98.5POS

Thanks for all the posts and advice - I broke down today and bought a new truck. I haven't decided the fate of my trusty 98.5 yet.


I'll bet you're wondering what I bought? Well, after spending about 3 hours with a salesman from a local dealership I decided to check out a different brand of truck. Low and behold they had exactly what I wanted! A 1 ton, 6spd manual, 4x4, cab chassis! I drove it home tonight and fell in love. Are you still wondering if it's a 6.6 or 6.7? Well...............

dieselfan

i hope its a 6.7 or 5.9! what is it?

dieselfan

yea but why the 98ftlbs on the 3rd retorque and 120 for all the others?

98.5POS

6.7!!

DH

dieselfan

I knew you would make the right choice. good luck with it and by the way keep the 98, everyone needs 2 trucks.

Forrest Nearing

was scared of overstretching the studs... wanted to make sure that the o-ring was good and dug into the gasket. the first two were because I didn't have moly... the next was shortly after to make sure I had a good even clamping load. then a month later I installed the hot injectors and bumped it up to 120.

I'll probably do another here before too long

Cummins Freak

yeah i'm also with big blue if it can't be fixed with 12mm studs just tap it out to 14mm studs. Also to bad about your luck

boostjunkie1

------ He didnt have any problems with the Head Studs !!!!! He just needed a good enough reason to go out and buy a Cab and Chassie!!! Keep the old Truck and finish your project!

Forrest Nearing

I'd heli-coil it... only real way to go to 14mm studs is to pull the block

xtoyz17

As Forrest said, hand tight for the studs. Anything more than that will put a small amount of stress on the studs, which might not even be measurable in the real world. Does anyone know what the studs are made out of? It would be easy enough to do a little bit of math to find out where the studs "should" start to stretch (what torque the studs would exceed their yield strength).

Forrest Nearing

ARP says 96ftlbs w/ moly = 75%

I think 125 w/ moly is right there on the edge of elastic

Timmay2

I dont know whether to say welcome to head studs or welcome to ARP?

<= With bigblue on tapping it for the next size up.

dieselfan

yea but why wouldnt the 120ftlbs w/ 30wt stretch them, but the 98ftlbs w/moly would, does it pentetate more or something?

thanks, brian

getblown5.9

moly has a better co-efficient of friction...when you hit 96lbs with the moly its pretty much applying the same DOWN force on the head as it would with 120 and 30wt. the extra tq on the nut is being applied by the friction required to turn the nut. its still giving the same clamping force...it just takes more force to turn the nut when 30wt is used.

i know this isn't the best scientific explanation but i hope you understand what im saying.

xtoyz17

But it's dead on. The force of friction from poor lubrication is creating torque numbers from the wrench that are higher than you would see from moly lube if they were both placing the same amount of axial force (force parallel to the stud itself).