Connecting rod orientation

[MapleDitch]

Hi, I was just about to press my pistons to my rods and noticed the rods are not symmetrical. The piston end of the rod has a square side and a circular side.
Anyone know which side is to face the front of the engine? Or does it even matter so long as all 6 are facing the same way?

258 707 casting rods BTW. Thanks in advance

[SilverXJ]

The oiling hole on the big end of the rod, where the cap meets the rod, points toward the camshaft.

[MapleDitch]

Thank you!

[PolloLoco]

Just for kicks and giggles, how long would the motor last if they were installed backwards? I had the machine shop press on the pistons but I installed them with the arrow on the piston pointing forward. They are KB945 so as long as the machine shop was competent and installed the D-shapped dish properly then should I be okay?

[SilverXJ]

I don't know. I am unsure if the oiling is necessary as Clevite bearings don't even have the provision to let the oil through. King bearings do though. I've heard its to lube the cam and cylinder walls. Not sure about the cylinder walls though.

[amcinstaller]

they teach us in school its to oil the cylinder walls. but with that angle, im not sure either.

[PolloLoco]

I have King main bearings and Clevitte rod bearings. The crankshaft came with King main and rod bearings but, correct me if I'm wrong, the 258 main bearings don't work on the 242 block.

[SilverXJ]

That is correct. The 258 main bearings won't work on the 242 block.

[IH 392]

The main bearings depend on what year the 4.0 block is, '87 -'90 blocks do use the same bearings as the 199, 232 and 258.

[PolloLoco]

So the bottom line is that I need not worry if they rods are oriented properly?

[amcinstaller]

look for the tiny notch in the rod, and point that at the cam. better to be safe than sorry.

[Heck]

The machine shop pressed my pistons (kb 944's) on backwards because the generic instructions that came with the pistons were wrong. I mounted the rods in the correct orientation with the pistons backward. There was barely any difference in the dish shape anyway. No problems after 35,000 miles. More specifically, no cam failure.

[PolloLoco]

I noticed that the shape of the "D" contradicted the direction of the arrow pointing forward. I installed the arrows forward. The dish is shallower than most so I hope that even if they are installed backwards it will still not damage anything. Why is it "D" shaped anyway? How does it improve anything (air/fuel mixing, side forces, combustion efficiency...)?

edit: I should note that I have KB945 pistons.

[amcinstaller]

the D shape should line up roughly with the combustion chamber in the head, and the high part will line up with the flat part of the head. this is so that the mixture is directed at the spark plug. also why hemis have the spark plug in the middle, and no flat spots, just a big soup bowl.

[PolloLoco]

So if I did install the pistons reversed how adverse of an effect will it have on my performance? The dish is quite shallow on the KB 945.