ARP main stud installation question 440

[440Dakota]

I've read different posts and watched videos with varying answers on whether the studs can simply be screwed into the block or if the Block has to be line bored? I have the mains set and torqued with factory bolts... If I was to loosen all the bolts with just a slight pressure on each cap then working center out take one bolt out, screw in a stud and nut snug, then the other side doing this cap to cap followed by the correct torque sequence would I be ok? Since the caps are set in place I wouldn't b think they would move unless the studs are larger diameter with a tight fit in the caps.

 

[diesel_lv]

If you are changing from bolts to studs, the block must be line honed w the main caps torqued using the studs. The clamping forces are different.

 

[steve340]

Plastigauge the bearings with the old fasteners and then the new ones. Done properly this will tell you for sure.
This will involve removing all oil from both halves of the bearings to be accurate. To be done absolutely right you would need to remove the crankshaft and wipe clean the crankshaft and bearing shells.
I know the clearance will not change much but it will close a little - yes I have done it. The studs will clamp more but only torque to the factory spec.
An ARP stud with their lube on it will be much tighter than the factory dry or lightly oiled fastener.
The engine I did this on was completely down and I could check it was rotating correctly.
Proceed carefully if the motor is fully assembled.
If the bearing clearance is on the tight side with the factory fasteners I would say don't do it.

 

[Nate S]

I’m a mechanical engineer and have worked with many fastening systems over the years, being responsible for creation of large machinery for 25 years. Your plan is absolutely fine on the surface. The final system and its stresses will be nearly identical to the system as it is today if you torque to factory spec and the studs have the same thread pitch as the bolts (on top).

That said I went and looked at the ARP page and the instructions. They have fine thread and a recommended torque of 110 ft-lb rather than the factory 85. This is not the same. You’d probably get away with it ok but what for? Is there some particular thing you want to achieve by making this change?

 

[yella71]

Right well here's another varying reply....First off what makes you think you need main studs? second dont bother dickin around changing from bolts to studs one at a time. Remove all the main bolts and caps put the studs into the block and put it back together. As long as the caps don't bind on the studs torque everything down as you normally would. Ok Next...

 

[440Dakota]

Thanks gentlemen for the replies.. one reason to change to studs is that these factory bolts have been torqued a few times and another is to run a main girdle on this engine.. I've never had an issue with any other engine running factory hardware but this engine is a little more built than they were..

 

[diesel_lv]

Thanks gentlemen for the replies.. one reason to change to studs is that these factory bolts have been torqued a few times and another is to run a main girdle on this engine.. I've never had an issue with any other engine running factory hardware but this engine is a little more built than they were..

My 383 is stroked to 496, I've got 610hp/670tq at the crank, bolts are just fine. No girdle needed.

 

[padam]

I would not install studs if you're not going to torque to the stud spec.
You need the proper tension on the fastener, and at a lower torque, you won't have it.

 

[fbs63]

One thing people don't think about with studs. They are 1/2" constant diameter the whole length. Stock bolts are necked down between the under-head pilot and the thread diameter. This is so they flex a little when the cap is torqued down in case the bolt hole in the cap is a little off square. Sometimes the cap holes need to be reamed or drilled larger so the cap seats properly. If you ever had a crank not have end play or not turn after the caps are torqued this is usually the issue. Also the extra clamping force of the studs at 110 lbs vs bolts at 85 lbs distorts the main bore.

 

[pnora]

I doubt you will have problems switching to studs. Those caps wedge so tight within the block that there is no place for them to go. Thousand of engines have been swapped to studs and not line bored. If its a fresh build and you want it line bored now is the time to do it. Any time you get a used core for a build it should be lined bored to be sure as you have no idea what is there.

 

[zyzzyx]

I agree with Steve340. If the main bores are at the top size limit, you won't have a problem.
I had my engine down all the way and installed the bearings and crank. I then put in the ARP
studs and torqued them to 100LB/FT. Turned the crank easily. The difference between 85 and
100Lb/Ft are tenths of a thousandth of an inch. If the bores are tight, you'll bind. Caps are made
of cast iron and they don't compress, but more torque will make them seat "Tighter". The main
reason that you use studs or better rod bolts is the caps have more hold-down power and they
can't lift during high RPM.

 

[Charged440]

When I get a hundred different answers I usually go with what the manufacturers instructions say.

 

[pnora]

When I get a hundred different answers I usually go with what the manufacturers instructions say.

When you do not know anything that is not a bad idea. They instruct in such away that no liabilities can applied to them. They also can make you dig deeper in your own pockets.