Rod Bolt Stretch

[jimm II]

Was assembling my rods on to the crank;when #6 rod bolt grew.
The recommended stretch is .006" to .0067" at 50 ft/lbs torgue.
The bolts are ARP wave lock. The bolts were coated with the ARP lube as instructed; and torqued in 5lb incriments, from 10 ft/lbs to 50 ft/lbs.(I have a Rod bolt stretch gauge that I was using at the time ).
To the point the pistons that I have already installed have come up Fine,but on #6 inner rod bolt @ 45 ft/lbs started to grow with the stretch gauge on it ...to .0105"... The question is IS THIS rod bolt History??????

[6 packin]

How much did the others stretch? If not much I would say yes. That sucks man, there the best rod bolts out there too. I would call there tech line, see what they say.

[jimm II]

In regards to the other bolts stretch.Pistons #1,2,3,&4 came up to .006" to.0065" all good at 50 ft/lbs torque.
Since posting the first time I installed two more pistons the same way as the others.One bolt on #5 over stretched at 35 ft/lbs and #7 rods came up to .006" & .0063".
#8 bolts started to come up to torque then the outside bolt @ 40 ft/lbs went away....while the stretch guage was on it . It climbed to .0105 then leveled off...
Loss three bolts total:... guess it could have been worse,could have not checked them. Now I'm in search of wave lock rod bolts... Thanks for the replies guys..

[biggerhammer]

that is why I never use ARP, always happens, even following their directions and using a stretch gauge, I use Pioneer performance rod bolts, have yet to have a failure due to the rod bolts, lost count of how many dirt track engines I put them in.

[jimm II]

Not so sure that I can blame ARP just as yet;the rods are Eagle I beam. When I had to undo the cap nuts this morning,they were VERY tight .Had to place them in soft faced Vise and use the long torgue wrench just to loosen them.
One more Question guys: On the shelf I have a complete set of mopar performance rod bolts #P4120097 for small blocks...they are stamped with ARP on nuts and head of rod bolts. They are Not the serated type but are smooth.I know they are not the wave type but would they be an Equal substiute....????

Thanks guys

[dewme5]

isn't rod stretch the correct way, and ft.lbs. more of a good guideline to get there? .006 is .006 no matter how much or how little you have to turn it.

[MitchB]

Those bolts with excessive stretch are now in partial failure. They are not to be used. Good thing you measured stretch or you would have found out the hard way.

Mitch

[jimm II]

Thanks for the replies; I will be changing them out right

[dirty dan]

Originally posted by jimm II
Thanks for the replies; I will be changing them out right

Hey jimmII
Jusy a thought.
Have you had your tourqe wrench calibrated Lately.
It doesn`t take much nock them out of spec.

[jimm II]

On the torque wrench had it calibrated back about October of last year, by Snap on dealer .Also had a back up torque wrench just in case . But I was relying on the Childs & Albert stretch guage as the final torque...good thought though.

[don340-4]

jimmII, I,m also installing Eagle rods w/ ARP bolts in my 340, like you I found the new out of the box rod bolts extremely tight had to put them in a soft jaw vise w/ a long breaker bar to get them loose, i don,t have access to a stretch gauge was just going to torque to 50# per the spec sheet, should i be concerned about these bolts failing?

[pishta]

Those bolts are designed to stretch a certain amount and contract. That way they keep the rod on the crank at load. If you stretched one out, you have exceeded its preload and it is junk, like a spring in a ball point pen. You pull it a little and it will contract back to its original form. You pull it farther and it will never go back to its original form. As for the bolts stretching at different torques, I would return the culprits and demand replacements. I would still use the stretch guage for the final say so, but having a torque wrench to measure when the stretch starts to come on is the safe way. That is a bummer. I thought ARP was on top, I used Pioneer myself, but lost a rod anyway due to unknown circumstances..

[jimm II]

Find,beg or borrow a stretch gauge.
What I found out about the bolts from ARP (I phoned them); is that they manufacture the rod bolts, for Eagle and the rod bolts are manufactured to the SPECS for Eagle presented to them by Eagle......
Regular mopar bolt length from bottom of head to end is 2.046"
The bolt out of the Eagle I beam rod is 1.926"long (special)shorter.
I've just found Eagle's phone number and will contact them this evening.....keeping my fingers crossed.

[don340-4]

jimmII, let me know what you find out from Eagle (part # for the bolts they use) i already had everything balanced so i need to stay with the same bolts.

[jimm II]

I contacted Eagle Specialty Products about my rods I explained what happened on the three rods.
They needed to know the large end weight (418 grams) and the small end weight (200 grams). They said they would try to match them up and send three replacements. But if they could not match them up they would send a complete set.
Just sending rod bolts, would cause the rods to have to be resized, an additional cost. It would probably be more cost effective to replace the rods.
Anyone got an EASY way to undo spiral locks.Double locks on each end.(Ross pistons) Just have to wait now for Eagle Rep to get back to me.

[jimm II]

Eagle Specialties got back to me ; they were unable to match up the weights so they asked that I send all (8) back. and they would replace them it may take a week or two they said..
just an update.