Scat arp 2000 rod bolts

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Are these the cap screw rod bolts that you’re supposed to use a stretch indicator fixture to measure them while you torque them with a boxed end torque wrench adapter? If so, it’s whatever stretch that the manufacturer torques them to before the big end of the rod is final sized. Of course, torque spec is still important. If it stretches the set amount before it has reached torque yield, then it’s a stretchy bolt that has been overstressed during use or it was defective when manufactured.
 
Garrett Ellison said:
Are these the cap screw rod bolts that you’re supposed to use a stretch indicator fixture to measure them while you torque them with a boxed end torque wrench adapter? If so, it’s whatever stretch that the manufacturer torques them to before the big end of the rod is final sized. Of course, torque spec is still important. If it stretches the set amount before it has reached torque yield, then it’s a stretchy bolt that has been overstressed during use or it was defective when manufactured.
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Thank You for putting that in Layman's Terms! I'm kinda familiar with them, but only by reading, as I've Never Used 'em... sounds like a pain. Seems like the Old MP rod bolts I just knocked in (well, not exactly) and torqued a Lil at a time. Never just run em down! Lol
 
And there’s the catch to those types of rod bolts. I remember when those came out my chebby neighbors out the road from me blew up several of their fresh engines after switching to rods that came with the direct stretch measurement rod bolts. And it was because of the mentality that “torque spec is what you go by” and “that gauge is too expensive” “that’s too much trouble to go through.” Yada, Yada, Yada… and the sad part is that there was a plague of that happening when they went to where they where buying them from. Of course the shop owners where blaming the ARP rod bolts, not the fact no one was following the directions on how they were supposed to be installed.
 
That's the Deal, Manufacturers Specifications/ Instructions Trumps All other Methods. Even seen it in Construction, Many Times! Hardy Plank cement board? The Back of the Head of the Nail MUST BE Flush with the product. It cannot over penetrate, nor be proud of the board. Or NO WARRANTY. DuraRock cement board for tile? 1/4" square notch trowel the Full Substrate side (bottom) Then screw @6" o.c. all the way around, up down, and in the field. People just wanna throw stuff up there.....
 
I don’t stretch rod bolts. I’ve seen a pretty big difference in torque to get two bolts to the same stretch.

Tom Leib (owner of Scat) said in a webinar not to stretch rod bolts.
 
Rat Bastid said:
I don’t stretch rod bolts. I’ve seen a pretty big difference in torque to get two bolts to the same stretch.

Tom Leib (owner of Scat) said in a webinar not to stretch rod bolts.
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I'll PROBABLY never get to play with the fancy stuff like that.... but I like to stay informed on the Game. I'll Never be that good, Because I didn't make a Life outta it. I made a Life outta Construction instead... suck *** life choices will screw Ya! LOL
 
I wonder if the last entry on the chart in post #17 is a misprint & should be 70, not 63.
Reasoning is: longer bolt, more thread engagement & friction, therefore more TQ needed to stretch the bolt to the reqd amount of clamping force.
 
Bewy said:
I wonder if the last entry on the chart in post #17 is a misprint & should be 70, not 63.
Reasoning is: longer bolt, more thread engagement & friction, therefore more TQ needed to stretch the bolt to the reqd amount of clamping force.
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It wouldn't hurt to call them..
 
I just opened a pack of replacement ARP bolts from Eagle. The instruction sheet is printed by Eagle and they have different torque values for the same fasteners on their instruction sheet. A few pounds more than the chart I posted from Scat on the same material and length.
 
It wouldn't hurt to call them..
Definitely so. Even if the bolt holds at improper torque the big end of may not be as round as it’s supposed to be. There are good reasons to have a dial bore gauge, rod vice, micrometer and to measure bearing bore and crank pins before assembly.
 
