube into the bottom of the cylinder bores.

I'd move the pistons on the rods on the side that the tangs are toward the camshaft.

RBob.