I just finished putting all the pistons back in the 454 and I get to the torqe spec for the rod bolts. ARP literature with the bolts say to use a stretch gauge, which I have, and stretch the bolts .006 to .0067.
If you don't have a gauge, it says to put them to 50 lb ft three times and let it go.
I tried to stretch these to .006, and it took 75 lb ft to get them stretched .005.
I got real nervous and did the 50 lb ft method three times with the moly lube.
This only produces .0025 of stretch.
I called ARP and asked why the big discrepancy. They said to cycle the things 5 times at 50 lbft and I would get .006 stretch. It ain't so. Cycling 5 times gets me .0025 every time.
I am looking for advice here on which to go with. Right now, I am on 55 lb ft @ .003 stretch. Any serious advice is welcome. I still have the pan off.

Dave

Dave,

I tested the bolt stretch on a set of stock SBC rods a few years ago. With 50w oil on the threads and flange of the nut, it took 75 ft-lbs. to get the proper .006. With the ARP lube on the thread and flange it pulled right up to .0063"-.0065" on the first torque of the bolts.

The only suggestions I have is that could the rod have a crooked face that the nut is touching? It seems like there is extra drag on the nut. I would just check the face of the rod cap to see if there are any high or shinny spots that look uneven. I kinda doubt that you will find anything, but you never know.

The only other ? would be is you rod bolt stretch gauge flexing? Can you repeat the measurements on the same bolt several times?

Good luck and let us know what you find out.

------------------
R.J.
1972 Chevelle
TC Member #1525
RJ's website updated 12-1 (http://www.buffnet.net/~airrj/)
2003 Northern Chevelle Gathering (http://www.angelfire.com/folk/canam/page35.html)

Are you using ARP lube or oil? It makes a difference.

------------------
Pat Kelley
66 El Camino, daily driver
67 El Camino, STRIP/street (7.392, 92.70, 1.63 60', 1/8 mile) 355 powered
Pat's Page (Dynamic Compression Ratio Calculator, car specs, Spark plug reading info) (http://cochise.uia.net/pkelley2/)

Pat... I am using the Moly Lube ARP recomends.

RJ... I did notice some shiny spots on the nuts, but is it pretty concentric or even aroung the nut. Plus, the results I am getting are identical for all the bolts.

You mention that you went to 75 ft lbs.
Did you leave them at that?
Is the engine running?
What diameter bolt is used in a 350?

Dave,

I did the test in a rod vise. No I didn't run the motor with the oil and 75 ft/lbs. Since then I always use the ARP lube and 50 ft/lbs. I don't have my own stretch gauge and so that was a one time test for my own knowledge. And the SBC bolts are 3/8".

Sorry I can't help you more.

------------------
R.J.
1972 Chevelle
TC Member #1525
RJ's website updated 12-1 (http://www.buffnet.net/~airrj/)
2003 Northern Chevelle Gathering (http://www.angelfire.com/folk/canam/page35.html)

Dave,
Are these 3/8 or 7/16 bolts ?? The 7/16" bolts are torqued to 75 or .008 stretch. I have never had a problem just using the ARP lube and torqueing them to 50 on the 3/8 bolts. Make sure to use plenty of the lube, and make sure you have it on the face of the nut where it hits the rod, that is probably the area or most friction.

------------------
Bill Koustenis
Advanced Automotive Machine
Waldorf Md

1971 Heavy Chevy - original owner
Team Chevelle #100

I was hoping you would find this post Bill.
These are 3/8 bolts.
I sort of decided on 50 lb ft and use the moly. The last time I put this motor together, I used arps also with motor oil and 45 ft lbs. It saw over 7000 rpm several times ( not deliberatly )and stayed together, so I guess I am splitting hairs here. Just wanted a confirmation from others for that warm fuzzy feeling you get when you know it is OK.

Thanks all for the discussion and info.

Dave

Mmmmm. Warm and Fuzzy! http://www.chevelles.com/forum/biggrin.gif

<BLOCKQUOTE>quote:</font><HR>Originally posted by airrj:
Mmmmm. Warm and Fuzzy! http://www.chevelles.com/forum/biggrin.gif<HR></BLOCKQUOTE>

Guess I could have described that differently. http://www.chevelles.com/forum/smile.gif

Called the engine builder. DOH!
He says they run the 3/8 arp rod bolts to 55 ft lbs with 30 wht oil and forget it. http://www.chevelles.com/forum/rolleyes.gif
Whoda thunk it?




[This message has been edited by SS_Dave (edited 02-20-2003).]

I got this email from Chris B. ar ARP concerning this post. It is very interesting so I am reposting it here with his permission for all to read.


Hi Dave,

Chris Brown from ARP here. I was forwarded your e-mail discussion by a
friend who looks at the Team Chevelle website every now and then.
What you have been experiencing is the frustration of the age old battle
Of torque and friction versus load. The reason for all the different
results from different lubes and torque values, is due to the amount of
friction present between the surfaces that are scuffing against one another.
The most important factor to monitor is the stretch, because the bolts work
like a spring. To generate load, you must extend, or stretch the spring.
The amount you stretch the bolt is determined by the length, diameter
and the strength, but let's not get into that now. We at ARP calculate
the stretch for each bolt design, based on 75% of its yield strength,
the yield being the point at which the bolt has reached it's peak load
and then "feels funny".Torque is simply a twisting force, index number,
it does not equal load. The amount the rod bolt (in this case) stretches,
is determined by how much friction you have to overcome. With engine oil,
there is more friction generated than with ARP Moly Lube. This because the
friction coefficient or index if you like, for oil, is more than that of
the moly lube. In other words it is slicker. Therefore, it will take less
torque typically with moly lube, than with oil, to achieve the same amount
of stretch in the bolt. As RJ in the discussion group says, "It seems like
there is extra drag on the nut." It is very hard to predict how much
friction there will be, between the surfaces, even when you have control
over the lubricant, because of the surface finish on the spot face of the
cap and the nut bearing surface.Therefore, it is hard to predict how much
the bolt will stretch, based on the torque value being applied. When using
the stretch gauge, none of these variables come into play Because you are
not relying on a certain friction value to give you the result you need.
You simply zero the stretch gauge on the particular bolt you are going
to install and tighten the nut until you reach the correct amount of stretch,
and therefore clamp load or preload and stop. You can, on a 3/8rod bolt,
use a long series box end wrench, put it on the nut, install the stretch
gauge over the top and watch the stretch gauge as you tighten the nut.
Several of the tool companies out there have extra long box end wrenches
for certain jobs and with more leverage, it is certainly easier.

Best regards,

Chris Brown.


I had already found this out Friday night and Saturday morning, but it was nice to hear from Chris at ARP to confirm what Crash and I had discovered. My bolts are stretched to .0055 - .006. This took up to 94 lb ft on one bolt and as little as 55 on some others. Most took around 75 - 85 ft lbs. The ARP bolts I used were from Summit. Part number 135-6002.

Hope this helps.

Dave