Resizing stock rods for ARP's

[rr06rs]

Is it truely necessary to resize the rods when using ARP's? I know the added torque put to the ARP's will cause the rod bore to SLIGHTLY change shape over the stock bolts and tq specs but I really can't see it distorting to a "football shape" as some have said. Also, has anyone installed ARP's w/o replacing the bearings. Basically, just a "drop in" procedure?

 

[dented_coffee]

Have them align honed and never re-use old bearings. You will run into bigger more expensive problems down the road from skimping on a crucial part like this. I have seen spun bearings and destroyed cranks from not having the rods worked after ARP's were installed.

Do it right the first with the correct parts.

 

[turbo23]

Yes, you have to have them remachined. Its not just the added strength of the bolt, its the removing and installing of the bolts that also distorts them. Spec is really tight, so it doesnt take much to move them out of spec. Typically when i get a set of rods, There out of spec before i change the bolts. i dont let them go untill there within 2 tenths.

 

[kthackst]

The ARPs have a slightly bigger diameter than the stock rods. It looks like it will fit but they dont. The ARP will stop about with about a 1/4" of the way left to go. And I used a press to install them. I found out the hard way... Get them align honed.

So yes i tried and failed.

 

[dented_coffee]

The sleeved bearings in our engines are a crush type. They crush just a very little bit to my understanding. If the rod's cap is off by the slightest it will push on the bearing in that area causing heat. By that heat beeing caused your chances of spinning a bearing are very high.

When you put the caps back on the rods for re-install make sure that its tang to tang (the little dip that holds the bearing from sliding sideways). I have seen some people put them in backwerds with a tang on each side and it threw the bore of the crank end of the rod out of spec and spun a bearing because of it pintching the bearing to tight.