it's something that's overlooked and not fully understood, the hows and whys of using stud fasteners..

-supposedly studs have more holding force than bolts, and combined with fine threads and proper lube, torque....voila..!!
-in automotive apps, it's usually the mains for the crankshaft...then the heads to the block for higher performance jobs etc..

-threads consumed...good one Neil....other option would be stud bottoming out...not good

I would venture a guess and I will let you know tommorow got my torque wrench 100-600 ft lbs and it is a beast.. My prediction is that the idiot didnt and I mean not me prior hack job never torqued down properly.... I know that needs to be torqued and I have all the sequence ect.... What a PIA.....

Hi Team,
scan below shows the special Torque for Caterpillar Taper Lock Studs.
These studs do not bottom on the shoulder of the stud thread or the deck surface--they have a taper ground onto the entry end of the stud to match a taper cut by the threading tap down at the bottom of the block's threaded hole.
Thus the surface of the block deck is not distorted by the bottoming of a stud thread shoulder that can lead to cracked corners of castings.
Needless to say the threaded hole needs to be fully cleaned of any dirt, oil water, etc. to save hydraulic pressure build up from cracking castings when screwing in the stud--seen it done--not a cheap fix to repair.

I have also seen threaded holes ruined by the unknowing taping out the threaded hole with a plug thread tap and so leave no taper for the Taper Lock Stud to bottom and lock onto and so the stud bottomed on the shoulder and cracked a casting.

Be careful out there as Cat use some refined methods of retention that are not industry standard.
Note also the reduced Torque for Hydraulic Valve bodies and the like

Cheers,
Eddie B.

exactly Mr Ed...be extra careful on assembly...super clean...esp threads etc....if you have compressed air blow everything clean and dry...all holes and blind holes etc....

-if things aren't going together well and smoothly...slow down and ask questions...esp from experienced cowboys (not their first rodeo guys)

Clearly, the taperbolts need to be torqued down first but I would venture a guess that when the majority remove head they assume the taperbolts have not moved and thus dont touch them.  In addition I would venture a guess that when the head is removed you double nut them to remove them and of course retorque based on lenth according to chart giving you value of torque? The only problem is I need to remove the eye hook double nut it and do not have an idea without removing completely the taperbolt.  Does anyone out there know the size of the  taperbolt on the head of a d353 engine?  Much appreciated... I will be doing it today... Mahalo George 

A lot of bogus advice for this application. Those are not taper lock studs. Listed as 3/4" nominal "Plain Studs"

well that's not all bad news...."nominal Plain Studs".....would that be "grade 8"?

-don't stop now O M....how would you proceed?

-nobody has said what the "nominal Plain Studs" are supposed to be torqued to in ft/lbs...whether the threads are consumed or not if the stud bottoms in the hole(block in this case)
-this is a good thread(sorry)

Thanks OM as always.... I appreciate everyones input and either way it will be sorted out.