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Arp L19 3/8 Conrod Bolt Torque Specs?

GTRNUR

By GTRNUR,
in Engines & Forced Induction

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GTRNUR Grand Master

GTRNUR

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Ive googled till I can google no more and just cant seem to find torque specs for the 3/8th L19 conrod bolts.

Actually ive found them in quite a few places, but all the suggested torque settings have been diferent ranging from 43ft-lb to 65ftlb? Bolt stretch seems to be 0.006, but I'd like to know the correct torque setting to be sure.

Cheers,

Ian

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The Dan Grand Master

The Dan

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If you have a stretch gauge and you are getting 0.006 then it doesn't matter what the torque is. That is the most perfect way to gauge correct torque on a bolt or stud.

Secondly, you can visit the ARP website and the torque specs are in their catalogue. You did try ARP yes?

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GTRNUR Grand Master

GTRNUR

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If you have a stretch gauge and you are getting 0.006 then it doesn't matter what the torque is. That is the most perfect way to gauge correct torque on a bolt or stud.

Secondly, you can visit the ARP website and the torque specs are in their catalogue. You did try ARP yes?

I dont have access to a bolt stretch gauge just yet, but will when the engine is assembled. Its just for the machine shop so they can measure up the rod journel size with a set of bearings in it, so I can get my crank sized for the correct clearances. The machien shop doesnt have a stretch gauge either...

And yes i did look on the ARP site, and so many of their catalogues ive lost track. They mention all their torque specs for all their standard replacement bolts, but not for the after market h-beam rods that use the common 1.6" 3/8th bolts.

Edited by GTRNUR
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The Dan Grand Master

The Dan

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I dont have access to a bolt stretch gauge just yet, but will when the engine is assembled. Its just for the machine shop so they can measure up the rod journel size with a set of bearings in it, so I can get my crank sized for the correct clearances. The machien shop doesnt have a stretch gauge either...

And yes i did look on the ARP site, and so many of their catalogues ive lost track. They mention all their torque specs for all their standard replacement bolts, but not for the after market h-beam rods that use the common 1.6" 3/8th bolts.

If you can tell me the rod brand I can probably tell you the torque for them.

Alternatively, tell me the thread pitch (16 or 24 TPI) and I can also tell you what it is.

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GTRNUR Grand Master

GTRNUR

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If you can tell me the rod brand I can probably tell you the torque for them.

Alternatively, tell me the thread pitch (16 or 24 TPI) and I can also tell you what it is.

They are an eagle rod, in the hands of the machinists now. I'll probably just have them torque to 50 for machining. I know the arp2000's are definatly 43 so the L19's should do 50 safely. I guess when I do final assembly i'll be tightening a few lb at a time measuring while measuring bolt stretch...

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The Dan Grand Master

The Dan

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For the Eagle rod you will need to do them to 45ft/lbs

43 is the old torque specs for the eagle rods, Eagle revised their specs about a year ago. If you are getting the bigend tunnel re-sized (which you should do for any rod) as long as you torque them to the same as when they were re-sized, then you won't have any issues (as long as it was close - 43 vs 45 is f**k all)

But yeah, 45ft/lbs is what ARP and Eagle recommend for that.

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GTRNUR Grand Master

GTRNUR

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Strange that its the same for an L19 and ARP2000 bolt?

The last carillo WMC5 bolts I used were 5/16th and rated to 46ft-lb with a 6 thou stretch. That same stretch was at 28ft-lb with an ARP2000 bolt and 18 with a ARP8740 bolt.

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The Dan Grand Master

The Dan

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Strange that its the same for an L19 and ARP2000 bolt?

The last carillo WMC5 bolts I used were 5/16th and rated to 46ft-lb with a 6 thou stretch. That same stretch was at 28ft-lb with an ARP2000 bolt and 18 with a ARP8740 bolt.

Why is it strange?

ARP define the torque for their bolts and studs. That's why I asked the TPI as it will be easily identifiable from that. And furthermore, you should have received instructions with the torque specs that came with the rods. All eagle rods come with these.

Look at the catalogue for L19, if you can't find it then go to the standard settings for ARP 220,000psi bolt 3/8th and whatever pitch it is, if you're not happy with that then read the instructions that came with the rods, if you don't have the instructions and don't have a listed torque, then use a stretch gauge.

That is all

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GTRNUR Grand Master

GTRNUR

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The rods im using arent an RB26 rod. Im using honda size conrods and the supplier broke up one set of 4 to give me another two for my project. As a result they werent sent in the factory packaging, so no torque specs.

My above example with the 5/16th arp bolts all used the same thread pitch, and were in a h-beam 4340 forging. I used the bolt stretch method with carillo wmc5 bolts and still have the records from the assembly. At the recommended torque for an ARP2000 bolt the wmc5 bolt wasnt even at 1/2 the recommended stretch. 6-7 thou is recommended for the wmc5 bolt.

30ft-lb - 3 thou

35ft-lb - 4 thou

40ft-lb - 4.5 thou

43ft-lb - 5 thou

45ft-lb - 5.1 thou

46ft-lb - 7 thou

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The Dan Grand Master

The Dan

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It seems as though you already have the answer to your question.

If you are doing a project such as this, then you can only go off stretch to apply the correct torque. So you are going to have to get a stretch gauge to determine the correct torque.

All of this information would have been helpful at the start.

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GTRNUR Grand Master

GTRNUR

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Not really... the 5/16th bolts were in a vw engine and are 1.5" long... not 3/8th and not 1.6.

I only borrow the stretch gauge when I am doing final assembly normally, and use the recommended torque specs only for pre-assembly checks and to give the machine shop. Im not a professional engine builder by any means. I need to buy a gauge but just havent gotten around to it yet and they arent exactly an off the shelf item in Cairns. I only know of one other builder up here that uses one, not that I talk to all the builders up here either.

Edited by GTRNUR
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The Dan Grand Master

The Dan

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Not really... the 5/16th bolts were in a vw engine and are 1.5" long... not 3/8th and not 1.6.

I only borrow the stretch gauge when I am doing final assembly normally, and use the recommended torque specs only for pre-assembly checks and to give the machine shop. Im not a professional engine builder by any means. I need to buy a gauge but just havent gotten around to it yet and they arent exactly an off the shelf item in Cairns. I only know of one other builder up here that uses one, not that I talk to all the builders up here either.

Yeah I know what you are saying but I am telling you that there is not going to be a torque spec for those bolts in that application. Different rod material and different conrod bolt = different torque. You can go off the torque for the bolt diameter and pitch, it may be close or it may be exact. You need to use a stretch gauge, you have no choice.

http://www.rocketind.com.au/descriptions.p...rtno=AR100-9941

order it now and you'll see it before the end of the week.

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