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o1heavy said:
This has turned into a real pain
But does anyone know the torque specs
On the arp 2000 rod bolt used with the scat rotating assembly ?? 360/408
The arp website is not very helpful

I may be over looking it ,
But tired of digging for it ,
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Stretch gauge only imho
 
When I was putting mine together I called Scat to get a stretch value for that bolt in their H beam rod. They didn’t know, just gave me the torque setting. I finally torqued one and measured the stretch. It was very repeatable and consistent all the way through. Should have called ARP. I was concerned that Scat honed the rod at a torque value, then I stretch it to an ARP spec, which could be different. Wasn’t happy, but no issues after 5 years and 100’s of passes. Could be a mountain out of a mole hill, but it’s a rod bolt!
 
furrystump said:
When I was putting mine together I called Scat to get a stretch value for that bolt in their H beam rod. They didn’t know, just gave me the torque setting. I finally torqued one and measured the stretch. It was very repeatable and consistent all the way through. Should have called ARP. I was concerned that Scat honed the rod at a torque value, then I stretch it to an ARP spec, which could be different. Wasn’t happy, but no issues after 5 years and 100’s of passes. Could be a mountain out of a mole hill, but it’s a rod bolt!
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If posted this a half dozen times, maybe more. I’ll post it again because it’s exactly what I’ve been saying.

Tom Leib who owns Scat is 100% against stretching rod bolts. At one time I posted the link to the webinar he gave where he covered it.

I quit stretching bolts a long time ago because I learned the hard way what Leib was saying.

No matter how good the bolt is, they stretch at different torque values. When you do that, you pull the hole out of round. Yes, you can size them and make them round again, but…and this is a big BUT under heat and load the big end will distort to the unequal load on the bolts.

I found this out because I was meticulously measuring, recording and stretching every rod bolt I had. And anyone else that I was building junk for. And, I saw a trend.

That trend was running steel rods the bearings may look a bit wonky SOMETIMES. But you stretch a rod bolt in an aluminum rod and the rod bearings will look like **** in short order.

Most of that stuff was 8k plus but you could see it happening plain as day. So I called Childs & Albert (I ran those rods for a bit) and Bill Miller and several other aluminum rod manufacturers and only C&A said to stop stretching the bolts.

Then I decided I better call on some people smarter than me who were building big power aluminum rod **** and every single one said stop stretching the bolts and torque them so the load at the parting line is as close as you can get.

And all the wonky looking rod bearing crap stopped. Even the steel rod stuff.

I will not stretch a rod bolt. It’s the only bolt that even possible to stretch in an engine. I suspect someone decided since they could measure it it must be done. It’s a great exercise but that’s about it for me.

If you are worried about rod bolt failure, measure then when they are new and measure them every time you do updates and see what you get.
 
Thanks! I appreciate it! I thought it was odd for Scat not to have the spec. Makes sense now.
 
Rat Bastid said:
If posted this a half dozen times, maybe more. I’ll post it again because it’s exactly what I’ve been saying.

Tom Leib who owns Scat is 100% against stretching rod bolts. At one time I posted the link to the webinar he gave where he covered it.

I quit stretching bolts a long time ago because I learned the hard way what Leib was saying.

No matter how good the bolt is, they stretch at different torque values. When you do that, you pull the hole out of round. Yes, you can size them and make them round again, but…and this is a big BUT under heat and load the big end will distort to the unequal load on the bolts.

I found this out because I was meticulously measuring, recording and stretching every rod bolt I had. And anyone else that I was building junk for. And, I saw a trend.

That trend was running steel rods the bearings may look a bit wonky SOMETIMES. But you stretch a rod bolt in an aluminum rod and the rod bearings will look like **** in short order.

Most of that stuff was 8k plus but you could see it happening plain as day. So I called Childs & Albert (I ran those rods for a bit) and Bill Miller and several other aluminum rod manufacturers and only C&A said to stop stretching the bolts.

Then I decided I better call on some people smarter than me who were building big power aluminum rod **** and every single one said stop stretching the bolts and torque them so the load at the parting line is as close as you can get.

