Arp main studs.

I'm in the process of getting everything lined up to build my engine. It's getting bored .020. I was sent arp main studs, and they recommened torqueing the studs, then checking the line bore to make sure everything is still within spec. The machine shop that will be doing all of this advised against it. Saying the backlash between the crank and cam may not be right after. May eat up the gears.

Listed here in the footnotes.
http://arpinstructions.com/instructions/150-5802.pdf

So should I use the factory bolts? Studs neccessary? My build consists of dual fuel, 60%, jr high powers, Carrillo rods, Pistons, stage 2 cam etc

I 've had two big block Ford's with girdled bottom ends, and each one was line bored. Granted they are not gear to gear for cam drive but the machining required is the same. The reason ARP wants it checked, is to be sure the main bearing surfaces in the bed plate and engine block do not distort or "egg-shape" when torqued spec. They shouldn't be condemning the studs to automatically causing gear failure. Although it is something that would definitely need checked and watched.

Doesn't hurt anything to pop them in and see what it looks like. I'm sure if you dig hard enough you can find a Ford/International spec on line boring, if you would need to go that route. There has to be some allowance in the location of the crank and cam, not all of these blocks are going to have them located in exactly the same spots.

So is the juice worth the squeeze? I've never heard of an issue on a 6.4 that had to do with the main bolts failing?

i would skip it unless you are planning to make well over 1k hp