Installed ARP studs. Should we align bore??

[fishy68]

Ok engine rebuilders and machinists I have a question for you. I'm rebuilding a engine for a buddy. It's not a Mopar but the principal will be the same. It's a 454 Chevy going into a 1 ton 4wd. He installed a set of ARP main studs and the local machine shop says theres no need to align bore it. In the past I've always heard if you install studs you should align bore one. What's everybody's opinion and reasoning on this?

Thanks guys.

 

[dgc333]

You need to at least check the main bores to see if it needs to be line bored or not. Typically with studs and especially with ARP fastners with their moly lube you get a much higher clamping force for a give amount of torque which can cause the bores to distort.

When I built my 360 I used ARP bolts instead of the stock bolts and the machine shop checked the bore after torquing to ARP's specs and there was no distortion and I did not need to line bore.

 

[340mopar]

I align hone, square & make sure the decks' height match (I had a 360 once that had one deck .060 higher than the other) and balance all of my rebuilds, regardless of fasteners used. It adds some cost to the rebuild but when everything is correct and inline it will last much longer and work much better power wise.

But if you are trying to save $ do what dgc333 says.

 

[moper]

Using bolts may not distort at all even when a better brand is used. It should be checked tho. Using studs instead of bolts, you will more than likely have to align hone at least. If you are using a BHJ fixture or similar, you'll have to align hone anyway. It's a standard practice on any engine I do now.

 

[ramcharger]

The stud shafts (Un-threaded part) are thicker and tend to align the cap somewhat differently than bolts do. If you use studs, have it align honed.

 

[dgc333]

I have never seen an engine that the fasteners holding the main caps on are used for alignment, it's just not accurate enough of a way to align the caps.

 

[ramcharger]

I have never seen an engine that the fasteners holding the main caps on are used for alignment, it's just not accurate enough of a way to align the caps.

The machined area on the bottom of the block aligns the caps from left to right, the bolts or studs hold the cap in place fore and aft and help to prevent "cap walk" or the movement of the cap fore and aft as it rocks that can destroy bearings and cranks as well as resist vertical stress. Hence the use of four bolt mains or stronger than stock studs. Personally, if I was a manufacturer, I would use dowels to locate the caps as is used in 14,000-15,000 rpm motorcycle engines producing 170 hp from 1.4 liters of displacement as well as cross bolt the mains through the engine block. I have never seen an engine that aligns a main cap purely by the size of the bolt or stud shank either, but could they have existed in past? Maybe! I was at lunch when I answered the question, so I didn't get into detail.

 

[fishy68]

Thanks for all the replies guys. I looked things over carefully today and found what Ramcharger said is true about the studs being thicker and they seem to want to pull the caps off center as compared to the original bolts. Due to money restrictions the owner decided to go back with the original bolts rather than have it align bored. This isn't a major performance engine anyway so I don't think the studs are really that necessary anyway. This has been a real learning lesson for us so thanks to all who answered.