Mealticket

I know the fuel injection wiring harness anchors to a couple of the studs but that can't be why they're there. I wonder if the factory used them to install the engine? The reason I ask is that I'm going to fab up a lifting plate.

djb383

Studs offer superior clamping force/torque readings compared to bolts.

87Warrior

They make pulling and installing the motor a piece of cake!

CCKen

Guess the head bolts under the valve cover don't need superior clamping force.

DFlintstone

Something needs to hold the harness. That's a pretty simple solution compared to any alternative I can think of right off hand. Oh! Probably made $ for Jeep as well, selling them.

djb383

Studs are superior......however, cheap bean counters prefer bolts.

Mealticket

Guess I'm not grasping something; if the bolt head is integral with the bolt that screws in to the block, then how is that different from a standard head bolt? The 'stud' is on top here...


Mealness

skife

it's not, most people here just don't take the time to read what people have typed.

MonacaYankee

Don't bother with a lifting plate. Use chain with a spacer then a nut on top. Put some rags between the valve cover and the chain on both sides...how I did it anyway.

It was probably cheaper and easier for the factory to use the head bolts like they are instead of making two different kinds, one to hold the electronic rail for the injectors . Probably install and engine building reasons to.

djb383

Google stud vs bolt.

JeepingDan

Ya really plan on yanking the engine out that much? Lol
I usually just find a couple bolts that will screw into both ends of the head and pump it out!

5-90

If they're proper studs, installed properly, yes.

These aren't proper studs with separate nuts. These are simply screws that have a stud top.

You've noted that two of the studs are used to hold standoffs for the fuel injection subharness - not strictly necessary. The rearmost stud is used to attach the engine-to-chassis ground and retain the clip to keep the CKP wiring off of the #6 primary tube. However, the ground strap may be relocated to the rearmost fuel rail screw without incident; and if you're pulling the head, you can fabricate a small retainer clip to duplicate the OEM function (it's been a while since I've seen one, so I don't know if it can be drilled out. The cylinder head side of that screw is threaded 1/2"-13UNC, the top side is 7/16"-14UNC.)

DFlintstone

His translator is on lunch break. I think that translates to, "CPS wires off the exhaust manifold"

And thanks for the clarification. I couldn't imagine how that little threaded "hat" on that bolt could make it any stronger. (OK. "screw....

ajk0204

I believe with studs you can go to higher torque values than with bolts because as you tighten the nut it does not transfer as much torque/shear stress to the stud you do with a bolt.

Mealticket

Thanks for all of the responses. For my purposes I like 87Warriors' note. Following up on the torque thing for bolts/studs, I did Google it. Here is the money shot, validating ajk204s' comment:


'By contrast, a head stud can be tightened into place without any direct clamping force applied through the tightening. A stud can be threaded into a slot up to “finger tightness,” or the degree to which it would be tightened by hand. Afterward, the cylinder head is installed and a nut is torqued into place against the stud. The nut torque provides the clamping force, rather than the torque of the fastener itself, and the rotational force is avoided entirely. Because the stud is torqued from a relaxed state, the pressure from the nut will make it stretch only along the vertical axis without a concurrent twisting load. The result is a more evenly distributed and accurate torque load compared to that of the head bolt. This ultimately translates into higher reliability and a lower chance of head gasket failure.'


As some have noted, that's not the case on the 4.0. The hex bolt head is integral with the bolt section. The 7/16 'stud' section above is there for another reason. I bet the factory used them for install,

Mealness