And all the wonky looking rod bearing crap stopped. Even the steel rod stuff.

I will not stretch a rod bolt. It’s the only bolt that even possible to stretch in an engine. I suspect someone decided since they could measure it it must be done. It’s a great exercise but that’s about it for me.

If you are worried about rod bolt failure, measure then when they are new and measure them every time you do updates and see what you get.
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Using a torque wrench still stretches the bolts
So this makes no sense to me. Stretch is a measure of torque and vice versa.
 
Duane said:
Using a torque wrench still stretches the bolts
So this makes no sense to me. Stretch is a measure of torque and vice versa.
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I get that. Have you ever stretched a set of bolts and then measured the torque required to get the same stretch? It can be quite a difference. I can’t remember how much difference I saw but the rod bearings weren’t happy.

The uneven torque changes the load across the parting line.

I will see if I can find the webinar where Leib talked about stretching rod bolts.
 
Rat Bastid said:
I get that. Have you ever stretched a set of bolts and then measured the torque required to get the same stretch? It can be quite a difference. I can’t remember how much difference I saw but the rod bearings weren’t happy.

The uneven torque changes the load across the parting line.

I will see if I can find the webinar where Leib talked about stretching rod bolts.
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Yes that is why rod bolts should be stretched with a rod bolt gauge. Torque has too many variables.
 
Rat Bastid said:
I get that. Have you ever stretched a set of bolts and then measured the torque required to get the same stretch? It can be quite a difference. I can’t remember how much difference I saw but the rod bearings weren’t happy.

The uneven torque changes the load across the parting line.

I will see if I can find the webinar where Leib talked about stretching rod bolts.
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What do you mean by uneven load ?
 
Duane said:
What do you mean by uneven load ?
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Did you watch the video I posted?

Stretch your bolts if you want to. I say it’s bullshit. It’s an exercise in futility. I do know my rod bearings don’t look like crap any more.
 
Rat Bastid said:
Did you watch the video I posted?

Stretch your bolts if you want to. I say it’s bullshit. It’s an exercise in futility. I do know my rod bearings don’t look like crap any more.
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Well I watch the harmonic dampener video.
No mention of rod bolts there.
I don’t thing a stretch gauge is bull. Torque can work, but I think you need the gauge to give you a reference setting. You need to know how much torque is giving how much stretch. But I am curious to here this stretch video if you can find it.
 
Duane said:
Well I watch the harmonic dampener video.
No mention of rod bolts there.
I don’t thing a stretch gauge is bull. Torque can work, but I think you need the gauge to give you a reference setting. You need to know how much torque is giving how much stretch. But I am curious to here this stretch video if you can find it.
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Damn. Then I have to go find another webinar he did where he talked about rod bolts. I can’t do that right now, but I will later today. So I will find it. Even if I have to call Scat and have Tom give me the date.

Let me say this another way. I’m saying stretch isn’t important. It’s the load across the parting line that matters, and that load is by torquing the bolt.

The stretch numbers can change the torque. The rod hole “sees” that. You have unequal load on both bolts, but the bolts are the same length.

You can see this in rod bearings, especially at high RPM. Doesn’t matter how good the rod is. The rod pulls apart at the parting line. Back in the day rods used to be resized out of round so they went round under load.

Fortunately today we have bearings that are thinner at the parting line so we don’t have to do that.

But the rod still tries to close up at the parting line. When the bolts are stretched and the torque isn’t the same, the load across the parting line isn’t equal. When that happens, the hole goes out of round unequally.

That’s why I stopped stretching rod bolts. I’d rather have to add 5 or 10 pounds of torque on the bolts if I think I need it and keep both bolts at that same torque then to stretch the bolts and end up with two different torque loads on the bolts and cap.
 
I have never used the stretch to decide how torqued it should be. I was always to the understanding that the stretch was checked to make sure the bolt was not failing. hence why it says " Not to Exceed " and doesnt give a range of acceptable stretch.
 
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