bence13_33

I am currently starting to assemble my engine tonight. I am installing my ARP main studs. In the directions it says that the studs should only be installed hand tight :confused:. Does this mean screwing it in with my fingers until it is tight, or putting an allen wrench on the end and cranking it down until it is tight?

Why only hand tight? Wouldn't the studs be more stable if they were really torqued in, or do they torque themselves in whenever the main caps are torqued on? I won't be using loctite either.

Pete79L82

Bence;
When you put main studs into the block you only install than hand tight. Then after you install the caps you torque down the nuts. If you try to tighten them more than hand tight there is the possibility of cocking them. Then when you torque down the main caps it may not apply the torque evenly. Just be sure you run a thread chaser through the holes first so you are sure the studs are going in all the way to the bottom.

bence13_33

Pete:
Thanks for the info! I'm just worried about them coming loose during operation if they are only hand tight. Do I need to worry about that or will they stay put?

gkull

Okay I got out my last ARP main stud directions. "Hand tight only!" Did you also follow directions about thread chasing? The reason is - By preload torquing them down you would really be torqing the threads when you add an additional70 or 85 ft lbs on the nuts.

The only thing I was ever taught about assembling a studded motor is I set all the like studs to the exact same height. Hand tight can't do that. So I put on twin nuts to sink the taller one down past where they have to be and then back them off to the correct height so you dont have any preload. I used 30 WT oil because I preferr the 85 ft pounds of final tq.

Any other questions?

RatRacer

They will stay put once you torque down the nuts.

Pete79L82

When you torque the nuts down it will apply pressure to both sets of threads (block end and nut end) so they will not come out. I can not overstess the importance of being sure the thread are good and clean in the block and that the stud will easily thead all the way to the bottom of the thread hole. If there is any rust or debree or a rough thread you will not get a good torque seating on the stud.

norvalwilhelm

Like George I use 2 nuts on the stud and after chasing the threads with a tap run the stud down and makes sure it goes to the bottom. I also check that they are installed at the same height. If you only used your hand what if one of the studs was a little sticky and didn't really go all the way to the bottom. Use 2 nuts , run them all the way to the bottom but do not snug them up.
I was under the impression when you used a bolt only the top 3 or 4 threads really held any load and the rest took very little. With the studs screwed lightly into the block all of the studs takes the load, all threads deform equally to spread the load out. Torquing the stud would end up like a nut with only a few threads taking all the load.
Studs are a pain. I use them but don't like working with them. Check all clearances with the old bolts and save the studs for the final installation. Try removing a tight main cap to check clearances with studs and it is alot harder then doing it with bolts. Same with the heads . Install a head with bolts to check piston to valve clearance and save the studs till the very end. Even the head is difficult to remove with all the studs sticking up.
Good luck Bence

gkull

In responce to Norval: He's right about doing everything with your old bolts first.

The very first head studded motor I ever built I had a heck of time getting the head gasket on. So I took the block back down to the machine shop for blue printing. Because old blocks have warped and distorted or maybe not even done right from day one. So the studs are sticking up at all different angles.

After that experience I ALWAYS paid to have the block blue printed. They retap all the holes in correct alignment.

fauxrs

Make sure if you are chasing the threads use a chasing tool as opposed to a regular cutting tool - you do not want to recut the threads. Also once the studs are in - install the crank and torque the caps on to their proper rating, this will help ensure the studs take their proper alignment. Remove the crank and then have the main Align honed, with the caps on and fully torqued.