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Thread: Must you resize connecting rods?

  1. #1
    Junior Member SHOW GUEST
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    Nov 2007
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    Must you resize connecting rods?

    I have had many sets of rods redone at local machine shop and was told big end must be machined every time you change rod bolts and nuts. Is this the case with relacement ARP bolts all the time? It is getting a bit costly. What would happen if bolts were changed and rod big end was left alone? Rods are Ford 302, 351w, and FE big block rods. Thanks.

  2. #2
    Senior Member DYNO OPERATOR
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    first change rod bolts and bolt rods together tight (torqued) see if there is a edge or lip between the rods halves (bearings out) Another way to say this is do the rods mate perfect between the two halves?? THEY NEED TO!!! Also done have a ton of runs on them and expect them to not need rebuilding!!!! I done this and ben fine when in doubt rebuild em!!!!!!!!!!!! David.

  3. #3
    Junior Member SHOW GUEST
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    Maybe OK...........

    Thanks for the reply David. When I changed all bolts and nuts on one set of rods, I took and measured the inside dia, and it was constant at various points inside the big end. Would that be a proper indication that they are OK? Thanks.

  4. #4
    Senior Member MASTER BUILDER
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    buy a bore gauge ,and measure them
    i think they wanted you to buy stuff all the time , or not get sued for telling you something wrong??
    rod / rod bolt stretch is one thing , but to resize every time you change a bolt is- ridiculous

    spend the money on a good bore gauge ,and you can use it to check a lot of stuff you will get your money out of it, AND ITS ALWAYS GOOD TO DOUBLE CHECK A SHOPS WORK!!! 8)

  5. #5
    Senior Member RACING JUNKIE
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    Quote Originally Posted by Racefab57
    first change rod bolts and bolt rods together tight (torqued) see if there is a edge or lip between the rods halves (bearings out) Another way to say this is do the rods mate perfect between the two halves?? THEY NEED TO!!! Also done have a ton of runs on them and expect them to not need rebuilding!!!! I done this and ben fine when in doubt rebuild em!!!!!!!!!!!! David.
    Like he said.

    In a stock type press in rod bolt, the bolt is the clamping force along with the locating pin.

    If the pin is changed, the location of the cap may change as well.

    In an aftermarket rod, using screw in bolts, there is a locating dowel that mates the two halves together. In these cases, the bolts are simply providing clamping force, and not locating.

    I would always resize the rods when changing bolts. But, I guess the question would be... How often are you changing bolts that you're concerned about resizing the rods?
    -WJ Birmingham

    OneBadGMC.com

  6. #6
    Senior Member MASTER BUILDER
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    Quote Originally Posted by OneBadGMC
    Quote Originally Posted by Racefab57
    first change rod bolts and bolt rods together tight (torqued) see if there is a edge or lip between the rods halves (bearings out) Another way to say this is do the rods mate perfect between the two halves?? THEY NEED TO!!! Also done have a ton of runs on them and expect them to not need rebuilding!!!! I done this and ben fine when in doubt rebuild em!!!!!!!!!!!! David.
    Like he said.

    In a stock type press in rod bolt, the bolt is the clamping force along with the locating pin.

    If the pin is changed, the location of the cap may change as well.

    In an aftermarket rod, using screw in bolts, there is a locating dowel that mates the two halves together. In these cases, the bolts are simply providing clamping force, and not locating.

    I would always resize the rods when changing bolts. But, I guess the question would be... How often are you changing bolts that you're concerned about resizing the rods?


    hey have you seen the grp aluminum rods with the grooves for alignment ?
    what happens when the rods get hot,and the cap,and arm come closer because of heat ,and torq?, this will be tighter on the crank, has anyone had any problems like that?

    will these rods last for years??
    check out video, look at 4:19
    http://www.youtube.com/watch?v=Y8lk06O1CeI


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