Move ARP rod bolt to a new rod?

[turbogrill]

Hi,

 

Can I remove the ARP rod bolts from a different rod and install in a new rod?

 

I am rebuilding a junk engine and would like to reuse the ARP rod bolts I had on a different engine. The ARP rod bolt/nuts are reusable, just curious if I destroy them by uninstall them.

 

They are installed with a press. The machine shop would to this.

 

These are the install instructions if it matters:

 

[mender]

I've reused ARP rod bolts but only when I couldn't get another set quickly enough. Given the price of a new set I go that route whenever I can, not worth the bother or risk IMHO.

 

But if you are going to re-use them, make sure they are pressed out carefully so the threads don't get damaged. That means pressing on just the centre of the rod bolt end and making sure the bolt comes through the rod without rubbing threads against the edge of the hole. If you don't have a stretch gauge and the threads get rubbed/damaged, toss them because your critical torque settings are no longer trustworthy. Also inspect the knurled part for material transfer or damage that will affect the press fit into the next set of rods.

 

It's been quite a while since I did the last set of L-series ARP rod bolts so I don't remember if they pressed hard or not. Again, generally not worth the risk to re-use them.

[turbogrill]

10 hours ago, mender said:

I've reused ARP rod bolts but only when I couldn't get another set quickly enough. Given the price of a new set I go that route whenever I can, not worth the bother or risk IMHO.

 

But if you are going to re-use them, make sure they are pressed out carefully so the threads don't get damaged. That means pressing on just the centre of the rod bolt end and making sure the bolt comes through the rod without rubbing threads against the edge of the hole. If you don't have a stretch gauge and the threads get rubbed/damaged, toss them because your critical torque settings are no longer trustworthy. Also inspect the knurled part for material transfer or damage that will affect the press fit into the next set of rods.

 

It's been quite a while since I did the last set of L-series ARP rod bolts so I don't remember if they pressed hard or not. Again, generally not worth the risk to re-use them.

Thanks!

 

I will go ahead on by a new set, costs $60.

 

What is your take on "stretch method" vs tighten to recommended torque?

 

 

[mender]

I use both methods, stretch for race engines and torque for street. I also check my torque wrench against the stretch gauge every so often just to make sure.

 

Stretch is the most accurate because the tension is what holds the rod cap on.

[turbogrill]

1 hour ago, mender said:

I use both methods, stretch for race engines and torque for street. I also check my torque wrench against the stretch gauge every so often just to make sure.

 

Stretch is the most accurate because the tension is what holds the rod cap on.

 

So what would be the downside with using the torque method. Things are two tight and potential loss of power?

[mender]

So far the worst change in cap dimension that I've found is about 0.0002-3", not usually enough to cause problems.

 

Usually the issue with torque readings is not quite enough stretch because the threads are new, not enough or wrong lube, torque wrench calibration, that result in too little preload on the rod bolt. This only becomes an issue when the max piston speed is reached and the spring action of the rod bolt preload isn't quite enough to keep the cap from moving. Bearing shell cap moves around, scrapes the oil off the journal and boom!

[turbogrill]

10 hours ago, mender said:

So far the worst change in cap dimension that I've found is about 0.0002-3", not usually enough to cause problems.

 

Usually the issue with torque readings is not quite enough stretch because the threads are new, not enough or wrong lube, torque wrench calibration, that result in too little preload on the rod bolt. This only becomes an issue when the max piston speed is reached and the spring action of the rod bolt preload isn't quite enough to keep the cap from moving. Bearing shell cap moves around, scrapes the oil off the journal and boom!

 

Got it! Thanks

 

On the L28 there seems to be all sorts of problems and challenges  when going over 7000 RPM so from a cost/work/skill perspective it makes sense to stay on stockish RPM ranges (<6500 rpm).  

 

 

 

[mender]

19 minutes ago, turbogrill said:

 

Got it! Thanks

 

On the L28 there seems to be all sorts of problems and challenges  when going over 7000 RPM so from a cost/work/skill perspective it makes sense to stay on stockish RPM ranges (<6500 rpm). 

3

I ran the 4 cylinder L series engines in my 510 way back in the '80s and didn't go much over 7000 even with them, usually under 7500 rpm.

 

We did lots of silly things back then including using Chev rod bolts because ARP didn't make L series bolts yet. So much easier now.

 

Oh, when you use new bolts, do as the instructions say and torque and untorque them three times before doing it for final to wear the threads a bit and get a clean pull.

Edited September 4, 2018 by mender