Rod torque question

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Nov 14, 2010 | 10:08 AM

6.055chevy

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Staging Lane

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Rod torque question

Hello guys, I have a dumb question. When torquing the rods in a ls2 new design with floating rods. When it says torque 15 lbs then 75 degrees that means 75 of 360 right? So a little less than a 1/4 turn more.

Does Gm say to replace the bolts? Can I use the old one's again? I had to change crank as the thrust went out.

Thanks

Nov 14, 2010 | 10:20 AM

Darkman

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From: Spring, Texas

Yes specification in degrees relates to a 360 circle. GM has revised that specification from 75 degrees to 85 degrees.

The bolts should not be reused (per GM Technical Service Bulletin that revised the torque specification).

Nov 14, 2010 | 10:44 AM

6.055chevy

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Thank you Darkman

I thought this as I have been told with torque to yield bolts not to use them again.

I will order some ARP.

Thanks again.

Nov 14, 2010 | 11:35 AM

KCS

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From: Conroe, TX

Quote:

Originally Posted by Darkman

I could have sworn I read that you can reuse the rod bolts. It would make sense too considering that the old 75 degree spec shouldn't put the bolt into yield when the new revised spec is 85 degrees.

In fact, here is an article a buddy sent me regarding the rod bolts.

http://www.enginebuildermag.com/Arti...rod_bolts.aspx

Nov 14, 2010 | 01:33 PM

Darkman

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Quote:

Originally Posted by KCS

I did not mean to suggest that the bolts postively could not be reused - the original question went to what GM says - which is what I reported.

Having said that, I personally cannot bring myself to reuse bolts or gaskets that live inside the motor - but that is paranoia as opposed to protocol.

Nov 14, 2010 | 03:05 PM

KCS

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Sorry, I wasn't saying you were right or wrong, just opening up a discussion with an opposing point of view.

I'm personally ok with reusing some TTY bolts in most instances. If the TSB says that the new torque angle is 85 degrees, the old spec of 75 degrees should be safe so as not to put the fastener into yield, or plastic deformation for that matter, so the fastener should be ok to stretch again.

Nothing wrong with swapping them out for ARP's though...that is unless the big end isn't resized. But that's another argument all together, lol.

Nov 14, 2010 | 03:27 PM

6.055chevy

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Nothing wrong with swapping them out for ARP's though...that is unless the big end isn't resized. But that's another argument all together, lol.[/QUOTE]

I ordered some arp bolts. I don't see why you would have to resize the rods as they are not like the old rods where the bolts lined the cap up and where pressed in changing the shape of the cap. The crack cap uses the crack to line the two halfs. I only pulled the crank from the engine and did not take the heads off. So I'm just going to change the bolts and put it back together. If she blows I'll just buy a take out motor and start over.

Thanks guy for your help

Darrin

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Nov 14, 2010 | 04:06 PM

KCS

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From: Conroe, TX

Quote:

Originally Posted by 6.055chevy

I ordered some arp bolts. I don't see why you would have to resize the rods as they are not like the old rods where the bolts lined the cap up and where pressed in changing the shape of the cap. The crack cap uses the crack to line the two halfs. I only pulled the crank from the engine and did not take the heads off. So I'm just going to change the bolts and put it back together. If she blows I'll just buy a take out motor and start over.

Thanks guy for your help

Darrin

It's the increased clamp load from the ARP's that distort the housing bore and that will have a direct effect on the bearing. Some people swap them out and have no issues, some people blow their engine up. It's hit or miss, but IMO it's not worth the risk.