measuring rod bolt stretch & preload

Discussion in 'Tools, Procedures, and Testing trouble shooting' started by grumpyvette, Mar 1, 2015.

  1. grumpyvette

    grumpyvette Administrator Staff Member

    http://arp-bolts.mobi/p/tech.php?page=3

    http://arp-bolts.mobi/p/tech.php?page=2

    http://www.hotrod.com/how-to/engine/116 ... etch-tool/

    http://arp-bolts.com/

    http://www.harborfreight.com/1-inch-tra ... r-623.html

    http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/#post-44530

    read the factory shop manual or connecting rod manufacturers info VERY carefully...FT LBS AND NM ARE NOT THE SAME
    http://www.kylesconverter.com/torque/newton-meters-to-foot--pounds-force

    IF you do some careful shopping you'll find that decent connecting rods are available at semi reasonable prices, I would insist on 7/16" ARP rod bolts and 4340 forged steel, and suggest SCAT, as a lower cost but good value connecting rod source








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    you'll
    need accurate precision measuring tools

    http://garage.grumpysperformance.com/index.php?threads/precision-measuring-tools.1390/
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    http://www.amazon.com/T%C3%BCrlen-Indic ... +indicator
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    BTW IF YOUR SEMI SKILLED AT FABRICATION, AND HAVE THE SKILL AND PATIENCE,
    a $3 C clamp and a $15-$45 dial indicator some set screws and some time on a drill press and a few taps ETC.,( AFTER THINKING IT THRU CAREFULLY OF COURSE) can make you a fully functional rod bolt stretch gauge for peanuts, rather than spending the $60-to-$260 a factory produced stretch gauge commonly costs

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    AS AN EXAMPLE
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    http://www.slidewright.com/kuu-3-way-cl ... 7Aodkh0Amg
    http://www.summitracing.com/parts/arp-1 ... /overview/ $248
    http://www.summitracing.com/parts/arp-1 ... /overview/ $186
    yes you can find non-name brand rod bolt stretch gauges from about $50-$80

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    http://www.jegs.com/i/JEGS-Performance- ... Id=1130494
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    ARP rod bolts are set up to use a stretch gauge with both ends of the bolt pre-machined for the gauge the bolt packaging from ARP,comes with the correct length the bolts are supposed to reach under the correct pre-load tension, in the instructions OR its available on their web site
    youll need a good quality torque wrench
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    and a torque angle gauge

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    most guys are familiar with use of a torque wrench to tighten rod bolts to the correct preload, but while this gets you very close its not as precise as a rod bolt stretch gauge,
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    Last edited by a moderator: Nov 26, 2018
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    ITS mandatory that YOU as an engine builder be aware that theres a few machine shops that are run by scam artists willing , even happy to cheat the less informed customers, and the decepion and cost cutting saves them considerable money while basically providing you with a very inferior product at an inflated price.
    IMPORTED parts from over seas being substituted for much more expensive, well known brand name components, DOES HAPPEN!
    It helps your engine's potential durability tremendously, if you take the time and effort to verify that you have, and that if you have a machine shop do all or part of your engine assembly that they, actually had the quality components, you paid for installed in your engine, Ive had several machine shops try to pass off and install really crappy quality components in engines while charging top dollar for brand name parts.
    now I'm sure that easily 70% -90% of the guys never bother to check what they got back from the machine shop for accurate machine work or that simple things like the bolts, studs and bearings , rings and gaskets the machine shop used during the engine assembly were actually the parts you paid for, but I know for a fact that less than honest shops don,t bat an eye over making a few bucks extra with this bait and switch B,S.
    Ive seen connecting rods, main caps, studs rockers push rods pistons, piston rings, cranks and several other components being billed as name brand components and lesser quality parts actually installed!
    there was a machine shop in Hollywood florida , that for decades was well known for this deceptive practice

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    example
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    RULE#1 if your not sure about some aspect of engine assembly or clearancing,

    STOP!.. do your research, ask questions and get info from a couple reliable sources before proceeding further
    check your factory shop manual for torque specs or contact the connecting rod manufacturer,


    https://racetoolsdirect.com/product...MI-cu3zOzv3gIVi4nICh1iVgDKEAQYASABEgJ2AvD_BwE
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    https://www.amazon.com/JEGS-80591-B...159417&sr=8-3&keywords=rod+bolt+stretch+gauge

    (my choice in a rod bolt stretch gauge)
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    https://www.summitracing.com/parts/pow-pow101300/overview/
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    http://www.eaglerod.com/mosmodule/bolt_torque.html

