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Cole2534 12-17-2015 08:19 PM

Mild, think about this- your e-bay rod's spot face isn't flat but you don't know that, so you torque it to 100# once. Well guess what now the spot face is flat and normal to the bolt axis, luckily the cap material was India finest bubblegum. But hey! You torqued that SOB!


Did you introduce any preload? Nope. You're hosed and won't know until it's too late.

EDIT- we were typing similar cases at the same time. Torque lies.

Cole2534 12-17-2015 08:25 PM

Think about this. Earlier we got 160,000psi stress in 0.0055". That equates to some torque, say 120 ft/lb. If the spot face deforms .001, and the cap/rod crush a .001 during our 120# torque we've only imparted .0035 elongation - 45% less

But hey! the torque wrench read the same!

Can anyone tell that I like fasteners?

MILD THUNDER 12-17-2015 08:38 PM


Originally Posted by Cole2534 (Post 4386258)
.

Rocker studs are the ones that weird me out, they have no shank length in a highly stressed environment.

Very true. I recently rigged up a dial indicator on a poly lock with hardware in place (rocker, spring, pushrod, etc). Just rolling the engine over by hand, I had about .002 of stud deflection while valve went thru its lift cycle. With just my thumb pushing against the polylock, I was able to get about .004 deflection.

Full Force 12-17-2015 08:53 PM

I think I just pizzed my pants LOLOLOL


Originally Posted by ICDEDPPL (Post 4386211)
I told my wife I was gonna bolt the $hit out of her tonight with my Richard


mike tkach 12-17-2015 09:08 PM

sure glad their is no over thinking going on here,lol.

I'CE 12-17-2015 10:33 PM


Originally Posted by sutphen 30 (Post 4386085)
I guess most of the diy guys are just getting lucky because there sure isn't that much talk about tips failures from bolts.hydrolocking and reversion,yes,but cycling rods bolts.no way
And I've seen and done a ton of Builds that don't do that.everything from cheap stockers,eagle's to Oliver and full out drag race aluminum rods(and these guys go to 9600rpm).
The lube on the threads and back side are more critical as well as stretch if that's the process you are going to use.

u sure

MILD THUNDER 12-17-2015 10:48 PM


Originally Posted by I'CE (Post 4386301)
u sure

You saying the bolt cycling is necessary, or that theirs been failures ?

horsepower1 12-18-2015 07:15 AM


Originally Posted by Interceptor (Post 4386177)
I know I'm being a dick but.....................Just to be a technically correct those fastners you're all talking about are called screws not bolts. A screw goes into a threaded hole in the mating part, a bolt is secured with a nut.
and
I'd still be equally concerned with bad threads in the rod causing a issue vs the screw.

You're absolutely right and to be even more accurate, they're called cap screws, not just screws.

horsepower1 12-18-2015 07:28 AM

If any of you are really interested in learning about fasteners, there is a book that is my Bible on this stuff and it's written by a guy named Carroll Smith, called Nuts, Bolts, Fasteners and Plumbing. If any of you have an ARP catalog, you'll see a tribute to John Carroll Smith somewhere in the beginning. He was one of the early contributing engineers at ARP and worked throughout the racing industry. This book is a great read for anyone interested in this sort of thing. It's out of publication but I'm sure you can find copies on EBay and such.

F-2 Speedy 12-18-2015 07:32 AM


Originally Posted by MILD THUNDER (Post 4386264)
Very true. I recently rigged up a dial indicator on a poly lock with hardware in place (rocker, spring, pushrod, etc). Just rolling the engine over by hand, I had about .002 of stud deflection while valve went thru its lift cycle. With just my thumb pushing against the polylock, I was able to get about .004 deflection.

This is the reason for stud girdles, to minimize the deflection and help stabilize the valve train, I'll tell a little story that BS told me and if it wouldn't have came from his mouth in person I doubt I would of believed it. So he's building a pretty healthy small block for one of his customers, made a couple pulls and it made good power, then the guy shows up with some girdles and they get bolted on, another dyno pull and gained 15-20hp, he didn't believe the numbers so he pulled them back off and the HP gain was gone, True story from the man himself with his father Bob as a witness.


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