[gtofreek]

With the chamfer against the crank radius, the bearing tangs will be facing in towards the cam. On older rods the oil hole will be on the tang side also. The rods are slightly offset so it does matter how they go in besides just the chamfer and tangs. You cannot turn them around or they will bind. The pistons have 4 valve reliefs so as long as the notch is forward, the piston offset will be correct.

[HWYSTR455]

I thought only some factory, and some 'cheap' replacement pistons had 4 reliefs? My Ross don't have 4, that's for sure. Hm, I haven't used any TRWs lately, can't remember if the 'L's' have 4 or not. If it does have 4, they can be used on either side, and if it's a press pin, it can be offset to either side, right?

i've seen factory rods that have the slight offset you speak of, but it's always been to the correct side regarding the chamfer on the ones that I recall. Aftermarket rods don't have this offset, or at least the Crower Billets and Eagles I've seen don't. Anyway, your saying they would bind against each other if the offsets face together?

[gtofreek]

Originally Posted by HWYSTR455

I thought only some factory, and some 'cheap' replacement pistons had 4 reliefs? My Ross don't have 4, that's for sure. Hm, I haven't used any TRWs lately, can't remember if the 'L's' have 4 or not. If it does have 4, they can be used on either side, and if it's a press pin, it can be offset to either side, right?

i've seen factory rods that have the slight offset you speak of, but it's always been to the correct side regarding the chamfer on the ones that I recall. Aftermarket rods don't have this offset, or at least the Crower Billets and Eagles I've seen don't. Anyway, your saying they would bind against each other if the offsets face together?

OK, let me clarify. The pictures I saw in the presentation were stock Pontiac rods and pistons. Most ALL Pontiacs have 4 valve reliefs[ever taken apart a 301,326,350,389,400,421,428,455? They all have them. The only Pontiac I have personally seen without 4 valve reliefs is the SD-455 which has 1 valve trough. Ross pistons and expensive forged aftermarket pistons have only 2 valve reliefs because they are trying to keep compression up and plus they probably figure since your spending a lot on pistons, they may as well make them better for performance. Yes, the TRW "L"'s have 4 reliefs. Besides how many valve reliefs the piston has is meaningless in this thread as long as they are oriented correctly on the rod. With 4 valve reliefs the manufacturer only needs to make 1 piston for 1 engine. With intake and ex. valve reliefs cut into the piston with a pin offset, the manufacturer needs to make 4 different pistons for 1 engine.

You need to take another look at your aftermarket rods. THEY ARE OFFSET! Almost ALL V-8 rods are OFFSET! They have to be or the small end will be up against one side of the piston[cocking the piston in it's bore in severe cases] and you will have little to no rod side clearence. Inline engine rods are centered. V engine rods are offset. Some may only be offset by .060" or so but they are still offset.

Think about what you said;
"i've seen factory rods that have the slight offset you speak of, but it's always been to the correct side regarding the chamfer on the ones that I recall. Aftermarket rods don't have this offset, or at least the Crower Billets and Eagles I've seen don't."
Now I ask you this; if the factory rods were offset, how in the world would an aftermarket rod work if it were not offset? Answer, IT WON'T!

[PONTIAC DUDE]

Originally Posted by gtofreek

With the chamfer against the crank radius, the bearing tangs will be facing in towards the cam. On older rods the oil hole will be on the tang side also. The rods are slightly offset so it does matter how they go in besides just the chamfer and tangs. You cannot turn them around or they will bind. The pistons have 4 valve reliefs so as long as the notch is forward, the piston offset will be correct.

Ditto.

I have had rods with chamfers pretty radial on both sides of the rods. So the tangs on the same side as race 2 relief is the best way to do it.

As stated above. With 4 reliefs, notch or arrow forward, tangs up.

[HWYSTR455]

Ok, you have a point gtofreek about why wouldn't a aftermarket rod be offset and a factory one is, so I physically looked, and yes, they are offset, just never looked that hard at them or didn't pay attention to it in the past. Not that I doubted it, just never looked since it was the chamfer I was more concerned about.

That brings up another point though, like if the rod's offset, and the chamfer is to the 'long' side, and they only make one rod for both sides, how could one mix them up? I must still be missing something here, or it's just another way of saying the same thing when one mentions the tang orientation? I would think you'd want to look at the chamfer & offset for orientation, and would think who cares about the tang?

On the pistons, that does clarify, thank you. It's been so long since I've even SEEN a factory piston, and have only used one set or TRW/SpeedPros in the last number of years, so I just plain couldn't remember. I'm still confused on the pin offset though. If they have 4 reliefs they only have to make one piston? Then how could the pins be offset? I do remember seeing some with arrows that say 'front' on them, but if you flip that to the other bank, it would be facing the other way, right? The only reason the reliefs were a question were because of the pin offset thing, think that's why it came up. When I used press fit pin pistons, like the TRWs, that had an arrow, I always had the machine shop press them on, and they numbered the rods as well, so, I guess I never paid attention to that stuff during assembly. (Guess I should have). I just looked at the job cards for 3 sets of Ross pistons I have, and none have offset pins. (Or at least it's not mentioned on the job cards). Why then would some be offset and others not? If they are offset, darn, maybe I've just been either lucky over the years or the offset would be something that would particularly make the engine come apart!

I must have taken a lot of the parameters for granted, since these things were generally taken care of by my machinist. Assembly, as from that point on, beyond the rod/piston assembly, were what I felt common sense items, to an extent. Learn something every day!