rodent

iTrader: (1)

I recently got my forged 6.0 shortblock finished but the shop didn't use ARP main studs. Is it possible to install the ARP main studs or will that cause problems with the main bearings.

The engine will eventually be FI but maybe nitrous for now.

I just don't want this to fail under high hp conditions. Everthing else has ARP/H11 bolts/studs.

Has anyone here had a failure from the stock main bolts/studs?

CHRISPY

You can run stock size Mainstuds (which should be plenty)

BTL FED

iTrader: (9)

The block should really be line honed if you are going to install main studs, because the studs put there clamping force in a different location that bolts will. It may be fine, or it may eat the bearings up in 100 miles

CHRISPY

thats true! For some reason I thought it wasn't together yet

parsonsj

First I've heard of that and I'm a bit skeptical. Exactly how does the stud clamp differently?

John Parsons

rodent

iTrader: (1)

Thanks for all the replies. I guess I'll just stay with the stock main bolts.

BTL FED

iTrader: (9)

Sorry took me a while to see that someone had a questions on what I posted:

When using a bolt on the mains the threads in the block are used to apply all the clamping force, when using studs the nut on the top of the stud is applying the clamping force:

Here is an example:
A buddy of mine had a engine line honed with stock bolts, the machine shop said the clearance would be .0023, once he got the block back he decided to put studs in the block, it opened up the main clearance to .0043, I told him to put the stock bolts in again and check to make sure the machinest was correct, sure enough with the stock bolts it was .0023

Hope this helps
Kyle

parsonsj

Kyle,

I'm still skeptical. The clamping force (whether bolt or nut) is a linear force in the direction of the stud or bolt. The thread location makes no difference in clamping force. Studs are ordinarily thought to be "better" because they exert a more linear clamping force during the tightening sequence because the bolt isn't being twisted as it is torqued. The feedback to the torque wrench is direct on a stud arrangement, while with a bolt the length of the bolt has to be factored in. That's why torque ratings depend on the length of the bolt as well as its diameter.

My guess about the .0023 vs .0043 case you mention is that your buddy may have had a bent bolt. Or it's possible that using the same torque reading on a bolt vs a stud generated more linear clamping force and changed the clearance. In general, the stud torque reading is probably more trustworthy. I'd think the "real" clearance is probably more likely .0043.

Or am I all wet? Does everybody else line hone when swapping to main studs?

jp

BTL FED

iTrader: (9)

Here is a little info on the clamping force difference from the arp website:

MAIN STUDS vs. BOLTS

ARP® recommends the use of main studs over bolts whenever possible for several key reasons. First is the ability to obtain more accurate torque readings because studs don’t “twist” into the block. All clamping forces are on one axis. By the same token, there is less force exerted on the block threads, which contributes to improved block life (very critical on aluminum blocks). Finally, there are factors of easier engine assembly and proper alignment of caps every time.

Here are some of ARP's instructions on Main Studs, if you look at step 5 it advises to have the block line honed

http://www.arp-bolts.com/pages/produ...ks/how_to.html

parsonsj

Kyle,
Good info from ARP. I see where they recommend align-honing. It is kind of odd how they do it though: last and in a picture caption, after things such as install main caps; check for binding and misalignment, lubricate threads, nuts, and washers. Use moly lube.

You'd think they would say it first and in the introductory paragraph: "The use of ARP's main studs require the block to align honed." Then go into proper assembly techniques. The way they did it seems like an afterthought.

But good info anyway.

thanks,
jp