Re: Rod bolt stretch questions
[Re: Wirenut]
#2762048
04/09/20 08:29 PM
04/09/20 08:29 PM
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Joined: Feb 2005
Posts: 20,201 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,201
PA.
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Wow!!! So you are at 100 foot pounds.
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: Rod bolt stretch questions
[Re: pittsburghracer]
#2762063
04/09/20 08:47 PM
04/09/20 08:47 PM
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Joined: May 2016
Posts: 630 Ct
Wirenut
OP
mopar
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OP
mopar
Joined: May 2016
Posts: 630
Ct
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Wow!!! So you are at 100 foot pounds. LOL cmon man, who wants to see that response!!!!!!!!! Omg that made me laugh! Yeah but maybe my t wrench is off by 20llbs.? That’s why I’m asking , Don’t know what I should be expecting G
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Re: Rod bolt stretch questions
[Re: Wirenut]
#2762079
04/09/20 09:10 PM
04/09/20 09:10 PM
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Joined: Aug 2003
Posts: 43,303 Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,303
Bend,OR USA
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The torque needed to reach the desire length can and will vary with ARP bolts, especially if they are custom made ARP 2000 for one of the high end rod makers like Molnar I've seen those bolts over stretch at 53 Ft. Lbs. on one bolt and seen others in the same batch of rods take 83 Ft. lbs. to get in the middle of from .0057 to .0062 bolt stretch Which ARP bolts are you going to use? Do one at a time and record the torque needed to get the stretch where you want it and keep it for later on if your planning on looking at the rod bearings so you can retorque them back to exactly what they needed to stretch properly. Do not use the torque plus so many more degrees of rotation to tighten them
Last edited by Cab_Burge; 04/09/20 09:38 PM.
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Rod bolt stretch questions
[Re: Wirenut]
#2762089
04/09/20 09:27 PM
04/09/20 09:27 PM
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Joined: Aug 2011
Posts: 2,872 Pattison Texas
CSK
master
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master
Joined: Aug 2011
Posts: 2,872
Pattison Texas
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Hi guys, Decided to replace my rod bolts , eagle rods , 8740 arp. , unknown history. Decided to try the stretch method as it makes sense to me. Previously only used torque spec. I realize my torque wrench is old so felt the stretch method could discount poor wrench calibration. I am using the method of stretching the bolts with rod in a rod vice and recording torque required to do so . I am following the arp guide lines and using their supplied lube. I have read through all of the threads here I could find so I could best understand the process and methods. I have done one rod and was able to achieve the recommended stretch.
My concern . In order to achieve the recommended stretch I am 37 ftlbs over the speced 63 ftlbs. I am going to try a different torque wrench tomorrow to see if the value differs.
Is what I’m finding typical for an amateur with average tools?
Thanks for looking G So are you going to have the big end checked after the new rod bolts & different way of tightening the bolts thus changing the amount of clamping force ?
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: Rod bolt stretch questions
[Re: Cab_Burge]
#2762090
04/09/20 09:28 PM
04/09/20 09:28 PM
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Joined: May 2016
Posts: 630 Ct
Wirenut
OP
mopar
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OP
mopar
Joined: May 2016
Posts: 630
Ct
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The torque needed to reach the desire length can and will vary with ARP bolts, especially if they are custom made ARP 2000 for one of the high end rod makers like Molnar I've seen those bolts over stretch at 53 Ft. Lbs. on one bolt and seen others in the same batch of rods take 83 Ft. lbs. to get in the middle of from .0057 to .0062 stretch. Which ARP bolts are you going to use? Do one at a time and record the torque needed to get the stretch where you want it and keep it fo rlater on if your planning on looking at the rad bearings so you can retorque them back to exactly what they needed to stretch properly. Do not use the torque plus so many more degrees of rotation to tighten them Thanks for responding mr cab . They are 8740 arp
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Re: Rod bolt stretch questions
[Re: jwb123]
#2762103
04/09/20 10:14 PM
04/09/20 10:14 PM
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Joined: May 2016
Posts: 630 Ct
Wirenut
OP
mopar
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OP
mopar
Joined: May 2016
Posts: 630
Ct
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I build a few engines, I am not a high end engine builder. I do use a rod stretch gauge when the rod has the proper bolts. My experience is that it usually takes 5 to 10 lbs more torque to stretch the bolt to specs given. I have never seen something like you describe. I build about 7 to 10 engines a year. Hmm thanks G
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Re: Rod bolt stretch questions
[Re: dvw]
#2762152
04/10/20 05:35 AM
04/10/20 05:35 AM
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Joined: May 2016
Posts: 630 Ct
Wirenut
OP
mopar
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OP
mopar
Joined: May 2016
Posts: 630
Ct
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My experience with using stretch is the torque readings vary greatly. The last time I used torque angle specs provided by Tom Molnar. The stretch numbers were very close. The torque numbers were recorded using a Snap-on electronic wrench. The numbers were much closer together. Sneaking up on stretch creates a lot of friction skewing torque readings. As stated if you don't have a good method to measure each bolt at the start and finish and keep exact records the entire process is useless. Doug Ok thanks all. I am going to trash these bolts get two more and just torque them to spec. With a known accurate wrench G
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Re: Rod bolt stretch questions
[Re: Wirenut]
#2762207
04/10/20 10:02 AM
04/10/20 10:02 AM
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Joined: Jan 2012
Posts: 2,678 Stuttgart, Arkansas
rickseeman
master
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master
Joined: Jan 2012
Posts: 2,678
Stuttgart, Arkansas
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My results are similar to yours. ARP makes real hard bolts. And trying to get them to stretch takes way more torque than I want to put on a little rod. Why does everything have to be so complicated? Sometimes I just torque them to the recommended torque realizing that I surely didn't get them to the stretch that it calls for. Bear in mind that everything is going to be fine and it's not going to come apart because you didn't get the proper stretch.
2011 Drag Pak Challenger
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Re: Rod bolt stretch questions
[Re: BigBlockGTS]
#2762234
04/10/20 10:49 AM
04/10/20 10:49 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Look at the brand name and call that company.. a lot of places have equipment to cal them... I use to get it done at work then from Snap On.. check the tool trucks for there service
Last edited by MR_P_BODY; 04/10/20 10:51 AM.
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