    What Do I Torque the Bolts To?
    The first step is to identify which bolts you have. Eagle rods are offered with a variety of different bolts. Each of which has a different torque requirement. Proper bolt torque is paramount to rod strength and life. Eagle does not use "off the shelf" ARP bolts. Eagle has ARP custom make bolts to our specifications. DO NOT use torque specs for off-the-shelf ARP bolts. Here is a diagram of some important bolt identifying features.
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    The following chart shows the head of the bolt, the dimensions, and the proper torque spec. Be careful! the heads of some bolts look similar and some even have the same markings. DO NOT identify the bolt by the head alone. Verify dimensions also! If the head of your bolts do not match one of the pictures below - you do not have Eagle rods! Please consult the manufacturer of your rods for proper torque specs. Their torque spec is most likely different than ours! Always use ARP moly lube on the threads and under the head of the bolt when torquing!
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    8740
    7/16"
    1.500"
    3/8"
    40 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    8740
    7/16"
    1.600"
    7/16"
    63 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    8740
    7/16"
    1.750"
    7/16"
    63 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    8740
    7/16"
    1.800"
    7/16"
    63 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    2000
    3/8"
    1.500"
    5/16"
    28 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    2000
    7/16"
    1.500"
    3/8"
    43 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    2000
    7/16"
    1.600"
    7/16"
    75 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    2000
    7/16"
    1.800"
    7/16"
    75 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    L-19
    1/2"
    1.600"
    7/16"
    79 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    L-19
    1/2"
    1.750"
    7/16"
    79 ftlbs
    [​IMG]
    material
    socket
    size
    under
    head
    length
    thread
    size
    torque
    CA 625+
    3/8"
    1.500"
    5/16"
    32 ftlbs
     
    Last edited: Nov 25, 2018
  3. 87vette81big

    87vette81big Guest

    Holy Crap Grumpy.
    China Imitation ARP Rod Bolts.

    How Low can you Get ?
     
  4. 87vette81big

    87vette81big Guest

    I have been holding off buying a Premium Rod Bolt Stretch Guage.
    Need for My Pontiac V8 Crower Race Connecting Rods of mine.
    Guys on Y.B. Racing forum recommends only JEGS OR ARP PREMIUM PRO ROD BOLT STRETCH GUAGES.

    I Like the Homemade Rod Bolt stretch guage made from a C-clamp.
    Nifty Idea.
     
  5. GLHS60

    GLHS60 Well-Known Member

    I agree rod bolt stretch is extremely important but have only measured with a micrometer.

    Not the most convenient method, but still workable.

    Thanks
    Randy
     
  6. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    I bought a Crower Rod Bolt Stretch Gauge back Winter of 2017 Grumpy.
    It was not inexpensive.
     
  7. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    [​IMG]

    My Crower connecting rod bolt stretch gauge looks like this Dyers.
    But I did not get a Starrtet Dial indicator with it !
    Ultra Nice.
     
  8. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

  9. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    torque wrench vs rod bolt stretch gauge accuracy
    I post these links hoping that most of the linked info is read and the related info is used or at least considered by the few guys who wish to become rather skilled and knowledgeable, in engine assembly.
    no one has mastered all the skills and going back over even rather common assembly skills and looking for tips on how to improve existing procedures seldom hurts.
    as time progresses, theres always on-going documented testing, and in many cases the old established way of doing things has proven to be less than ideal as newer and more detailed testing proves.
    I well remember the advice in the later 1960s to keep end gaps on upper piston rings in the .004-.005 per inch of bore diameter, and secondary compression rings , to a tighter .04 max per inch of bore diam, as they experience less heat related expansion, the gaps could be tighter, well testing over the last 40-50 years has proven that approach to be less than idea, a looser .005-.006 second compression ring end gap is now been rather conclusively proven to work a bit better as it tends to lower and trapped combustion pressure, that could reduce the top rings bore seal.
    [​IMG]
    https://www.enginelabs.com/engine-t...easuring-rod-bolt-stretch-vs-torque-with-arp/

    http://www.performanceenginetech.com/connecting-rod-bolts-stretch-vs-torque/

    https://www.hotrod.com/articles/using-rod-bolt-stretch-tool/

    http://www.superchevy.com/how-to/engines-drivetrain/49258-rod-bolt-torquing-stretch-info/


    https://ecatalog.mitutoyo.com/Spindle-Attachment-Tip-C1129.aspx

     
    Last edited: Dec 10, 2018 at 12:10 PM

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